So to start off I have a 1989 corvette and over the past 2 months it has been having very intermittent fuel pump issues. Normally after I park the car and go to start it a little bit later the fuel pump is not getting power and will not turn on and for the car not to start except for a couple seconds to use what is already in the line. It won’t even turn on for the 2 seconds to prime the system. I’ve messed with the relays and they are functioning perfectly fine and I’ve even swapped it while the issue was going on with no fix trying multiple different relays.

Usually to fix the problem I can wait a little bit (maybe an hour or 2) and it will start perfectly fine. The only other option I’ve found recently that works is if I cycle the key about 10 times on and off waiting roughly 1 minute in between it will start perfectly fine.

Every time until today this has happened after parking the car and trying to get in and drive off later. Today however, as I was driving down the road the fuel pump died and I had to pull off to the side of the road. Did the simple checks of turning the key and the fuel pump would not turn on to prime the system. Cycled the key as stated above and it started back up and did fine.

So usually the time between this happening is about 1-2 weeks. So not very often. However I am just now getting around to have time to deal with this and really wanted the forums opinion on what’s going on and what to check. I am feeling it is a wiring or faulty pump issue but would like some guidance on what to check before just throwing parts at it.

Any help is appreciated and let me know if you need any other information.

 

So you stated the fuel pump is not getting power. Did you mean the fuel pump is not running ? Or you mean you tested for power at the pump and there is no voltage to the pump...

 

On my '93 I was getting erratic fuel pressure as the pressure gauge had about a 10 lb fluctuation. Did it when the engine was warm. When I pulled the pump the outside foam had shriveled up and pump was probably overheating and going south. Had two new Racetronix pumps and kits on hand that included heavier wiring for inside the tank. I used the smaller 190l pump instead of the 255l. Smothed out my pressure with no fluctuations.

 

Same issue for me, bypassed Racetronix system and wired to factory, and the voltage is somehow being killed off to the pump or the pump itself is dying intermittently.

If it wont prime you must apply +12 to terminal G of the ALDL port, if it does not prime then, then you must check voltage getting to the pump by removing the trim pieces and checking manually with a DVM. If voltage is there, then its something wrong with the pump or the wiring to the pump.

 

Sorry I guess I should have clarified that the pump is not running. silly me haha

See the only problem is its so intermittent im not normally some where that I can do much diagnosing. Looks as if it'll be a hunting game on trying to trouble shoot this.


I'm gonna pull it all apart in a day or 2 and check all the wiring for simple things such as shorts, burning, and resistance while moving it around a bit. Along with maybe pulling the pump and inspecting it.

 

Yes, I understand the frustration. Mine works fine and then it doesnt, and you have to troubleshoot when it doesn't. Car has stranded me twice as a result, and no tools or a way to work at either time.

I think you better just plan on troubleshooting the very next time you go out and it won't prime. That is what I do.

My suspicion is the ground for the pump, not the rest of the circuit.

 

Yeah check all the connections carefully. Sounds like one of the connectors is going to be all blackened and not making proper contact. If all the connections are clean and tight then suspect a failing pump.

 

Yep, thats the plans for now. Carry me a pice of wire to jump to the aldl and keep a multimeter with me to find out where and what is going on.

Thats what im hoping for. Maybe something will stick out and be really noticeable once I get it apart. Worst case scenario I do think this is the original pump and if not is still 10+ years old and probably tired anyway.

 

There's been no mention of the FP fuse. Be sure the pins are clean, and that it's plugged in securely. Do you have voltage at the fuse during the 2 sec. "prime time"? If so, putting 12 v. on ALDL pin G won't do anything for you. If you have 12 v. at the fuse during the "prime time", and no FP, you've either got a bad ground, or a bad pump.

I hope you have the FSM.

 

Oh trust me FSM is always available. One of my best investments.

Im gonna go check and clean the fuse, if needed, now since that is a quick and easy thing to do.

 

when I first bought my 89 it ran for 3 days and just stopped running at all. had a friend mechanic look over everything, air fuel, electrical. He is really good and was getting frustrated. He went to gas refill box pulled it out to see if the fuel pump was easy to get to without dropping the tank but in that process he found a ground wire there all corroded. cleaned it up and the surface. Car started right away and has run since
Good Luck

 

Hi Red89, Can you tell me where the FP relay is located? I've been reading this forum for hrs and only found 1 thread where they claim its located between the 2 MAF relays behind the batt. and the brake booster. My 89 car does not have a relay there but has something that looks like a solenoid the size of a relay to the right of the 2 relays behind the Batt. Also I can't find the FP fuse, its not in the FPanel… Thanks Dave...

 

Fuel pump relay is next to the wiper motor on the firewall