Garys Dream

I'm having a problem with my 92 LT1. When I try to start the engine, it fires off briefly, but dies right away. To begin with when this would happen, I would turn the key all the way off, wait a minute and try it again. Sometimes it would start and sometimes not. Now, it will not stay running at all. Any suggestions??? HELP!!!

tjwong

Do you have a fuel pressure gauge to confirm the loss of fuel pressure. There are other things that can cause a no start problem. You can get a inexpensive fuel pressure gauge from Auto Zone or most any auto parts house. Connect the hose to the test port on the fuel rail, upon power up when you turn the ignition on you should see about 43 PSI of pressure. If the fuel rail isn't charged up, it may take a couple key cycles. Or just turn the engine over, at that moment the fuel pump will be running and you should see pressure. If not you probably have a faulty fuel pump or no power to the pump.

rick lambert

when was the last time you changed fuel filter/fuel pump?

Garys Dream

Hi Rick and thanks for your input. I've never changed the fuel filter or pump. And I've had the car for 7 years... Maybe it's due??? But for some reason, I feel like it might be some kind of a relay/elec problem because when the problem first started, I would try to start the car and it would fire briefly and quit. Then, I would cycle the key all the way off, wait a few seconds, and then back on, and the car would start and run just fine. If it were the fuel filter or pump, I would think that it would act starved for fuel even after I got it running and driving around. What do you think?

Frizlefrak

Or a bad fuel pressure regulator. If you have no or little pressure, pinch off the return line with some vice grips and see if the pressure increases. If it does, but falls when you remove the vice grips, it's the regulator. If not, it's either the pump or a restriction in the pressure line somewhere.

Garys Dream

COOL... Thanks so much... I will give it a try and see what happens... That sounds like it might work...

LaVidaLoca

Hmmm. May have to go back and read the manual, but I seem to recall that the fuel pump voltage passes through an oil pressure sensor that is bypassed at initial start-up. So you could start it but it would not continue to run if there was no oil pressure (or a bad sensor). Not sure on your engine, but on my 85 the sensor is right behind the distributor. I still think getting a fuel pressure guage on it as stated above is the best starting point. However you might check the oil and oil pressure also.

If it ends up being the fuel pump it is fairly simple to replace (unlike many Corvette parts). First check on the fuel pump is to stand at the rear of the car and have someone turn on the ignition but not crank the engine. You should hear the pump cycle on for about 10 sec. If you do not hear it, the pump is likely bad. If you do hear it, that does not mean it is OK. I have seen pumps only put out 10lbs of pressure and the car just won't run on that. Back to the pressure guage to see what the pump is doing.

rick lambert

That's waaaaaaaay to long on the fuel filter-and may be the problem-or at least a contributing factor.Regarding the above post, when you first turn your key on, the FP relay will run for a few seconds-you can hear it, if not replace it. Second if the relay is shot, you need to crank the engine until it reaches 4 lbs of oil pressure.My 87 acted somewhat like yours-I ended up replacing the relay, pump and sock-end of problem. Good luck.BTW, when I replaced the relay I noticed the insulation on the wiring had schrunk back an inch or so-causing bare wire contact, which I fixed-our C4s-especially earlier ones like mine are notorious for this.

mitchcole

Togo

the LT1 has a TPS doesn't it? may want to check the voltage - don't ask me how, i have no idea!

i would change the fuel filter FIRST - i just did this on mine, and next is the fuel pump and all 8 injectors - my car had what i think were the ORIGINAL spark plugs and wires - so i can imagine nothing else was done maintenance wise on this car!

rubydog

See Rubydog thread posted couple days ago. My 93 fires up then immediately dies. But I have "sys" flashing in odometer area and security flashing and I have codes when I run CCM test. (Not the ECM test which tests OK.) Based on my Service manual, these CCM codes mean that the serial link is down between ECM and CCM. When that link is down, the FEDS fuel enable is not sent to ECM so it fails to turn on injectors after the initial burst.

So, see if you have "sys" flashing. If you do, we are in same boat. Even though I have pressure on fuel rail, I get a no start. I'm debating on what to do.

Options include replace ECM (that can cause this problem), dig in and find the CCM (hard job), or try to check the serial link wires for continuity and no shorts to ground. The ECM replacement is easiest, but my luck, it will be something else!

Please get back to me since my ruby is dead in the water!

Buck from Virginia