fishdude7

The car is a 2000 Corvette 6 speed. I don’t have any current codes.

I apologize in advance if this is a long post. I just want to accurately inform everyone on my problem and what I have already done to try to resolve it.

Around three weeks ago I was left stranded after getting my air conditioning recharged for the summer heat. The car would start, and immediately die. I noticed that I could not hear the fuel pump turn on to build pressure in the fuel rails. I hooked up a fuel pressure gauge and the car only had 12psi when cranking. I know that it should be way higher at 58psi. I replaced the fuel filter/regulator with a GM unit two months ago. The owner of the shop where the A/C was being charged said to replace the pump and call it a day. The car has 150,000 miles on it and the pump was never replaced. So I replaced the pump, and five hundred dollars later the car would still not run. The fuel pump would not turn on.

I have had problems in the past with chipmunks eating through wires on cars in the driveway. I thought that the gray fuel pump power wire was broken somewhere from the fuse panel to the fuel pump. Next, I hooked up a homerun from the battery to the fuel pump and the car ran and idled. I drove the car home and everything was fine. I then looked at all the posts on the forum that I could find relating to fuel pumps, relays, and fuses. I read that if pin 30 and 87 were jumped that it would bypass the fuel pump relay. I did this and the car ran and idled fine, so I know that the gray power wire to the fuel pump is fine.

I wound up replacing the relay and the car ran fine for two days and left me stranded again.

I also saw that some forum members had similar problems that were resolved when the grounds were taken apart and cleaned. Sp122 and g105 are the main grounds that members said to check, so I cleaned them again and added dialectic grease. I have had problems in the past with reduced power mode. I have personally cleaned and sealed every ground and splice pack on the chassis and engine within the past year. Just to make sure I inspected them all again.


Screen shot from the forum.

Again I replaced the relay with one from GM. The engine would not run, and the relay would not close to complete the circuit. I pulled out a test light to check the pins on the fuse panel. Below is what I found.
A. Pin 30 – Ground
B. Pin 85 – Positive with key on
C. Pin 86 – Positive with key on for 2 seconds then turns off
D. Pin 87 – Positive with key on

Today, I decided to remove the battery and battery tray in order to examine the wires underneath it. I examined the male pins and female pins on sp122. They were clean, so I put everything back together. To my surprise the car started and idled fine. The relay now clicks and closes to complete the circuit.
A. Pin 30 – Ground
B. Pin 85 – Is no longer positive with the key on and is now a ground
C. Pin 86 – Positive with key on for 2 seconds then turns off
D. Pin 87 – Positive with key on

Fortunately, I also have a 2002 Z06, so I tested the pins on the fuse panel and pin 85 is also a ground. I am nervous about driving the convertible and getting stranded again. I am not sure what I did besides disconnecting the battery in order to correct pin 85.

My questions are:
A. Why is pin 85 now no longer positive with the key on? I only disconnected the battery to examine splice pack sp122 which was nice and clean.
B. What is pin 85 and where does that wire under the fuse panel go?
C. Is there a problem with the PCM? Did it restart after disconnecting the battery?
D. How exactly does the power feed though the relay in order for it to engage?

I would appreciate any expertise helping me to remedy this problem. I was all ready to give up and bring it to the dealership today but it is now running fine, so I would get charged and not really know if they figured out what the heck is actually happening. Thanks, Scott.

neutron82

since you replaced the relay and it is now working intermittently I'm wondering if the terminals in the fuse box have opened up and are not making good contact with the relay pins... you can try taking an old relay apart and using one of the pins to see if any of the fuse box terminals are loose... once you have the relay dismantled insert the pin into each of the fuel pump relay slots on the fuse box and you should feel a decent amount of resistance, if the pin slides into any of the terminals with no resistance then the terminal has probably opened up and no longer making good contact... if this is the case you can either use a dab of solder on the relay pins to make it a little thicker so it will make better contact in the fuse box terminals, you could attempt to open up and repair the fuse box which might be a nightmare of it's own, or replace the fuse box with a known good one... I would prefer to repair or replace it personally, I'm not a fan of using the solder trick for a permanent fix because you are essentially just opening the terminal even more than it already is (basically making the problem worse)

fishdude7

I just tried using what was suggested, but the pins are pretty tight and making good contact. I don't believe that this is the problem.
When the car wouldn't start and idle pin 85 with the key on was positive. After the battery was disconnected it turned to a ground allowing the relay to close and the car to run. What would cause this to happen? Right now, I can't drive the car far in case it happens again.

4horseman

I am having same issue. Did you figure what the problem was?

fishdude7

I went through and re-cleaned all the body and engine grounds. There's a thread on electrical grounds on the forum showing the location of each. I don't know which ground cured the issue for me, but it has been running great since. Be sure to use dielectric grease on the studs and nuts to to prevent this from happening again. I know that this issue was very frustrating for me, I hope that this works for you too.

Scotty