engine dies when let off gas pedal while starting
Thread Starter
Intermediate
Joined: Aug 2014
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engine dies when let off gas pedal while starting
hey guys
my c3 corvette will only start briefly and only if i'm pumping the gas pedal constantly. the minute i let off the gas pedal, it will immediately die. i just a did a bunch of stuff to it, im thinking maybe it is related
Here's what i did:
replaced spark plugs
ran compression test on cylinders (had to unplug and plug in distributor)
removed and replaced air filter (to run compression test with throttle open)
while doing compression test, i accidentally knocked off a wire running form alternator to engine block, so i reconnected it. (not sure what that wire does?)
replaced valve cover gaskets
I'm not sure if any of this could have been the culprit, but I'm guessing so. Any advice?
thanks!
my c3 corvette will only start briefly and only if i'm pumping the gas pedal constantly. the minute i let off the gas pedal, it will immediately die. i just a did a bunch of stuff to it, im thinking maybe it is related
Here's what i did:
replaced spark plugs
ran compression test on cylinders (had to unplug and plug in distributor)
removed and replaced air filter (to run compression test with throttle open)
while doing compression test, i accidentally knocked off a wire running form alternator to engine block, so i reconnected it. (not sure what that wire does?)
replaced valve cover gaskets
I'm not sure if any of this could have been the culprit, but I'm guessing so. Any advice?
thanks!
Le Mans Master
Joined: Jul 2006
Posts: 8,117
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From: charlotte north carolina
I'm not sure which wire was displaced, but if you reconnected it properly, it wouldn't cause any problems. I think that you have crossed one or more spark plug wires, and have the firing order out of sequence. It should be 1 8 4 3 6 5 7 2. Also make sure you have the air filter base on correctly so that the choke mechanism operates freely.
I re-read your post. What do you mean "unplug" the distributor? Did you remove it from the engine, or just disconnect the wires? If it was removed, it may have not been installed in the correct position.
I re-read your post. What do you mean "unplug" the distributor? Did you remove it from the engine, or just disconnect the wires? If it was removed, it may have not been installed in the correct position.
Last edited by jnb5101; Jun 24, 2015 at 09:05 AM.
Race Director
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From: Wellington, FL
St. Jude Donor '11 thru '25
Check your plug wires for proper firing order unless the car was running fine before you replaced the plugs and you replaced the plugs disconnecting and reconnecting each wire on its respective plug before moving on to the next one.
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Race Director
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you state doing the compression test you had to unplug and plug in the distributor, that is what others are asking you about. What wire or wires exactly did you unplug and plug?
Did you gap the spark plugs and tighten them correctly?
Did you gap the spark plugs and tighten them correctly?
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I wasn't able to get a torque wrench to fit to properly torque several of the spark plugs. The exhaust manifold was in the way. I turned them 1/4-1/2 turn past hand tight. I didn't gap the spark plug, i thought they were pre-gapped?
Race Director
Joined: Sep 2001
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From: Wellington, FL
St. Jude Donor '11 thru '25
There were three wires connected to dist (BAT, GRD, TACH) and in unplugged all three, then reconnected them.
I wasn't able to get a torque wrench to fit to properly torque several of the spark plugs. The exhaust manifold was in the way. I turned them 1/4-1/2 turn past hand tight. I didn't gap the spark plug, i thought they were pre-gapped?
I wasn't able to get a torque wrench to fit to properly torque several of the spark plugs. The exhaust manifold was in the way. I turned them 1/4-1/2 turn past hand tight. I didn't gap the spark plug, i thought they were pre-gapped?
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Spark Plugs
There were three wires connected to dist (BAT, GRD, TACH) and in unplugged all three, then reconnected them.
I wasn't able to get a torque wrench to fit to properly torque several of the spark plugs. The exhaust manifold was in the way. I turned them 1/4-1/2 turn past hand tight. I didn't gap the spark plug, i thought they were pre-gapped?
I wasn't able to get a torque wrench to fit to properly torque several of the spark plugs. The exhaust manifold was in the way. I turned them 1/4-1/2 turn past hand tight. I didn't gap the spark plug, i thought they were pre-gapped?
So lets start with exactly what brand and part number plug did you install?
What year and engine do you have and any modifications?
Regardless of what they are, they should be checked for the correct gap.
They maybe loose. You tighten them using a 3/8 drive ratchet and just use your forearm strength to tighten them once they are fully seated.
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It sounds like you havent done this too often, based on not gapping the plugs and trying to use a torque wrench.
So lets start with exactly what brand and part number plug did you install?
What year and engine do you have and any modifications?
Regardless of what they are, they should be checked for the correct gap.
They maybe loose. You tighten them using a 3/8 drive ratchet and just use your forearm strength to tighten them once they are fully seated.
So lets start with exactly what brand and part number plug did you install?
What year and engine do you have and any modifications?
Regardless of what they are, they should be checked for the correct gap.
They maybe loose. You tighten them using a 3/8 drive ratchet and just use your forearm strength to tighten them once they are fully seated.
It is a 1976 with 350, but it is not the original block and has had modifications. Part of the issue is i don't know what all was done to it. I found a invoice that showed the pistons had been replaced, cylinders bored, decked block, new camshaft, and several other things.
Is it not important to try and get the proper torque on the plugs? Since i couldn't use it anyway, i did just try to tighten it with a ratchet until it felt tight.
I started to check the gap on the plugs i pulled out, and they seemed to vary some. The range of the gap of the old spark plugs was within the gap of the new spark plugs, so i would presume it is ok? I'll check all of them when i get home.
Thanks for all the help!
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well, i think Bromley is on to something! I forced the choke to stay open, and the car started right up and stayed idling when i took my foot off the gas. i let it run for about a minute and then removed what was holding it open, the choke slammed shut and the car died. How long should it take for that choke to stay open after the car is running?
I dont understand why the car started right up with the choke forced open instead of closed. Maybe it was flooded and there was too much gas so the choke needed to be open to start the vehicle?
So i guess my choke isn't working?
I dont understand why the car started right up with the choke forced open instead of closed. Maybe it was flooded and there was too much gas so the choke needed to be open to start the vehicle?
So i guess my choke isn't working?
Melting Slicks
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From: Redruth Cornwall
Advanced
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From: Chandler az
well, i think Bromley is on to something! I forced the choke to stay open, and the car started right up and stayed idling when i took my foot off the gas. i let it run for about a minute and then removed what was holding it open, the choke slammed shut and the car died. How long should it take for that choke to stay open after the car is running?
I dont understand why the car started right up with the choke forced open instead of closed. Maybe it was flooded and there was too much gas so the choke needed to be open to start the vehicle?
So i guess my choke isn't working?
I dont understand why the car started right up with the choke forced open instead of closed. Maybe it was flooded and there was too much gas so the choke needed to be open to start the vehicle?
So i guess my choke isn't working?
I am in Scottsdale Arizona so we never need chokes hear.
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it looks like a manual choke, with no cable attached to it. I don't recall the position of it before, but i just pushed the lever to be completely open and it all seems fine now. I suppose there's no issue with just leaving it that way?
Drifting
Joined: Dec 2009
Posts: 1,349
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From: Porterville Ca
1) Always gap plugs. They may fit other engines and be gapped for something else. They may have been dropped enroute to your garage. Years ago my former boss spent about a week trying to diagnose why the engine he just rebuilt wouldn't start, plug gap was wrong. 40 hours wasted.
2) The choke restricts air/adds fuel, generally for cold temps and initial start. IE choke pull off and some sort of thermostat.
2) The choke restricts air/adds fuel, generally for cold temps and initial start. IE choke pull off and some sort of thermostat.