Corvette - Engine Troubleshooting


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Auto Repair Home>> Automotive Repair>> Engine Troubleshooting

zeeke
New User

Sep 5, 2014, 7:13 PM

Post #1 of 3 (1181 views)

Corvette	Sign In

1991 corvette 5.7 shuts down under load will restart later but runs very rough then finally smooth

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 5, 2014, 7:35 PM

Post #2 of 3 (1171 views)

Re: Corvette	Sign In

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.

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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 6, 2014, 7:01 AM

Post #3 of 3 (1158 views)

Re: Corvette	Sign In

Do the tests Hammer Time listed out for what is missing. I think you'll find lack of spark as only a guess till you know for sure as this distributor, coil in the cap and module inside distributor plain connections to all that stuff has to be good all the time. Under load it is stressed more than at idle.

Running rough for a bit when starting later is no surprise as that clears out so not a clue by itself as then it's running fine.

Find what drops out and if spark check everything to do with that type distributor,

T

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