Out for a Sunday drive in the heat today in my '87. Ran fine until I shut it off. After starting it again, it idled rough for a second, shut down, and then wouldn't restart. It would crank, sputtered, and die.
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After sitting for 2 hours or so, it fires right off like nothing ever happened. Acted just like an old carbed engine that would vapor lock.

Anyway, no OBD 1 codes showing. New fuel filter last year. I didn't check fuel pressure. Nothing else obvious on quick glance.

Any thoughts on possibilities?

 

Had similar symptoms, the wiring on the fuel pump sender was fried. It'd make connection and then suddenly wouldnt.

I'd start with the usual diagnostics of the fuel pump, relay, and then look at the sender unit.

 

Next time check for spark, fuel pressure, and injector pulse.

 

Thanks guys. Those are good ideas for where to start. Just one more thing to add, I just took it out for a 20 mile or so drive. It is running, but now seems to want to fall flat/bog around 2200-2300 RPM, especially under part throttle. Doesn't seem as bad under full throttle.

I don't have time to do any additional diagnostics today. But, will report back what I find when I do.

 

My friends tojan does. Runs, you shut it off and go to start it after it sits a few it cranks and cranks then sputters and runs like crap for a few seconds and then eventually clears. I had a gauge on it and it made fuel pressure the whole time like it was supposed to. The fix for his was just cycle the key twice before starting and that would purge the line out and be okay. Never could figure out wjat was up with that. New regulator, New pump, New injectors. Still does it to this day. Sounds very different than your issue however.

 

Couple if quick tests this evening. Measured the resistance across all of the injectors. They all came back in the 16.2-16.6 range. (See pic) I didn't get a chance to run a pulse test yet. Will do that tomorrow.

Also attached pics of the fuel pressure test. Approx 24 psi with ignition on and 35 psi running.

 

Found the diagnostic procedure in the service manual. Looks like they use 40.5 PSI as their reference point.




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Quick video of the fuel pressure test. I'm a little perplexed by the fluttering of both the gauge and the engine at this point.

 

Looks like you need a fuel pump ck the lines to make sure they arent cracked when you pull it out.
Comes out top of fuel tank easy repair
When you shut it off does the fuel bleed off quickly?

 

I have not had a Vapor lock on my L98 equipped Corvette. I totally agree with Vader86 about going through the fuel system to verify that when you start at the battery and follow the power. Occasionally I will cheat and just apply battery voltage to the fuel pump at it's harness and then follow it from there. This way if I have a bad fuel pump which is highly likely you find it right away. There are three wires coming out of the Fuel Pump Assembly. The Big one is the Power and the Middle one is the fuel level gauge return wire and the third wire is the Ground.

Getting to the fuel tank requires removing the panel over the fuel tank filler area. Under the cover and other parts you will see the plate attached to the fuel tank that has the Fuel Pump Assembly attached to it. The little bolts are not frequently the easiest to remove. They will break very easily and that is not good. I suggest soaking them with a good penetrating oil. Then gently try each bolt and break them free without breaking them off. When you remove the Fuel Pump Assembly it comes with the fuel tank level sending unit as well. Take your time and remember how it comes out, take pictures if needed to remember. The Fuel Pump is mounted on the bracket and should have a fuel intake sock on it.

Once it is removed from the fuel tank you can unhook the wiring harness and again take a picture if you have to. Remove the fuel pump and replace it with the new one. From the factory there is a device known as a "Pulsator" and it was in between the fuel pump and the Fuel line. The Pulsator is no longer really needed so we remove it and replace it with a short section of Fuel Injection Fuel Hose designed for submersion in Fuel. This go's from the fuel pump to the bracket upon which you put another new fuel injection Fuel Hose Clamp over it and secure it. Then you reattach the wires and re-assemble the fuel tank and put the Cover back on. The cover has 8 or 10 bolts holding it to the fuel tank, When re-installing them I applied a little anti-seize.

The "Pulsator" was designed (from what I read) to smooth-en out the flow of fuel in the fuel lines. To rid the system of the "Fuel Pulses". When my fuel pump is pumping the fluid comes out nice and smoothly so I guess it solved itself.

 

Yes, it does bleed off over a period of time. Thanks for all of the assistance everyone. Looks like I'm going to be trowing a fuel pump at it this weekend. I just ordered a Delphi. Should be here by Friday.

 

Don't forget to get asmall section of F.I. rated Fuel hose to replace the Pulsator and some new "Fuel Injected" clamps. If the Pulsator has been replaced then replace the hose used in its place.

 

Thanks. I will.

 

New Delphi pump in. Good steady fuel pressure. Started right up and runs smooth.