My 2005 LLY is doing the same exact thing. My hoses look a little suspect but I didn’t think they were bad enough to cause this. I will be doing what you did today in hopes it will work. Thank you for the video. Top shelf! Will report back😢
Having the same issue with my 05 lly as well I’ve already replaced 3 of the 5 rubber hoses and it was fixed for a few days but now it’s happening again. I’ll let y’all know if it fixes it bc I’m living through the frustration of having a downed work truck
Finally!!! I'm having the exact same issue on my 04. I had s feeling it was might be a hose, but i haven't ben able to find it. I'm foing to check that hose.
My problem was the steel line coming out of the aluminum filter head. It was loose and allowing air to suck in instead of fuel. I removed the line by twisting and pulling. Cleaned it and JB welded it back in. Problem solved.
Great video, have the exact same problem on my 06 LBZ. Figured it was a tiny air leak, but I hadn't no idea what I'm looking at with that mess of wiring and lines. This helped a ton for where I should be looking and for what. I figured it would be a bigger leak than that. I probably wouldn't of even took a 2nd look at that hose.
This is the video I’ve been looking for! Thank you for the explanation at the end. My truck has been unable to smog for a month now due to P0101! I’ve already cleaned my filter and EGR, but noticed a second code now related to fuel pressure (p1093). From what I’m reading, this could be caused by a leak similar to this. Wish my luck on hunting it down. Thanks again.
Hey my 07 duramax, 2500hd. Found the suction line on drivers side 3/8” metal tube rubbed through rubbing against something 2 ft down from QD, GM flaw, many things rub and where on this model, even top radiator hoses and even the large wire QD hitting the cooler tube.
My truck has the cat fuel filter on it. Never had this issue till the last time I spun a filter on now only if the truck is facing down hill it gets air locked
My 2003 is not holding prime at all it won't start or run unless it is ether, and after hand priming it 10 minutes later, no fuel pressure. Could this be the same issue?
Mine is dry through out the truck, primer goes soft right away. Starts right up with starting fluid, and runs just fine. Could I have a leaking fuel injectors?
the issue is the primer pump assembly itself is the issue. The air leak is coming from the pimer pump oring seal on the pump allowing air to enter into the fuel line which causes the air into the fuel rail to the injector. The primer pump needs to be replaced or rebuild the primer pump. The hose clamp you used is toooooo large for the hose needs clamping which will cause leaks. NEVER use BRAKE CLEANER on ANY rubber parts which causes the rubber to become hard and brittle..
1:56 if you can already see fuel around your brass screw that should be plastic, thats a leak. the plastic will self seal when tight. brass wont. anyway if this has a leak, you lose prime also
Same exact issue with my 04.5 lly. I got a fass on it that sounds like shit so I’m wondering if that’s what it is. But it’s got a fuel pressure gauge and it shows 0 until I prime it up before starting
If you ran a smoke machine through the fuel line near the tank, do you think that smoke would have come out of that leak? I'm having a similar problem but after replacing the CP3, the FRPS, the fuel filter housing, and the hoses coming off the fuel filter housing I still get VERY low ACT fuel rail pressure on crank. Like 7 of 38 desired (on live data) no codes and if I give her a little ether bump, she will start and run perfectly. Shut her off and attempt to restart her and she will only crank no start.
I was thinking about this too. I think if you blew the lines out so theres no fuel pockets blocking the smoke it would work. You can also disconnect the lines at the tank and lightly pressurize the system and check with soapy water. Last option would be to see if anyone makes a UV dye for fuel that wont hurt anything... like leak checking an AC system. These systems are tricky. The smallest little leak wreaks havoc, as you are experiencing.
This is the exact same issue I am having except if I push the primer when the truck starts to die it will keep running, did you try to do this? i have an 03 with fass 165 and a sump kit. no visisble leaks anywhere that I can see. Thanks.
I have a 2002 lb7 214k miles zero blow by Last friday i drove the truck to work 11/3 it drove and felt fine i shut the truck off and worked a 12hr day came out and it cranks but no starts. It seems like its not getting fuel if i crank it for 10-15seconds then look out the pipe theirs zero raw fuel coming out. Has a code for glow plug circuit a and intake air heater but im in phoenix ambient temp is 60-85 degrees It wont even start with a squirt of ether. A buddy of mine thinks the cp3 died a slow death, due to me driving with a filter head loosing prime”aerating the fuel while driving” he advised me to put a lift pump which i did and got a week out of the truck before it died i pulled the fpr and lines on cp3 checked for metal shavings to see if it grenaded the pump zero metal shavings. One time when i plugged in a snap on solus scanner it said something about U1800 failure to communicate with ficm i cleared the code cranked it several more times code went away for that. Kinda lost at this point on where to further diagnosis it. Dont want to order the cp3 and do the job for it to still CRANK NO START PLEASE HELP I replaced the filter head and the glow plug module prior to my buddy telling me to pull the fpr and look in the pump for shavings.
I have a 2007 that sat through a cold snap and now will not start. No/low pressure to the schrader valve bleeder. Priming pump was mushy as well. I am guessing air in the system?
My LB7 is losing prime when hot and generally when the fuel tank is under 1/2 tank. On rare occasions it will die while at a red light. It generally happens after I stop somewhere and come back out to start it and it won’t start. I have to manually prime it to get it to start. Sometimes it takes two or three times to get it started and remain running. Recently, and again it is occasionally when it won’t start when cold. Again I have to prime it manually. Any ideas?
Hi my truck a 2003 duramax started having a long crank issue, but would start. I found that the fuel filter head was leaking a little fuel so I bought a rebuild kit for it and now it will just crank no start. I did the 15 second crank test to see how much fuel was returning and it was well under 100 ml. I also hooked up a scanner and it doesn't have enough pressure to start the truck. I am thinking failed cp3, but do they just fail like that? I had no other indication of fuel pressure surging at idle before hand. I also blead the system multiple times. I also replaced all the fuel lines from the tank and return lines with nylon lines. Also replaced the fuel cooler. Just wondering if you have any other information that I might be able to try. Thanks
I think your CP3 is airlocked. They typically dont fail like that. You can pressurize you fuel tank a little and see if you can get it to bleed that way (Assuming you have no lift pump?) Some guys will fire them up on either to get the rpms up. Sometimes thats enough to get a weak CP3 to make enough fuel pressure to run. Not my favorite option so do what you want with that.
I have an 08 Chevy Duramax put a new prime housing filter housing on truck still won’t start but if we push on the prime button it will start as it’s cranking do you have any ideas and when you shut it off and go to start it Again it won’t start until you push the button one time or twice
My 02 lb7 got a lil water in the ficm from the plug not being when radiator hose busted is what I’m guessing now the truck runs horrible loses prime and is putting oil in the coolant reservoir and diesel in the oil and is in limp mode take a good minute to start pretty much new injectors any guesses anything helps
If your putting diesel in the oil it’s gotta be something under the valve covers or the front seal on the cp3. Being there was injector work done I would bet you find a leaking return line under a valve cover. The rad hose and oil in the coolant is likely injector cup related. I have a video on that too. Good luck that sounds like quite a situation
My lb7 losses prime when its cold over the span of a few hours. One day, when it was exceptionally cold, i lost prime while driving twice. After dealing with this problem for a while the truck threw a p0088 code, and idiled very poorly, made it home (fuel pressure too high) and now wont start. Replaced filter and FPR, still no start
Mike, have you made sure to bleed the air from the lines with the bleeder screw while priming? You may also try priming while someone else turns the key, it’s worked for me in the past. If it’s cranking and not starting you’re just not getting fuel
I assumed the primer bulb would act as an anti backflow valve, but it sounds like that is not the case? My truck started ticking really bad out of the blue on startup one morning, like it had an instant injector failure. we shut it down and just started it a couple times to show a mechanic the sound, he agreed it sounded like injector failure. My plan was to pull the injector connectors off until we isolated the specific injector issue. Before we were able to, it started doing what yours did. We would have to prime it, it would load a slug of fuel then die within 2 or 3 seconds of running. If we pumped the primer it would go soft completely after about 10 seconds. I bought a whole new filter housing, that did not repair the issue. Does it sound like the injector could be bypassing so much that it would do that? Feels like I hit 2 different problems at the exact same time, now I don’t know how to diagnose either. I would hate to spend thousands on injectors and find it was a $5 tube causing everything.
I have a 2007 classic duramax and parking on flat ground and facing down hill it starts no problem whatsoever but the minute you park facing up hill after 30-1hr it starts for about 15 seconds then dies then you prime it and it runs no problem at all but shut if off for 30-1hr and the cycle repeats I have no idea where the leak is it’s like yours the fuel can’t get out but air is getting in and I’ve been chasing this for months and can’t solve it
Keep looking. Its gotta be there somewhere. You have to very carefully inspect every line from the tank all the way forward to the CP3 unfortunately. These trucks are wildly sensitive to air leaks
Good video for sure but the small tubing you replaced doesn’t have pressure on it with the truck not running right? Correct me please but I thought the CP3 was gear driven and would only build pressure when cranking and running. Teach me something
Well that didn't take too long to sort out ended up being a bad fuel line above the fuel cooler where the flex line from the feed side of the fuel tank meets the steel line 👍
I got a 2004 lb7 duramax, I went to fire it up to head to work started it fired up normal then as I was backing up it died so I tried to prime it and got nothing I primed it for ever and still couldn’t get a prime what could it be?
You either have a restriction or an air leak. Pulling some hoses off the filter housing and replacing them temporarily with clear tubing is a great tip to visually see if you have air or fuel flow. That will point you in the right direction.
I changed every damn hose there is. New fuel filter head, injectors are new, cp3 is new. I added an inline lift pump for more fuel pressure and I am still getting a no start. My primer is rock hard all the time. Even when I didn’t have the lift pump it still stayed primed. Maybe this is a main fuel line issue? Any help would be amazing.
Have the same problem with my lb7 but it dies when it’s hot outside and the ac on but when it’s cold outside it won’t do it. If it like 90 degrees out it will do it sometimes when I’m driving. Not sure any help would be appreciated
It sounds heat related. Hoses swell differently in different temperatures. Look over the entire system. You will see evidence of the leak it just may not be obvious.
I have a similar problem, extended crank and starts and dies sometimes. But if the tank is over 1/2 full it starts right up. It gets very bad under a 1/4 tank. I’ve been told it’s probably still an air leak like this but it’s hard to believe the truck runs and acts perfectly when you fill it up
My LB7 died suddenly under the hood on passenger side had been spayed with fuel looked like . Changed fuel filter it started ran 10min then died suddenly pumped filter was nearly full want start I can't find a leak anywhere? Help please
Diesel is tricky to find leaks. Rebuilding the fuel filter head/primer would be a good start. Clean it up real good and really study the system. If it leaked once it has to leak again
I like your design so that was cool. Now the fuel has to be filtered before it gets to the fuel rails and injectors. I want to see that diagram because I’m not seeing where the fuel gos into the engine. I assume but not sure that lines come off the CP3 and go to the fuel rails/injectors. Also what I learned here is that think is that the fuel is filtered before it even gets to the CP3
The cp3 is the last component to see fuel at low pressure. It pulls fuel from the tank, through the FICM, through the filter, then boosts pressure to 5000-26000psi. It’s got a hard line in the valley that feeds both fuel rails and the injectors.
Good video, I had a full set of fuel hoses sitting in the garage I ordered last year thinking they were going to need replacement from the looks of them. Had my first air pocket/no start today on my 2002. I'll be replacing them tomorrow.
Mine too... Fuel in the tank. Tank line is good. Primer is holding pressure. Must be this?? Also.. mine will choak n gag on occasion... For no reason.. just driving along. Doesn't seem to matter how much fuel is in it... Or the speed. Thoughts? Gotta be a pin hole?
04 lb7 brakes lock up while driving im limited to like 15miles all 4 wheels lock up, brake pedal hard as a brick at which point then i have to releave the pressure on brakes. 4 new calipers. Builds pressure while driving any ideas ?
If I had to guess this seems like a problem with your hydroboost. Or your pedal adjustment is incorrect not allowing fluid to return to the reservoir as the fluid heats up and expands. Does your brake fluid look like power steering fluid?
So what would be my problem if my fuel filter drains but won't start ....reprime .....same thing. But I can start it with starting fluid and it will stay running
2010 LMM, when my truck is between 1/2 and 1/4 it wont turn over (after sitting a hour or so) when the lift pump (FASS 150) is on, if i unplug the FASS and prime it manually it will run just fine until empty. Any ideas?
Good video, thanks for the the info. Question for you... My 03 LB7 threw a p0238 code for boost sensor so I replaced the MAP, I also recently replaced the TPS and the Baro sensor trying to chase down a p2227 code. Now it cranks but no start. Both batteries are brand new.... Any thoughts? Fuel system seems to be good, wires and fuses seem to be good.
You mean you replaced the throttle pedal? I would put a scan tool on it and see if its building rail pressure during cranking. You can check the injection pulse to see if its firing the injectors. For the 2227 you can also watch the baro on the scan tool and see if its reading or if its maxed High/Low you may have an actual circuit problem. Look for pinched wires on the engine harness its common if someone has been wrenching on it
I have the same problem on my truck, tomorrow I prove to repair the leak and check if all works good, thanks a lot man, and nice truck! best regards from switzerland!
My lbz just started loosing prime cant find rhe problem anywhere replaced the fuel filter with housing the sensor on the filter is not leaking. Replaced both lines going to the fuel filter housing. Cant see any leaks anywhere from the tank all the way to the fuel injectors its driving me nuts
Yes. Under heavy load mine would drag the air bubble into the CP3 and fall on its face but under low load the air bubble would stay at a high point, away from the cp3
Glad someone asked this. Although I saved this video, I bought 3/8" hoses. When i went back and looked i seen the hose was 1/2". The GM shop told me they were metric hoses though. 🤷♂️@@spankranchgarage
Dude, after 10 plus years losing prime and no one had a solution, I sent this video to my mechanic and problem solved. Thanks so much
Hell yeah! Love to hear it
Thank you so much for this video @spankranchgarage.
My 2005 LLY is doing the same exact thing. My hoses look a little suspect but I didn’t think they were bad enough to cause this. I will be doing what you did today in hopes it will work. Thank you for the video. Top shelf!
Will report back😢
I hope its an easy fix! Almost any hose in the system can cause similar results and they can be tricky to find
Shane any update?
Having the same issue with my 05 lly as well I’ve already replaced 3 of the 5 rubber hoses and it was fixed for a few days but now it’s happening again. I’ll let y’all know if it fixes it bc I’m living through the frustration of having a downed work truck
Mine was the filter housing...Replaced all the seals...The bad o ring was for the filter heater connection...
this just worked for me first time working on a duramax
Finally!!! I'm having the exact same issue on my 04. I had s feeling it was might be a hose, but i haven't ben able to find it. I'm foing to check that hose.
Really really appreciate guys like you that take the time to provide GRAET information. Thank you.
The fuel sender unit have a filter, changing it will solve many no start problems.
Awesome video, thank you sir. Having the same problem with my 04 3500. Ran fine yesterday after fuel filter change will not start now?
Great video !! Thanks for the information !! Very helpful
Excellent excellent 🎉🎉🎉❤❤❤. Huge help bud thanks!
Commenting on the video for the algorithm is
GREAT video!! Im having that problem now!!
My problem was the steel line coming out of the aluminum filter head. It was loose and allowing air to suck in instead of fuel. I removed the line by twisting and pulling. Cleaned it and JB welded it back in. Problem solved.
Nice! Crazy how many ways these fuel systems can fail us
Nice ass durmax. You keep that baby clean. Good job finding the leak
Really good advice for the people want to fixed self truck problems thanks for the advice and help with the duramax trucks
Perfect. Thank you
Great video, have the exact same problem on my 06 LBZ. Figured it was a tiny air leak, but I hadn't no idea what I'm looking at with that mess of wiring and lines. This helped a ton for where I should be looking and for what. I figured it would be a bigger leak than that. I probably wouldn't of even took a 2nd look at that hose.
This is the video I’ve been looking for! Thank you for the explanation at the end. My truck has been unable to smog for a month now due to P0101! I’ve already cleaned my filter and EGR, but noticed a second code now related to fuel pressure (p1093). From what I’m reading, this could be caused by a leak similar to this. Wish my luck on hunting it down. Thanks again.
So correct me if i'm wrong....
The leak was After the filter/primer assembly, but before the injection pump (cp3)?
Hey my 07 duramax, 2500hd. Found the suction line on drivers side 3/8” metal tube rubbed through rubbing against something 2 ft down from QD, GM flaw, many things rub and where on this model, even top radiator hoses and even the large wire QD hitting the cooler tube.
Hope this info helps the next victim
What is "QD"? -
My truck has the cat fuel filter on it. Never had this issue till the last time I spun a filter on now only if the truck is facing down hill it gets air locked
Sounds like a leak is allowing air to siphon in
This is great! Thanks..
My 2003 is not holding prime at all it won't start or run unless it is ether, and after hand priming it 10 minutes later, no fuel pressure. Could this be the same issue?
2013 chevy hd3500 6.6 losing prime replaced hose to Schrader valve but it ran but cut off
Mine prime is same.. soft... YOUR good
Nice fix, I have an 06 Duramax 3500 that starts and stops right away after sitting. I'll give this a look.
BEST VIDEO EVER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Mine is dry through out the truck, primer goes soft right away. Starts right up with starting fluid, and runs just fine. Could I have a leaking fuel injectors?
the issue is the primer pump assembly itself is the issue. The air leak is coming from the pimer pump oring seal on the pump allowing air to enter into the fuel line which causes the air into the fuel rail to the injector. The primer pump needs to be replaced or rebuild the primer pump. The hose clamp you used is toooooo large for the hose needs clamping which will cause leaks. NEVER use BRAKE CLEANER on ANY rubber parts which causes the rubber to become hard and brittle..
1:56 if you can already see fuel around your brass screw that should be plastic, thats a leak. the plastic will self seal when tight. brass wont. anyway if this has a leak, you lose prime also
Yes a leaking bleeder can cause problems too. The brass screw has an o-ring and seals just fine. Lots of residue from previous bleedings.
@@spankranchgarage ah makes sense. and even with the oring i have seen them leak, the oring that comes on them is cheap af.
Thank you for your time! Great explanation!
Same exact issue with my 04.5 lly. I got a fass on it that sounds like shit so I’m wondering if that’s what it is. But it’s got a fuel pressure gauge and it shows 0 until I prime it up before starting
Have u figured it out mine is doing the same thing
Same... any suggestions?
Lb7 turns on at cold start but when the truck is hot it will crank till the batteries die. But if I spray some starter fluid it starts
Did you put a scanner on it and watch rail pressure vs commanded rail pressure? Does it make good power once its running?
If you ran a smoke machine through the fuel line near the tank, do you think that smoke would have come out of that leak? I'm having a similar problem but after replacing the CP3, the FRPS, the fuel filter housing, and the hoses coming off the fuel filter housing I still get VERY low ACT fuel rail pressure on crank. Like 7 of 38 desired (on live data) no codes and if I give her a little ether bump, she will start and run perfectly. Shut her off and attempt to restart her and she will only crank no start.
I was thinking about this too. I think if you blew the lines out so theres no fuel pockets blocking the smoke it would work. You can also disconnect the lines at the tank and lightly pressurize the system and check with soapy water. Last option would be to see if anyone makes a UV dye for fuel that wont hurt anything... like leak checking an AC system. These systems are tricky. The smallest little leak wreaks havoc, as you are experiencing.
This is the exact same issue I am having except if I push the primer when the truck starts to die it will keep running, did you try to do this? i have an 03 with fass 165 and a sump kit. no visisble leaks anywhere that I can see. Thanks.
I didnt try that but it probably would of worked. These leaks are insanely hard to find because sometimes fuel doesnt leak out and only air leaks in.
priming pump on top of filter housing . fixed mine and my sons truck .
My 2002 was doing the same thing and it was actually the FICM leaking from the back epoxy sealant.
Thats a new one I have never seen. Good find.
Same truck but when pumping primer Ik not geting any fuel to it. Tanks full any guesses ??
GREAT video sir. thanks
Where can I find a diagram or a video on all the fuel lines on this truck?
Installed XDP Duramax Cat adapter fuel filter on 2016 gmc Duramax. Per instructions. Bled fuel system. Truck won’t start.
I have a 2002 lb7 214k miles zero blow by
Last friday i drove the truck to work 11/3 it drove and felt fine i shut the truck off and worked a 12hr day came out and it cranks but no starts. It seems like its not getting fuel if i crank it for 10-15seconds then look out the pipe theirs zero raw fuel coming out.
Has a code for glow plug circuit a and intake air heater but im in phoenix ambient temp is 60-85 degrees
It wont even start with a squirt of ether.
A buddy of mine thinks the cp3 died a slow death, due to me driving with a filter head loosing prime”aerating the fuel while driving” he advised me to put a lift pump which i did and got a week out of the truck before it died i pulled the fpr and lines on cp3 checked for metal shavings to see if it grenaded the pump zero metal shavings.
One time when i plugged in a snap on solus scanner it said something about U1800 failure to communicate with ficm i cleared the code cranked it several more times code went away for that.
Kinda lost at this point on where to further diagnosis it. Dont want to order the cp3 and do the job for it to still CRANK NO START PLEASE HELP
I replaced the filter head and the glow plug module prior to my buddy telling me to pull the fpr and look in the pump for shavings.
Did you get this figured out? 🤔
I have a 2007 that sat through a cold snap and now will not start. No/low pressure to the schrader valve bleeder. Priming pump was mushy as well. I am guessing air in the system?
Would this cause truck to idle rough and surge? My LLY is loosing prime over night
Yes. If its drawing any air into the line the CP3 regulator circuit will not regulate fuel pressure adequately.
My LB7 is losing prime when hot and generally when the fuel tank is under 1/2 tank. On rare occasions it will die while at a red light. It generally happens after I stop somewhere and come back out to start it and it won’t start. I have to manually prime it to get it to start. Sometimes it takes two or three times to get it started and remain running. Recently, and again it is occasionally when it won’t start when cold. Again I have to prime it manually. Any ideas?
Hi my truck a 2003 duramax started having a long crank issue, but would start. I found that the fuel filter head was leaking a little fuel so I bought a rebuild kit for it and now it will just crank no start. I did the 15 second crank test to see how much fuel was returning and it was well under 100 ml. I also hooked up a scanner and it doesn't have enough pressure to start the truck. I am thinking failed cp3, but do they just fail like that? I had no other indication of fuel pressure surging at idle before hand. I also blead the system multiple times. I also replaced all the fuel lines from the tank and return lines with nylon lines. Also replaced the fuel cooler. Just wondering if you have any other information that I might be able to try. Thanks
I think your CP3 is airlocked. They typically dont fail like that. You can pressurize you fuel tank a little and see if you can get it to bleed that way (Assuming you have no lift pump?)
Some guys will fire them up on either to get the rpms up. Sometimes thats enough to get a weak CP3 to make enough fuel pressure to run. Not my favorite option so do what you want with that.
@@spankranchgarage thanks for the response. It doesn't have a lift pump. I will try some propane instead of starter fluid.
fuel sender unit? try to bypass fuel tank using a 2 gallons tank and 3/8" 1/2 hoses
I have an 08 Chevy Duramax put a new prime housing filter housing on truck still won’t start but if we push on the prime button it will start as it’s cranking do you have any ideas and when you shut it off and go to start it Again it won’t start until you push the button one time or twice
My 02 lb7 got a lil water in the ficm from the plug not being when radiator hose busted is what I’m guessing now the truck runs horrible loses prime and is putting oil in the coolant reservoir and diesel in the oil and is in limp mode take a good minute to start pretty much new injectors any guesses anything helps
And great video by the way loved u explain what ur doing and y as best as u can
If your putting diesel in the oil it’s gotta be something under the valve covers or the front seal on the cp3. Being there was injector work done I would bet you find a leaking return line under a valve cover. The rad hose and oil in the coolant is likely injector cup related. I have a video on that too. Good luck that sounds like quite a situation
My lb7 losses prime when its cold over the span of a few hours. One day, when it was exceptionally cold, i lost prime while driving twice. After dealing with this problem for a while the truck threw a p0088 code, and idiled very poorly, made it home (fuel pressure too high) and now wont start. Replaced filter and FPR, still no start
Are you able to monitor rail pressure when you are cranking it?
Mike, have you made sure to bleed the air from the lines with the bleeder screw while priming? You may also try priming while someone else turns the key, it’s worked for me in the past. If it’s cranking and not starting you’re just not getting fuel
I assumed the primer bulb would act as an anti backflow valve, but it sounds like that is not the case? My truck started ticking really bad out of the blue on startup one morning, like it had an instant injector failure. we shut it down and just started it a couple times to show a mechanic the sound, he agreed it sounded like injector failure. My plan was to pull the injector connectors off until we isolated the specific injector issue. Before we were able to, it started doing what yours did. We would have to prime it, it would load a slug of fuel then die within 2 or 3 seconds of running. If we pumped the primer it would go soft completely after about 10 seconds. I bought a whole new filter housing, that did not repair the issue. Does it sound like the injector could be bypassing so much that it would do that? Feels like I hit 2 different problems at the exact same time, now I don’t know how to diagnose either. I would hate to spend thousands on injectors and find it was a $5 tube causing everything.
I have a 2007 classic duramax and parking on flat ground and facing down hill it starts no problem whatsoever but the minute you park facing up hill after 30-1hr it starts for about 15 seconds then dies then you prime it and it runs no problem at all but shut if off for 30-1hr and the cycle repeats I have no idea where the leak is it’s like yours the fuel can’t get out but air is getting in and I’ve been chasing this for months and can’t solve it
@sparkranch garage
Keep looking. Its gotta be there somewhere. You have to very carefully inspect every line from the tank all the way forward to the CP3 unfortunately. These trucks are wildly sensitive to air leaks
Good video for sure but the small tubing you replaced doesn’t have pressure on it with the truck not running right? Correct me please but I thought the CP3 was gear driven and would only build pressure when cranking and running. Teach me something
Correct, unless the truck is fitted with a lift pump as mine and many are. Low pressure 8-12psi typically
@@spankranchgarage Yes, I forgot about that. Good job! I also need to get a lift pump because it allows finding any leak much easier with pressure
I am just embarking on the same problem thank you for pointing me in the right direction I will let you know how this goes❤
Well that didn't take too long to sort out ended up being a bad fuel line above the fuel cooler where the flex line from the feed side of the fuel tank meets the steel line 👍
Glad you fixed it!
Mine wont hardly stay running and its doing mostly the same but it sounds a bit rougher at idle im not sure tbh
Might be a bigger air leak
I got a 2004 lb7 duramax, I went to fire it up to head to work started it fired up normal then as I was backing up it died so I tried to prime it and got nothing I primed it for ever and still couldn’t get a prime what could it be?
You either have a restriction or an air leak. Pulling some hoses off the filter housing and replacing them temporarily with clear tubing is a great tip to visually see if you have air or fuel flow. That will point you in the right direction.
I’m having the same issue but after running for a bit giving it throttle it died, lost prime and now is a crank no start
I changed every damn hose there is. New fuel filter head, injectors are new, cp3 is new. I added an inline lift pump for more fuel pressure and I am still getting a no start. My primer is rock hard all the time. Even when I didn’t have the lift pump it still stayed primed. Maybe this is a main fuel line issue? Any help would be amazing.
Have you watched your rail pressure and desired rail pressure with a scan tool while cranking it?
Have the same problem with my lb7 but it dies when it’s hot outside and the ac on but when it’s cold outside it won’t do it. If it like 90 degrees out it will do it sometimes when I’m driving. Not sure any help would be appreciated
It sounds heat related. Hoses swell differently in different temperatures. Look over the entire system. You will see evidence of the leak it just may not be obvious.
I have a similar problem, extended crank and starts and dies sometimes. But if the tank is over 1/2 full it starts right up. It gets very bad under a 1/4 tank. I’ve been told it’s probably still an air leak like this but it’s hard to believe the truck runs and acts perfectly when you fill it up
1/4 issue . See a sump with ur lift pump
My LB7 died suddenly under the hood on passenger side had been spayed with fuel looked like . Changed fuel filter it started ran 10min then died suddenly pumped filter was nearly full want start I can't find a leak anywhere? Help please
Diesel is tricky to find leaks. Rebuilding the fuel filter head/primer would be a good start. Clean it up real good and really study the system. If it leaked once it has to leak again
I like your design so that was cool. Now the fuel has to be filtered before it gets to the fuel rails and injectors. I want to see that diagram because I’m not seeing where the fuel gos into the engine. I assume but not sure that lines come off the CP3 and go to the fuel rails/injectors. Also what I learned here is that think is that the fuel is filtered before it even gets to the CP3
The cp3 is the last component to see fuel at low pressure. It pulls fuel from the tank, through the FICM, through the filter, then boosts pressure to 5000-26000psi. It’s got a hard line in the valley that feeds both fuel rails and the injectors.
3 months in and still holding pressure !
Great to hear! Nice work!
Good video, I had a full set of fuel hoses sitting in the garage I ordered last year thinking they were going to need replacement from the looks of them. Had my first air pocket/no start today on my 2002. I'll be replacing them tomorrow.
Sounds like its time! Good luck
Great work thank you!
Mine too... Fuel in the tank. Tank line is good. Primer is holding pressure. Must be this?? Also.. mine will choak n gag on occasion... For no reason.. just driving along. Doesn't seem to matter how much fuel is in it... Or the speed. Thoughts? Gotta be a pin hole?
If the primer stays hard I would bet your problem is between the tank and the primer. It will cause a choke and gag too.
Those clamps are too big.
Yes they are
04 lb7 brakes lock up while driving im limited to like 15miles all 4 wheels lock up, brake pedal hard as a brick at which point then i have to releave the pressure on brakes. 4 new calipers. Builds pressure while driving any ideas ?
If I had to guess this seems like a problem with your hydroboost. Or your pedal adjustment is incorrect not allowing fluid to return to the reservoir as the fluid heats up and expands. Does your brake fluid look like power steering fluid?
So what would be my problem if my fuel filter drains but won't start ....reprime .....same thing. But I can start it with starting fluid and it will stay running
It sounds like a bigger leak to me that cannot be overcome at cranking RPM, but it finally primes once the engine is running in ether
Do you know anyone who can tune a LB7 that has HP tuners all ready installed in Los Angeles area?
I do not, sorry
My 08 sounds like this
2010 LMM, when my truck is between 1/2 and 1/4 it wont turn over (after sitting a hour or so) when the lift pump (FASS 150) is on, if i unplug the FASS and prime it manually it will run just fine until empty. Any ideas?
That's a really strange one man. Usually the FASS will help mask the symptoms of leaks, not make it worse. Im not sure whats going on there
Tell me about it. I bled it with the lift pump and I think that was the ticket. Maybe just some stubborn trapped air.
Good video, thanks for the the info.
Question for you...
My 03 LB7 threw a p0238 code for boost sensor so I replaced the MAP, I also recently replaced the TPS and the Baro sensor trying to chase down a p2227 code. Now it cranks but no start. Both batteries are brand new.... Any thoughts? Fuel system seems to be good, wires and fuses seem to be good.
You mean you replaced the throttle pedal?
I would put a scan tool on it and see if its building rail pressure during cranking. You can check the injection pulse to see if its firing the injectors.
For the 2227 you can also watch the baro on the scan tool and see if its reading or if its maxed High/Low you may have an actual circuit problem. Look for pinched wires on the engine harness its common if someone has been wrenching on it
@@spankranchgarage Yea the TPS is in the pedal assembly.
Thanks for the tip.
I have the same problem on my truck, tomorrow I prove to repair the leak and check if all works good, thanks a lot man, and nice truck! best regards from switzerland!
Good luck! I didn't know there were any Duramax trucks in Switzerland!!
yeah, not many but there are, two are from me and my neighbours@@spankranchgarage
My lbz just started loosing prime cant find rhe problem anywhere replaced the fuel filter with housing the sensor on the filter is not leaking. Replaced both lines going to the fuel filter housing. Cant see any leaks anywhere from the tank all the way to the fuel injectors its driving me nuts
Same here... Did you find it?
@georgehofgren6123 had 3 injectors leaking down when hot but only when sitting.
@@TheMoody876 Thank you 😊
Would this cause a complete no start condition?
Yes absolutely
Could that cause a build up of air over time driving and cause stunbling?
Yes. Under heavy load mine would drag the air bubble into the CP3 and fall on its face but under low load the air bubble would stay at a high point, away from the cp3
Man these back to back videos. This is awesome
Good video
My 2004 LLY has this problem on very hot days, definitely going to look into this. Thanks for the video.
Good luck thanks for watching!
@@spankranchgarageThis was the trouble, after i fixed it this summer it starts IMMEDIATELY........I'm still stock with no lift pump.
So is it all 1/2" fule line for all the rubber line ???? Thanks
For most of the hoses yes 1/2"
Glad someone asked this. Although I saved this video, I bought 3/8" hoses. When i went back and looked i seen the hose was 1/2". The GM shop told me they were metric hoses though. 🤷♂️@@spankranchgarage
My wife has a problem in which her car is complaining about a timing belt.. maybe you can take a look.
I don't see how this is related to diesel fueling issues? lol
Add a air dog lift pump
I have an airdog. Works great but masks any leaks in the system. Works best when the system is tight
@@spankranchgarage it works better then beating your head against the wall
Glad I don’t own a dirty mac
I'm glad I don't own a powerstroke .
@@brockstephens3271 you mean a power joke