WOW,what a good video. Lots of information on the L98 fuel system that's not difficult to understand. You are such a detailed and meticulous person, one of the few left. Nice work, Sir.
Incorrect explanation. Here is the correct one. The oil switch is not a requirement, it is only a backup for a failed relay. ruclips.net/video/IYgH5lkYoFI/видео.htmlsi=qaM6HO4-uzz9UhyV
Purchased a 90 C-4 convertible very low mileage and issues inherited with a car that has associated problems from not driving . Great to see the flow charts " Army style " hoping to to see some solutions . Great site!
Very well done video. I just subscribed to your channel and will be looking for future videos from you. I am currently experiencing an intermittent fuel delivery problem with my 1990 C4.
Having just replacing all of my injectors it started about 30 seconds sputters but finally ran very well but noticed when I parked the car I would have to wind the engine for a about 30 seconds again to start the car again other wise the car runs better than it had not knowing actually how good this car runs ! This will be my next step.
Nice video ❤😊 I bought a new relay and it still doesn't want to start. But when I put direct power to the fuel pump. The car will start...but once I remove the direct power from the fuel pump....it shuts off..
Ok that could be tricky. First off double check your fuses for the fuel pump. If fuses are good then most likely a wiring issue. Bad connection somewhere.
CHANGED THE RELAY AND THE NEW FUEL PUMP, THE NEW FUEL PUMP DIDN'T WORK. I saw another video with someone adding a C6 fuel pump. This is making me and my mechanic crazy
Great video. I think my 93 relay is bad. I don’t hear the fuel pump priming when the key is in the start position. What are the symptoms of a failed relay? My car will click on the first attempt to start the car. The second attempt cranks the car but will not start. It sucks because my car is stuck in the garage and I need to push it out to get to the fuel pump relay.
Hey thanks for reaching out, the relay only does the priming. If the fuel pump is working when you crank to engine long enough the pump should build pressure and the engine should start without the relay. There are 2 circuits in play here. The real test would be to see if you are getting fuel pressure. A simple test is to shoot some starter fluid into the trottle body and start the car to see if the engine will fire. If the fuel pump is working the car should remain running. You can reach me at: justcorvettecrazy@gmail.com
Hey boss so I just replaced the relay and the Fuel gage only builds up pressure when cranking it and then it just lets the pressure go and also when I am on running position fuel pressure does not build up I can’t start by corvette at all do you have any advice??
Thanks for reaching out. You can reach me at justcorvettecrazy@gmail.com. Maybe we can figure it out together. If it is not holding pressure there are a few options we can look at. What year is the car?
If I have power at the connector at the back of the car and no fuel pressure on a gauge on the rail, is it most likely my fuel pump? (new filter and pressure side line has been blown out)
Thanks for reaching out. If you are correctly measuring voltage at the connector at the right time then yes fuel pump could be bad. One sure way to check is to remove the fuel pump and test it outside the car by putting 12V power to the connector to see if it runs.
Another question, I'm working on a '91 convertible. I bought it in Jacksonville without a steering wheel, ECM, throttle body and a couple other things. I replaced all this with a '91 wreck I didn't have insurance that I bought my son and he went through the woods backwards. I replaced all this including the ccm, so it all matches. It was running a little rough, but I had to stop and now I'm back on it after a couple of years. I continued to start it about once a month or so. Now it won't start. I had put a new fuel pump in a while back, now I replaced that one and took the pulser off and replace it with hose. I replaced bladder in the pressure regulator, even thou I had 40 lbs, just didn't know how long it had been there. It's still the same, no start. What confuses me is I press on the valve on the fuel rail and fuel just flows out slowly with the 40 lbs of pressure, thought I remember it spewing out, it's like no pressure on the rail. that's my concern?????
Hey Mitchell, I am assuming you used a fuel pressure gauge to test the pressure at 40psi at the valve. If so fuel should be there. First thing to do is spray starter fluid into the throttle body. If she starts then you know you have a fuel delivery issue and we can go from there. Try that and get back to me. you can email me direct at justcorvettecrazy@gmail.com
This was the exact issue i had. How did u know about the 4psi of oil pressure thing? Without this video id still be trying to figure it out. Replaced the fuel pump for no reason lol.
Thanks for the nice comment. I read about it, I think maybe in the service manual while looking for a C4 start sequence. Glad the video helped you out.
Mine was 1986. ECM is located under the dash on passenger's side. For your car they moved the ECM out to engine bay so your Fuel Pump Relay should be located inside passenger side behind the glove box area. They changed it for 91.
I have an odd problem. I replaced the fuel pump and the relay. Car was running. Sat for about a month and now won't run. I checked the fuse panel out and I'm getting the voltage to the fuel pump fuse location. However with a fuse in it. I get no voltage out of the fuse after I put the fuse in. Do you think my fuel pump regulator may have gone bad because I'm kinda lost as to why I would get the current from the panel but not from the fuse? Yes the fuse is new also. Thanks
Thanks for reaching out. What year is the car? It is hard to comment on your voltage when I don't know how you are measuring it. Here is what I would do. Unplug the connector to the fuel pump on top of the tank. Hook up your volt meter there. Then turn the key to the run position and you should get 12Volts for 2 seconds. If you then try to start the car you will get 12Volts while the engine is cranking. If that is the case then the voltage part is fine. See this video at the 13 minute mark.for measuring. ruclips.net/video/JGC1eeOgoYA/видео.html
On one of your videos you mentioned a 90 degree adaptor for your fuel pressure regulator. I've asked the oldest part stores in town and they can't tell me, I've searched ebay and maybe I don't know what the wording is to search for one. Can you tell me where I can buy one?
There are a couple of options if you look at Rockauto. Verify by your year, I am not 100% sure if the relay changed over the run of the car. I know it did for other relays under the hood. If you want to go OEM I can help you find a number. Let me know if you have any other questions. Cheers.
Looks like this may be my problem. As I've had hard starts when cold. And I don't get fuel pressure with key "on". Though I get fuel pressure when cranking and I get 38psi at idle. I was really dreading having to replace the fuel pump. But I'll put in a new relay and see what that does. As I'm betting it's that as that explains no fuel pressure with key "on", but I get fuel pressure when cranking and at idle, etc.
Hey I have a 92! I have a new opti. New fuel pump relay..not getting spark to the main coil or gas from hoses. Opti not sparking when turned?? Any suggestions please?
Do you have a fuel pressure gauge? When you turn the key to the run position the fuel pump relay should run the fuel pump for 2 seconds and build up pressure for the start. If that is not happening, check the relay. If you need more info email me at justcorvettecrazy@gmail.com and we can work it out together.
My 1987 Corvette spudders and doesn't have much power during acceleration. I've only experienced a hard start once a few weeks ago. I took the fuel pump relay switch apart the other day and the connection terminals were filled with old black grease. I cleaned the terminals with electrical cleaner spray and put back together. Still the car spudders while running, and I do not hear the fuel pump make any noise during the 1st few seconds of turning key to the on position. Is my issue the relay itself? The car seems like it's running on 7 cylinders instead of 8. I ordered new plugs, wires, cap and rotor. (Haven't recieved them yet.) However I'm thinking the fuel pump relay switch could be the issue with loss of power aswell. Any insight would be appreciated. Thanks!
Fuel pump relay only operates for 2 seconds to prime the fuel rails so it would not be your main problem. After those 2 seconds the ECU takes control of the fuel pump. 1 thing you need to check is your fuel pressure. Loss of power sounds like loss of fuel pressure. If that is the case there are 3 parts to consider, weak fuel pump, plugged fuel filter or leaking fuel regulator.
@@justcorvettecrazy116 thanks for the fast response. You have some very good info on the c4s. The engine does start right away. However the engine spudders and has slow acceleration. Check engine light goes on after a hard acceleration once every few days. Code 32 and 43 are stored in the check engine light. Code 32 is the egr valve I have 1 on the way from ebay for $50. Code 43 is the electronic spark control sensor, I know that most people say change the knock sensor and wiring to it. But is it possible that a fouled spark plug or old spark plug wires could trigger a code 43 and cause loss of power, engine spuddering during acceleration, and a rough idle? The engine has not stalled, just weak power. I'm hoping my issue is a tune up. But with all these relays, sensors, and possible bad fuel pump. I'm not sure and nervous I'm heading down the wrong path. The car has 75,000 miles on it and is an 87 c4. And I just put a new ac delco o2 sensor in 4 days ago. It did nothing to resolve my issue. I will have the tune up parts in a few more days aswell as new egr valve. If these items fail my hopes and dreams of this Corvette coming alive again; I'll be checking fuel pressure and pump immediately after tune up. Thanks!
3 possibilities - 1. faulty check valve in fuel pump 2. leaky/faulty fuel regulator 3. leaky injector. If you want to email: justcorvettecrazy@gmail.com I can help you with some tests.
Unfortunately my c4 won’t start!! I changed fuel pump, fuel sending unit, please anyone if you have any ideas please let me know. Been dealing with this since last December.. it turns over but won’t start. Acts like it wanna start but just don’t!! 88 with 71,000 miles
Hello, i have exactly same symptoms as bad relay has BUT it works. What would be next thing to look at? Cold start takes ages and hot start is almost instat. Idle kinda wandering 7-12k
First thing is to check fuel pressure to see if the pressure is staying when you put the key in run. If the pressure goes up to mid to high 30's and then falls quickly you have a pressure leak. Could be fuel pump check valve or fuel regulator. You can email me at: justcorvettecrazy@gmail.com if you need more advise.
I just got my new to me 1986 C4 (47,000 original miles) going this morning. It hadn't run in 7-8 years and various people appear to have worked on it's issues. I followed the procdures shown in this video and quickly determined a bad fuel pump. When I removed the fuel pump from the tank and applied 12 volts to what I thought was the motor the fuel gauge resistor smoked (a lot). I disconnected the electric wire from the rheostat and then put power to the pump and it worked. I took the car for a drive. I'm not sure what exactly happened. Anybody got any thoughts on why the faulty gauge rheostat would stop the pump from running? The pump is loud, so I'm sure it wasn't running. Or perhaps if it's filter was clogged and that somehow stopped it from running?
@@justcorvettecrazy116 The connections were good and hard to seperate. There was smoke coming out of the rheostat when I used a power probe to put 12 volt s to the level gauge. I'd be a bit worried that the gas tank could explode if it was mostly empty.
Definitely some great information but I will say the amount of times you repeat yourself was starting to bore me. 10-15 minute video, get to the point, more people will watch.
Excellent video and explanation. For the first time ever I understand the start/fuel/relay relationship on my 85.
Thank you for the nice comment.
WOW,what a good video. Lots of information on the L98 fuel system that's not difficult to understand. You are such a detailed and meticulous person, one of the few left. Nice work, Sir.
28 Years as college professor comes in handy. LOL Thanks for the kind comment.
Incorrect explanation. Here is the correct one. The oil switch is not a requirement, it is only a backup for a failed relay. ruclips.net/video/IYgH5lkYoFI/видео.htmlsi=qaM6HO4-uzz9UhyV
Thaks for the info.. My vette has been taking forever before it fires up. Now this will give me options to check, to fix this issue.. Be safe..
Cool, Let me know how it goes.
Purchased a 90 C-4 convertible very low mileage and issues inherited with a car that has associated problems from not driving . Great to see the flow charts " Army style " hoping to to see some solutions . Great site!
Thank you.
A little long, but very well explained in great detail. Thumbs Up
Thank you.
Very well done video. I just subscribed to your channel and will be looking for future videos from you. I am currently experiencing an intermittent fuel delivery problem with my 1990 C4.
Thanks, Let me know if I can help.
You should start a corvette rescue channel. I have a 94 that would fit for the first video. You could be a RUclips star
Thanks Frank, That is the hope. Have a few things planned for the Spring. Always looking for other projects as well.
My vette has little issues that could be remedied but needs a better mech than me. Love the channel and I’ll keep watching and learning
I will check my relay , my starting problem acted like yours .👍👍
Good luck! Report back on what you find.
Thanks bro, very informative 😊
Having just replacing all of my injectors it started about 30 seconds sputters but finally ran very well but noticed when I parked the car I would have to wind the engine for a about 30 seconds again to start the car again other wise the car runs better than it had not knowing actually how good this car runs ! This will be my next step.
Yep sounds like fuel pump relay issue.
Cool Dude, I Liked The Video And Did Give A Thumbs Up.
I Just Fixed My Fuel Issue.
Was The Fuel Pump.
(1991 Corvette Roadster)
Very cool!
Nice video ❤😊
I bought a new relay and it still doesn't want to start. But when I put direct power to the fuel pump. The car will start...but once I remove the direct power from the fuel pump....it shuts off..
Ok that could be tricky. First off double check your fuses for the fuel pump. If fuses are good then most likely a wiring issue. Bad connection somewhere.
Thank you for your video, very helpful
Thanks for the C4 content. Neat old cars but require some care. Subbed.
Thanks Paul.
Perfect... great video! Subbed... now to see if it'll apply to my LT5 ZR-1
You should start a corvette rescue channel.
Thanks Frank, Hoping once my new shop gets built I can take that on.
CHANGED THE RELAY AND THE NEW FUEL PUMP, THE NEW FUEL PUMP DIDN'T WORK. I saw another video with someone adding a C6 fuel pump. This is making me and my mechanic crazy
I know it can be frustrating at times. If there is anything I can do to help, please reach out. i can walk you through some tests.
Great video. I think my 93 relay is bad. I don’t hear the fuel pump priming when the key is in the start position. What are the symptoms of a failed relay? My car will click on the first attempt to start the car. The second attempt cranks the car but will not start. It sucks because my car is stuck in the garage and I need to push it out to get to the fuel pump relay.
Hey thanks for reaching out, the relay only does the priming. If the fuel pump is working when you crank to engine long enough the pump should build pressure and the engine should start without the relay. There are 2 circuits in play here. The real test would be to see if you are getting fuel pressure. A simple test is to shoot some starter fluid into the trottle body and start the car to see if the engine will fire. If the fuel pump is working the car should remain running. You can reach me at: justcorvettecrazy@gmail.com
thanks!
Hey boss so I just replaced the relay and the Fuel gage only builds up pressure when cranking it and then it just lets the pressure go and also when I am on running position fuel pressure does not build up I can’t start by corvette at all do you have any advice??
Thanks for reaching out. You can reach me at justcorvettecrazy@gmail.com. Maybe we can figure it out together. If it is not holding pressure there are a few options we can look at. What year is the car?
If I have power at the connector at the back of the car and no fuel pressure on a gauge on the rail, is it most likely my fuel pump? (new filter and pressure side line has been blown out)
Thanks for reaching out. If you are correctly measuring voltage at the connector at the right time then yes fuel pump could be bad. One sure way to check is to remove the fuel pump and test it outside the car by putting 12V power to the connector to see if it runs.
Another question, I'm working on a '91 convertible. I bought it in Jacksonville without a steering wheel, ECM, throttle body and a couple other things. I replaced all this with a '91 wreck I didn't have insurance that I bought my son and he went through the woods backwards. I replaced all this including the ccm, so it all matches. It was running a little rough, but I had to stop and now I'm back on it after a couple of years. I continued to start it about once a month or so. Now it won't start. I had put a new fuel pump in a while back, now I replaced that one and took the pulser off and replace it with hose. I replaced bladder in the pressure regulator, even thou I had 40 lbs, just didn't know how long it had been there. It's still the same, no start. What confuses me is I press on the valve on the fuel rail and fuel just flows out slowly with the 40 lbs of pressure, thought I remember it spewing out, it's like no pressure on the rail. that's my concern?????
Hey Mitchell,
I am assuming you used a fuel pressure gauge to test the pressure at 40psi at the valve. If so fuel should be there. First thing to do is spray starter fluid into the throttle body. If she starts then you know you have a fuel delivery issue and we can go from there. Try that and get back to me. you can email me direct at justcorvettecrazy@gmail.com
This was the exact issue i had. How did u know about the 4psi of oil pressure thing? Without this video id still be trying to figure it out. Replaced the fuel pump for no reason lol.
Thanks for the nice comment. I read about it, I think maybe in the service manual while looking for a C4 start sequence. Glad the video helped you out.
you have no ecm ? I have a 1991 and I do not have a fuel relay in that spot? May I know what year your car is . thanks
Mine was 1986. ECM is located under the dash on passenger's side. For your car they moved the ECM out to engine bay so your Fuel Pump Relay should be located inside passenger side behind the glove box area. They changed it for 91.
I have an odd problem. I replaced the fuel pump and the relay. Car was running. Sat for about a month and now won't run. I checked the fuse panel out and I'm getting the voltage to the fuel pump fuse location. However with a fuse in it. I get no voltage out of the fuse after I put the fuse in. Do you think my fuel pump regulator may have gone bad because I'm kinda lost as to why I would get the current from the panel but not from the fuse?
Yes the fuse is new also.
Thanks
Thanks for reaching out. What year is the car? It is hard to comment on your voltage when I don't know how you are measuring it. Here is what I would do. Unplug the connector to the fuel pump on top of the tank. Hook up your volt meter there. Then turn the key to the run position and you should get 12Volts for 2 seconds. If you then try to start the car you will get 12Volts while the engine is cranking. If that is the case then the voltage part is fine. See this video at the 13 minute mark.for measuring. ruclips.net/video/JGC1eeOgoYA/видео.html
On one of your videos you mentioned a 90 degree adaptor for your fuel pressure regulator. I've asked the oldest part stores in town and they can't tell me, I've searched ebay and maybe I don't know what the wording is to search for one. Can you tell me where I can buy one?
Hey Mitchell,
It was a 90 degree adapter for the fuel pressure gauge.
Do you have that part number for that relay, I think its easier to get a new one.
There are a couple of options if you look at Rockauto. Verify by your year, I am not 100% sure if the relay changed over the run of the car. I know it did for other relays under the hood. If you want to go OEM I can help you find a number. Let me know if you have any other questions. Cheers.
Looks like this may be my problem. As I've had hard starts when cold. And I don't get fuel pressure with key "on". Though I get fuel pressure when cranking and I get 38psi at idle. I was really dreading having to replace the fuel pump. But I'll put in a new relay and see what that does. As I'm betting it's that as that explains no fuel pressure with key "on", but I get fuel pressure when cranking and at idle, etc.
Sounds like it. Good luck. Feel free to email me justcorvettecrazy@gmail.com if you have any questions.
Hey I have a 92! I have a new opti. New fuel pump relay..not getting spark to the main coil or gas from hoses. Opti not sparking when turned?? Any suggestions please?
Do you have any fuel pressure built up when you turn the key to the run? (not start). Pressure should build for a couple second then hold.
I have a 1987 Corvette. First start of the day has to be with starting fluid. After first start , car runs great all day. Any idea? Thank you
Do you have a fuel pressure gauge? When you turn the key to the run position the fuel pump relay should run the fuel pump for 2 seconds and build up pressure for the start. If that is not happening, check the relay. If you need more info email me at justcorvettecrazy@gmail.com and we can work it out together.
My 1987 Corvette spudders and doesn't have much power during acceleration. I've only experienced a hard start once a few weeks ago. I took the fuel pump relay switch apart the other day and the connection terminals were filled with old black grease. I cleaned the terminals with electrical cleaner spray and put back together. Still the car spudders while running, and I do not hear the fuel pump make any noise during the 1st few seconds of turning key to the on position. Is my issue the relay itself? The car seems like it's running on 7 cylinders instead of 8. I ordered new plugs, wires, cap and rotor. (Haven't recieved them yet.) However I'm thinking the fuel pump relay switch could be the issue with loss of power aswell. Any insight would be appreciated. Thanks!
Fuel pump relay only operates for 2 seconds to prime the fuel rails so it would not be your main problem. After those 2 seconds the ECU takes control of the fuel pump. 1 thing you need to check is your fuel pressure. Loss of power sounds like loss of fuel pressure. If that is the case there are 3 parts to consider, weak fuel pump, plugged fuel filter or leaking fuel regulator.
@@justcorvettecrazy116 thanks for the fast response. You have some very good info on the c4s. The engine does start right away. However the engine spudders and has slow acceleration. Check engine light goes on after a hard acceleration once every few days. Code 32 and 43 are stored in the check engine light. Code 32 is the egr valve I have 1 on the way from ebay for $50. Code 43 is the electronic spark control sensor, I know that most people say change the knock sensor and wiring to it. But is it possible that a fouled spark plug or old spark plug wires could trigger a code 43 and cause loss of power, engine spuddering during acceleration, and a rough idle? The engine has not stalled, just weak power. I'm hoping my issue is a tune up. But with all these relays, sensors, and possible bad fuel pump. I'm not sure and nervous I'm heading down the wrong path. The car has 75,000 miles on it and is an 87 c4. And I just put a new ac delco o2 sensor in 4 days ago. It did nothing to resolve my issue. I will have the tune up parts in a few more days aswell as new egr valve. If these items fail my hopes and dreams of this Corvette coming alive again; I'll be checking fuel pressure and pump immediately after tune up. Thanks!
A good tune-up never hurts and that will eliminate a lot of possibilities. Hit me back an let me know any updates. Good luck!
Hi need some advice about some issues I’m having with my c4 is there a way I can contact u I need expert advice
justcorvettecrazy@gmail.com I will do my best to help if I can.
Great video, my c4 primes to 32lbs. Relay clicks after prime and it goes to 20lbs. Same when I shut of key. Any ideas ?
3 possibilities - 1. faulty check valve in fuel pump 2. leaky/faulty fuel regulator 3. leaky injector. If you want to email: justcorvettecrazy@gmail.com I can help you with some tests.
Thank you so much I will email you because I’m lost lol.
Unfortunately my c4 won’t start!! I changed fuel pump, fuel sending unit, please anyone if you have any ideas please let me know. Been dealing with this since last December.. it turns over but won’t start. Acts like it wanna start but just don’t!! 88 with 71,000 miles
Hey Cory, Thanks for reaching out. If you email me at: justcorvettecrazy@gmail.com I can walk you through some tests. What year is the car?
Hello, i have exactly same symptoms as bad relay has BUT it works. What would be next thing to look at? Cold start takes ages and hot start is almost instat. Idle kinda wandering 7-12k
First thing is to check fuel pressure to see if the pressure is staying when you put the key in run. If the pressure goes up to mid to high 30's and then falls quickly you have a pressure leak. Could be fuel pump check valve or fuel regulator. You can email me at: justcorvettecrazy@gmail.com if you need more advise.
@@justcorvettecrazy116 yes i will thanks a lot. Keep up the good work man
Found the problem, while i was working on ccv valve leaking hose i broke 9th injector wire. Fixed that and car fires up nice hot n cold.
@@usec5503 Good catch!
Please repost this I’ve did everything until I watched this video it helped than you fir you time
Glad the video helped you out.
I just got my new to me 1986 C4 (47,000 original miles) going this morning. It hadn't run in 7-8 years and various people appear to have worked on it's issues. I followed the procdures shown in this video and quickly determined a bad fuel pump. When I removed the fuel pump from the tank and applied 12 volts to what I thought was the motor the fuel gauge resistor smoked (a lot). I disconnected the electric wire from the rheostat and then put power to the pump and it worked. I took the car for a drive. I'm not sure what exactly happened. Anybody got any thoughts on why the faulty gauge rheostat would stop the pump from running? The pump is loud, so I'm sure it wasn't running. Or perhaps if it's filter was clogged and that somehow stopped it from running?
Could have been a bad connection at the pump?
@@justcorvettecrazy116 The connections were good and hard to seperate. There was smoke coming out of the rheostat when I used a power probe to put 12 volt
s to the level gauge. I'd be a bit worried that the gas tank could explode if it was mostly empty.
All of my relay at this part number 14089936, its hard to find these in stock, any suggestions?
Fuel pump relay is not where you said it was for a 92 Chevy corvette
Different Engine package.
I can't wait for my car to start like that.\
Definitely some great information but I will say the amount of times you repeat yourself was starting to bore me. 10-15 minute video, get to the point, more people will watch.
Thanks, I guess 26 years as a teacher ... hard to stop. LOL
I'm not having a fuel pressure problem
Ok, What is your problem?