Trying to Diagnose M925A1 Fuel Problems
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- Опубликовано: 8 сен 2024
- When it rains it pours right? Now the truck has developed a fuel fault. Either I have a failing lift pump or I have a bad fuel shut off solenoid. Given the symptoms I am leaning to the solenoid. That might be because of the relative prices between them but still a low pressure gear driven injector lift pump would fail like a hydraulic pump right? A slow drop off of pressure not coming and going like a switch?
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Sometimes the fuel shutoff solenoid gets rusty. Take it apart and clean out the corrosion.
ah and as far as the feed PSI, the PT pump produced 25psi at idle and under max load they will produce between 160 and 170psi unless you have changed the button to increase the pressure.
yes ,thats your problem mind did the same thing. put a new solenoid on it and it will be as good as new
I experienced that on a gas engine. after many hrs diagnosing I discovered a match book cover with the staple and matches removed floating in the fuel tank. after running the engine it would then get sucked up against the inlet of the metal tube feeding the pump and starve for fuel. after it sat awhile it would lose pressure and run great until the match book cover would find its way to the end of the tube again. but i do like what the welder suggested.
+TheDrywallogist What a strange issue to find.
When I drove these trucks in Marine Corps, thier were two trucks that I had same issue with and motor pool changed those solenoids, afterwards I never had the same issue. So I would say you are correct.
Just fyi it may be a few years late but there is not "needle" valve in the shutoff solenoid. Its a metal disk that opens and closes with magnetism..
I am sure u checked this... but fuel filter first. Then check for buildup inside metal lines. If rubber lines are present, they can decay on inside and allow junk to drift off and float or flap. A way to test piping would be to disconnect fuel line and measure the flow rate. Another possibility could be a weak hose that is collapsing under pressure or temp. Especially if the hose is already at an angle... additional heat can cause it to flex or collapse.
Coming back to this video to say something about issue i came across with my m925, i had problem simialr to this again, but after few times of dieing over and over, it then stuck idleing at 1300 rpms, i took the bell shaped housing off the pt pump and pulled apart the guts and found that the button was sticking in and out, slight coat of rust from sitting on inside of the button holder so that the button wasnt able to slide back and forth, after cleaning up and putting back together, i havent had any issues.
I will have to give this a try next time.
With the ULSD now and all the emission bs most diesel fuels are "dry" we add a quart of regular non detergent 30 weight oil or ATF to every 50 gallons of diesel to run in our older diesel engines on the farm. We had problems with stuff like this when they would sit through the winter and this seemed to solve it.
TheWelder7018 Ok, I will try that. Would a lubrication oil designed for fuel like say 2 stroke oil work?
NelsonStudios yes that will work
I add a bottle of 2 stroke to my chevy tank to help lube the injection pump
NelsonStudios don't use 2 stroke oil. Use ATF on occasion.
Ive had that problem a couple of times on trucks that have done a lot of sitting i just whack the solenoid with a hammer p.s. the old 855 in those a1 tucks are a lot better than the new ones
When it’s running badly does it take its time to decelerate also ? Could be a few things going on here. If you forgot to install the center square
o ring up on the fuel filter, or there is two up there because the old one wasn’t removed before the new one was installed will cause the fuel
supply to suck air. The throttle shaft and governor carrier assembly could be pooched. The stand pipe / pickup pipe in the fuel tank could
be cracked, OR ! Look in the fuel tank and see if there is anything like a shop rag, or other debris floating around at the bottom of the tank,
that can get sucked up into the stand pipe, then when the engine stops, the suction stops and the object float’s away from the pipe until you
start it and it is drawn back to the suction pipe again. Saw this when an owners child dropped a dolls dress in the tank. I’m concerned when you
mention people in the same sentence as hills ? Supposing you have a load of people on board and your engine quits, now you can’t build up
air for the brake system, then what ? Get everyone to drag their feet ? Good luck, and god bless I guess 😮
It turned out to be egt so high the pistons started to stick in the bores. Combination of long hills, trying to maintain road speed, no oil cooling of liners. I know they're famous for sucking air.
These trucks don't have a lift pump. The injection pump has to draw through the filter. The point is that if you pushed air through it a collapsed or failing line will not be noticed. My first start would be the fuel system, looking for small cracks in the line that would suck air or weak lines to collapse. Check my videos and email me if you need any help, I have worked to make myself an expert on these injection systems. kennys@wi.rr.com
what kind of fuel do you run. the fuel is very dry now run a quart of atf in say every 30 -50 gal of fuel and it will clean up that stick solenoid. the truck was not meant to run on such dry fuel. i have a friend that has had the same thing with a cumming in his 90's 4 wheel drive tractor and that's all he did to fix it.
mog5858 Does it matter what atf? I have some old type f that I will never use again.
mog5858 I agree on the ATF. Used lots of it through the years. For pre-emission enginges only. It's a cheap try and won't harm anything. After up and running, it wouldn't hurt to add a quart to 50-100 gallons every now and then. Current diesel doesn't have the lubricity that the old fuel did.
NelsonStudios you just trying to get some lube in to the things that like to be lubed. i don't darken their door but what every cheap at wal-mart will work just fine.
check the wiring circuit for the fuel shut-off, sounds like a loose connection or a broken wire. if it happens again run a jumper wire directly to the battery or a known power source.
stephen feldmeier Did you ever find the problem? You mentioned "key" did you install a keyed ignition switch? The very detailed information you gave leaves only 3 areas, as you have an electrical problem. Either the ignition switch is bad (loose connections on the inside) the wiring to the solenoid has a loose connection or the solenoid itself has an internal loose connection. If you did not find a problem and the truck is running fine (like it fixed itself) well you know as well as I do electrical problems are intermittent that always come back to haunt you at the worse time.
stephen feldmeier It has. We have located noting and unfortunately each I I worked on it we tried several things. I have not lost all power again like it was doing but I have had it hesitate. I keep coming back to something in the tank. I cut slots in the fuel pickup close together like a strainer for about the bottom two inches. Figured if something was blocking it it would be hard to block all of that at once. No issues since then but I am not claiming that as the culprit yet. I have also been told that on these motors a small air leak will not always cause them to rev up like I thought so it could be an air leak that I now have sealed. Since it never lost prime I still don't think that is what was wrong.
@@acme663ryo what if u lost prime ?
@@acme663ryo do u have to bleed the air out of th÷se an if so do u know how
I know this is a very old video but I’m having the same problem and I’m just curious what ended up being the solution ??
It ended up not being fuel. The civilian version of this motor has oil cooling passages to the base of the piston liners. Uncle Sam cheaped out. The small valves and no turbo leads to crazy high egt. Pistons were starting to stick. Put a pyro on your truck asap. Otherwise most common fuel issues I have run into are air leaks on the suction side the pull air when hot and the manual shutoff valve getting bumped
All the 855 block 250’s don’t come with pistons cooling, except maybe the “ Super 250 “ which is a different block, longer stroke and 4 bolt rod
caps. They weren’t in production long, NTC 290 ‘s took over that segment. 290 was a good engine. 👍
Did you have a full tank of fuel with a non vented gas cap...that will do it.
Maybe running some kind of diesel fuel system cleaner through would help?
DRWebster93 That seems to be a common idea, I will give it a try.
I'm currently have trouble with my ntc , my problem was a pressure feed line was leaking and not running smooth even at idle, Now I cant get it started period, tried opening solenoid button and closing it , and I have refilled fuel filter 4 times after turning engine over to start, tells me pump is pumping fuel from tank , any ideas ???
First make sure you haven't bumped the manual shutoff, been there. Crack the line right at the injection pump inlet and pressurize the fuel tank using an airline and a rag to seal. Make sure you have fuel at the pump then go injection line to injection line bleeding
@@acme663ryo 🤔 loosen the pressure line From Solenoid that leads to block head and then pressurize with air from fuel tank to see if fuel is passing through the solenoid?? With Button screwed closed Or wide open ??
@@phillipchavez755 start just after the fuel filter and work your way up. Before you start pull the manual kill cable in the dash and then reset the manual valve. In is to override the solenoid. You can energize with a jumper and feel if it is working.
@@acme663ryo 🤔 okay , now can you Feel By Touch the Solenoid clicks when you turn the key ?
This engine does Not have a kill cable kill switch ,
But I will loosen a fuel connection Before Solenoid and From Solenoid to see if fuel is being pumped up to heads , thank you for your input
@@phillipchavez755 you do not have a small manual valve handle above, below or on the solenoid? Where is your manual shutoff located then?
Did this turn out to be the problem? I had a truck that my coworker connected batteries incorrectly and ever since then truck has no power. Everyone says to check fuel system but everything worked perfectly before battery incident. Basically my coworker connect four 6v batteries in series and turned key on and started... all gauges maxed out and he asked me why they were doing that. I asked him if he took pic or had sketch of battery terminal position but he didn't and said he guessed at terminal locations haha.
So he hit it with 48v? I replaced the small ground wire off the starter with a slightly larger one and have never had an issue again. Old wire felt soft in places, you can run your fingers over and flex the cables feeling for some place where they might have melted inside the insulation. If you are 100% dead, no power at all check that you have 24v at the starter, then check you have 24v going into and out of the upper main switch, then into and out of the lower. No wait, if it clicks the abs solenoids at power on then the switches are working. No abs clicks then you have an issue before switches.... or the abs is blown out of it. Feel fee to contact me directly with more details and I am sure we can work through it.
NelsonStudios did those checks and it looked good. I moved one of the wires that comes to the alternator to the 2nd battery instead of the 4th battery... now truck started but has very little power now.
Could the fuel cutout solenoid have burnt out?? Other then power issue, everything seems to work especially the gauges haha. There acting normal now.
Not if it started, fuel solenoid is fine. If you suspect then turn the knob on it all the way in by hand and then the motor is just 'on'. Switching the wires from one battery to the other should have had no effect at all, go through loosen, wiggle and retighten each of the battery terminals and each end of any engine/frame/body ground strap you can find. If you have the time unhook one side of each of the batteries and let them sit for a few days. Measure the voltage and see if you have a dead one, very possible with a reverse hook up. One dead battery in the four will cripple the others. You only need two to run it so if you have a bad one then you can go for a long time with just the two best ones.
I take it back, I am not sure what very low voltage will do to the solenoid in terms of power. Turn the knob in and test again.
NelsonStudios ok ill get back at it in the morning. Ill keep yah informed so thank you for help!!!
built on a government contract so designed to make max profit and with no care at all for quality.sounds like all the profiteering military industrial complex would do as usual.just get a normal civilian designed truck and u wont have the problems.
i think he's a glutton 4 punishment, lmfao, 🤣😅