1990 corvette problem
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Joined: Oct 2025
Posts: 57
Likes: 2
From: des moines
1990 corvette problem
Hey guys, I’ve got a 1990 Corvette C4 and I recently replaced the passenger-side exhaust manifold. After the install, I took it for a drive and noticed my voltage dropped to 0. The car started back up for a few moments but then died again, so I had to tow it home.
It’ll start if I spray starter fluid, but it won’t stay running. I let it sit for a couple of days, and now it only cranks over once before stopping. The battery is fully charged and the starter works fine.
Has anyone run into something like this before or know what could be causing it?
It’ll start if I spray starter fluid, but it won’t stay running. I let it sit for a couple of days, and now it only cranks over once before stopping. The battery is fully charged and the starter works fine.
Has anyone run into something like this before or know what could be causing it?
Last edited by c4_kesler; Oct 7, 2025 at 11:52 AM. Reason: wrong wording
Melting Slicks
Joined: Feb 2003
Posts: 2,661
Likes: 806
From: Saskatoon Sask.
hey guys i was driving my 1990 corvette c4 and i had just replace the manifold on the passenger side i was driving and i seen my volts drop to 0 it started back up but only for a few moments had to tow my car home itll start up with starter fluid, that night about 2 days ago i let it sit for awhile and i come back and the car cranks over but only once i had my battery charged and my starter works anybody know how to hel me out?
Racer
Joined: Sep 2021
Posts: 360
Likes: 59
you need a voltmeter to monitor the voltage during crank or just look at the gauge in the dash. If the voltage drops below around 8V it won't crank anymore. If this is the case then either the battery is degraded or not charged or the connections are bad. If the connections are bad it can be either the terminals not tighten properly or a broken cable. But it seems the interuption affects all systems not the starter only. If you worked at the headers seems more likely you disconnected the battery then you didnt tighten the terminals properly
It happened to me twice., It would not crank at all, but had enough power some electrical systems including dash
PS while I was writing I see you got it fixed, what was it?
It happened to me twice., It would not crank at all, but had enough power some electrical systems including dash
PS while I was writing I see you got it fixed, what was it?
Thread Starter
Advanced
Joined: Oct 2025
Posts: 57
Likes: 2
From: des moines
you need a voltmeter to monitor the voltage during crank or just look at the gauge in the dash. If the voltage drops below around 8V it won't crank anymore. If this is the case then either the battery is degraded or not charged or the connections are bad. If the connections are bad it can be either the terminals not tighten properly or a broken cable. But it seems the interuption affects all systems not the starter only. If you worked at the headers seems more likely you disconnected the battery then you didnt tighten the terminals properly
It happened to me twice., It would not crank at all, but had enough power some electrical systems including dash
PS while I was writing I see you got it fixed, what was it?
It happened to me twice., It would not crank at all, but had enough power some electrical systems including dash
PS while I was writing I see you got it fixed, what was it?
well i didn't get it fixed but some guy said my wording was confusing
Thread Starter
Advanced
Joined: Oct 2025
Posts: 57
Likes: 2
From: des moines
you need a voltmeter to monitor the voltage during crank or just look at the gauge in the dash. If the voltage drops below around 8V it won't crank anymore. If this is the case then either the battery is degraded or not charged or the connections are bad. If the connections are bad it can be either the terminals not tighten properly or a broken cable. But it seems the interuption affects all systems not the starter only. If you worked at the headers seems more likely you disconnected the battery then you didnt tighten the terminals properly
It happened to me twice., It would not crank at all, but had enough power some electrical systems including dash
PS while I was writing I see you got it fixed, what was it?
It happened to me twice., It would not crank at all, but had enough power some electrical systems including dash
PS while I was writing I see you got it fixed, what was it?
i will try this the battery is brand new but i will let you guys know
Drifting
Joined: Feb 2008
Posts: 1,537
Likes: 177
From: NE Ohio
2024 C4 of the Year Finalist - Unmodified
Hey guys, I’ve got a 1990 Corvette C4 and I recently replaced the passenger-side exhaust manifold. After the install, I took it for a drive and noticed my voltage dropped to 0. The car started back up for a few moments but then died again, so I had to tow it home.
It’ll start if I spray starter fluid, but it won’t stay running. I let it sit for a couple of days, and now it only cranks over once before stopping. The battery is fully charged and the starter works fine.
Has anyone run into something like this before or know what could be causing it?
It’ll start if I spray starter fluid, but it won’t stay running. I let it sit for a couple of days, and now it only cranks over once before stopping. The battery is fully charged and the starter works fine.
Has anyone run into something like this before or know what could be causing it?
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Melting Slicks
Joined: Feb 2003
Posts: 2,661
Likes: 806
From: Saskatoon Sask.
Drifting
Joined: Feb 2008
Posts: 1,537
Likes: 177
From: NE Ohio
2024 C4 of the Year Finalist - Unmodified
That is still a fuel problem. He needs to test fuel pressure and injectors input. If there is voltage at injectors is is gas supply. Clogged injectors, fuel filter, etc. Test do not throw parts at it. Get a volt meter and fuel pressure tester an get in to the problem area.
Start with fuel pressure. If that’s fine, get a noid light and test for injector pulse.
Thread Starter
Advanced
Joined: Oct 2025
Posts: 57
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From: des moines
That is still a fuel problem. He needs to test fuel pressure and injectors input. If there is voltage at injectors is is gas supply. Clogged injectors, fuel filter, etc. Test do not throw parts at it. Get a volt meter and fuel pressure tester an get in to the problem area.
Melting Slicks
Joined: Feb 2003
Posts: 2,661
Likes: 806
From: Saskatoon Sask.
That is still a fuel problem. He needs to test fuel pressure and injectors input. If there is voltage at injectors is is gas supply. Clogged injectors, fuel filter, etc. Test do not throw parts at it. Get a volt meter and fuel pressure tester an get in to the problem area.
Safety Car
Joined: May 2001
Posts: 4,741
Likes: 1,639
From: Fairfax Virginia
I had an issue with my L98 in our 1988 C4 with the engine not running and issues similar to yours. It was a fairly easy fix, once I identified what the problem was.
What voltage do you see at the fuses? I would measure the voltage of the battery, at the battery and then start measuring through the fuse block. I found less than 10 volts on some of the fuses coming into the panel. I checked the radio and it had low voltage as well. With this situation I noticed that my fuel pump was not working, likely to low power as well.
Using a Power Probe I then took battery power to the fuel pump harness near the pump and checked it with a full 12 volts and the pump ran fine. The voltage getting to the pump was the problem. I traced it back to the fuel pump relay and replaced it as well. The low voltage was the cause for the pump fault. With full power it worked great. After realizing that the fuses were not getting full voltage, I followed the power and it went to a small post on the drivers side compartment near the battery. This post has a large wire that went from the post to the battery positive terminal and supplied the post with full battery power. The post on my C4 was covered in corrosion and this was what caused my low voltage situation. After removing the 7 fusible links and their ring terminals I cleaned each one down to bare metal and then cleaned the post as well. This post essentially powers the entire car by feeding the power into the fuse blocks. The corrosion had created a huge resistance to the power flowing through this connection. After cleaning and re-assembling with Conductive BATTERY Grease and re-attaching to the post, the battery voltage was spot on inside the car and out. The fuel pump ran full speed and the car was working again.
What is the battery voltage of the car sitting? How about when running? Are the headlights as bright as they need to be? Low voltage can make them produce less light. Fuel pumps will not make pressure without the right voltage going into them...
Best regards,
Chris
What voltage do you see at the fuses? I would measure the voltage of the battery, at the battery and then start measuring through the fuse block. I found less than 10 volts on some of the fuses coming into the panel. I checked the radio and it had low voltage as well. With this situation I noticed that my fuel pump was not working, likely to low power as well.
Using a Power Probe I then took battery power to the fuel pump harness near the pump and checked it with a full 12 volts and the pump ran fine. The voltage getting to the pump was the problem. I traced it back to the fuel pump relay and replaced it as well. The low voltage was the cause for the pump fault. With full power it worked great. After realizing that the fuses were not getting full voltage, I followed the power and it went to a small post on the drivers side compartment near the battery. This post has a large wire that went from the post to the battery positive terminal and supplied the post with full battery power. The post on my C4 was covered in corrosion and this was what caused my low voltage situation. After removing the 7 fusible links and their ring terminals I cleaned each one down to bare metal and then cleaned the post as well. This post essentially powers the entire car by feeding the power into the fuse blocks. The corrosion had created a huge resistance to the power flowing through this connection. After cleaning and re-assembling with Conductive BATTERY Grease and re-attaching to the post, the battery voltage was spot on inside the car and out. The fuel pump ran full speed and the car was working again.
What is the battery voltage of the car sitting? How about when running? Are the headlights as bright as they need to be? Low voltage can make them produce less light. Fuel pumps will not make pressure without the right voltage going into them...
Best regards,
Chris
Thread Starter
Advanced
Joined: Oct 2025
Posts: 57
Likes: 2
From: des moines
I had an issue with my L98 in our 1988 C4 with the engine not running and issues similar to yours. It was a fairly easy fix, once I identified what the problem was.
What voltage do you see at the fuses? I would measure the voltage of the battery, at the battery and then start measuring through the fuse block. I found less than 10 volts on some of the fuses coming into the panel. I checked the radio and it had low voltage as well. With this situation I noticed that my fuel pump was not working, likely to low power as well.
Using a Power Probe I then took battery power to the fuel pump harness near the pump and checked it with a full 12 volts and the pump ran fine. The voltage getting to the pump was the problem. I traced it back to the fuel pump relay and replaced it as well. The low voltage was the cause for the pump fault. With full power it worked great. After realizing that the fuses were not getting full voltage, I followed the power and it went to a small post on the drivers side compartment near the battery. This post has a large wire that went from the post to the battery positive terminal and supplied the post with full battery power. The post on my C4 was covered in corrosion and this was what caused my low voltage situation. After removing the 7 fusible links and their ring terminals I cleaned each one down to bare metal and then cleaned the post as well. This post essentially powers the entire car by feeding the power into the fuse blocks. The corrosion had created a huge resistance to the power flowing through this connection. After cleaning and re-assembling with Conductive BATTERY Grease and re-attaching to the post, the battery voltage was spot on inside the car and out. The fuel pump ran full speed and the car was working again.
What is the battery voltage of the car sitting? How about when running? Are the headlights as bright as they need to be? Low voltage can make them produce less light. Fuel pumps will not make pressure without the right voltage going into them...
Best regards,
Chris
What voltage do you see at the fuses? I would measure the voltage of the battery, at the battery and then start measuring through the fuse block. I found less than 10 volts on some of the fuses coming into the panel. I checked the radio and it had low voltage as well. With this situation I noticed that my fuel pump was not working, likely to low power as well.
Using a Power Probe I then took battery power to the fuel pump harness near the pump and checked it with a full 12 volts and the pump ran fine. The voltage getting to the pump was the problem. I traced it back to the fuel pump relay and replaced it as well. The low voltage was the cause for the pump fault. With full power it worked great. After realizing that the fuses were not getting full voltage, I followed the power and it went to a small post on the drivers side compartment near the battery. This post has a large wire that went from the post to the battery positive terminal and supplied the post with full battery power. The post on my C4 was covered in corrosion and this was what caused my low voltage situation. After removing the 7 fusible links and their ring terminals I cleaned each one down to bare metal and then cleaned the post as well. This post essentially powers the entire car by feeding the power into the fuse blocks. The corrosion had created a huge resistance to the power flowing through this connection. After cleaning and re-assembling with Conductive BATTERY Grease and re-attaching to the post, the battery voltage was spot on inside the car and out. The fuel pump ran full speed and the car was working again.
What is the battery voltage of the car sitting? How about when running? Are the headlights as bright as they need to be? Low voltage can make them produce less light. Fuel pumps will not make pressure without the right voltage going into them...
Best regards,
Chris
Drifting
Joined: Feb 2008
Posts: 1,537
Likes: 177
From: NE Ohio
2024 C4 of the Year Finalist - Unmodified
Melting Slicks
Joined: Feb 2003
Posts: 2,661
Likes: 806
From: Saskatoon Sask.
Drifting
Joined: Feb 2008
Posts: 1,537
Likes: 177
From: NE Ohio
2024 C4 of the Year Finalist - Unmodified
Well it is better to know the problem area. If you if you prime and it starts and stalls in short time it not a electrical problem or it would not start primed. Thus it has to be a relay or wiring problem. so you know what to chase down.
Sorry if I confused you