1980 C3 stalls out
Thread Starter
Heel & Toe
Joined: Sep 2013
Posts: 15
Likes: 0
1980 C3 stalls out
hi there
i have a 1980 C3 with an L82. mostly standard except for hooker Headers, and an upgraded electric cooling fan.
recently i felt a slight hesitation / loss of power at 60mph. very slight but noticeable.it is also much slower off the line.
then i thought i had a vacuum leak because the lights would not function normally and the air con vents would not work properly. after checking for vacuum leaks, found a few loose-ish hoses but nothing major. but lights and vent went back to normal.
i continued chasing the power loss issue. decided to disconnect EGR and plug hose to see if it was the culprit. but it did not turn out to be it.
changed spark plugs recently and also flushed the radiator.
now it runs fine until the temperature is up to normal operating temperature. then it will stall out when in gear. the lights go dim in the dash as well as all gauges and as well as the headlights then it quits running. if in nutria or park , its fine.
its also fine while warming up.
any ideas where to look next ?.
thanks all
i have a 1980 C3 with an L82. mostly standard except for hooker Headers, and an upgraded electric cooling fan.
recently i felt a slight hesitation / loss of power at 60mph. very slight but noticeable.it is also much slower off the line.
then i thought i had a vacuum leak because the lights would not function normally and the air con vents would not work properly. after checking for vacuum leaks, found a few loose-ish hoses but nothing major. but lights and vent went back to normal.
i continued chasing the power loss issue. decided to disconnect EGR and plug hose to see if it was the culprit. but it did not turn out to be it.
changed spark plugs recently and also flushed the radiator.
now it runs fine until the temperature is up to normal operating temperature. then it will stall out when in gear. the lights go dim in the dash as well as all gauges and as well as the headlights then it quits running. if in nutria or park , its fine.
its also fine while warming up.
any ideas where to look next ?.
thanks all
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
Check to make sure the carburetor bolts are CORRECTLY torqued...because they can sometimes loosen up and create a vacuum slight vacuum leak. Also the top screws of the carb ...check those.
Not knowing what your idle RPM's are when it is in gear and warmed up...hard to say anything.
I am in agreement that the ignition may need to be looked at with the information you provided.
Not knowing if you have really dirty air filter. And if your CHOKE is actually operating correctly....because you did not state what your fast idle was when you cranked it up cold.
DUB
Not knowing what your idle RPM's are when it is in gear and warmed up...hard to say anything.
I am in agreement that the ignition may need to be looked at with the information you provided.
Not knowing if you have really dirty air filter. And if your CHOKE is actually operating correctly....because you did not state what your fast idle was when you cranked it up cold.
DUB
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
this or a crack in the coil that once it heats up it opens enough to let moister in and kills the engine. I suppose once it's cooled off it starts and runs fine until it get's up to temp?
Thread Starter
Heel & Toe
Joined: Sep 2013
Posts: 15
Likes: 0
Thanks
air filter clean. The cold start up rpm 1400 then after warming up it drops to 800 rpm unless air conditioning is on then it rises to 1200 rpm.
air filter clean. The cold start up rpm 1400 then after warming up it drops to 800 rpm unless air conditioning is on then it rises to 1200 rpm.
Check to make sure the carburetor bolts are CORRECTLY torqued...because they can sometimes loosen up and create a vacuum slight vacuum leak. Also the top screws of the carb ...check those.
Not knowing what your idle RPM's are when it is in gear and warmed up...hard to say anything.
I am in agreement that the ignition may need to be looked at with the information you provided.
Not knowing if you have really dirty air filter. And if your CHOKE is actually operating correctly....because you did not state what your fast idle was when you cranked it up cold.
DUB
Not knowing what your idle RPM's are when it is in gear and warmed up...hard to say anything.
I am in agreement that the ignition may need to be looked at with the information you provided.
Not knowing if you have really dirty air filter. And if your CHOKE is actually operating correctly....because you did not state what your fast idle was when you cranked it up cold.
DUB
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
What is your RPM...in gear...before it dies????
AND...when it is 'dying'...is it dying when you are going from PARK to drive or reverse???
Your RPM's should go up about 100 RPM's when you have the A/C on. It is not your problem...but just letting you know.
DUB
AND...when it is 'dying'...is it dying when you are going from PARK to drive or reverse???
Your RPM's should go up about 100 RPM's when you have the A/C on. It is not your problem...but just letting you know.
DUB
Thread Starter
Heel & Toe
Joined: Sep 2013
Posts: 15
Likes: 0
Ok. Obviously I'm a novice so bear with me. In gear rpm 900 for 25 seconds then starts to drop (only when fully warmed up) headlights and dash lights start to dim as rpm drops . Then the engine dies.starts up right away first time. But dies same way.same if going to park or reverse.
I can keep it going if I fettle the gas peddle.
thanks a lot
I can keep it going if I fettle the gas peddle.
thanks a lot
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
Safety Car
Joined: Sep 2012
Posts: 4,688
Likes: 41
From: Palm Harbor, Florida
Be sure there is no arcing from spark plug wires/boots. I had an arcing problem that caused me to misfire and sometimes stall. I have headers. I had some "socks" over the boots that were real close to the pipes, but the rubber had burned through enough to arc through the sock. Visually inspect all 8 boots, removing any and all socks.
Any back fire through the carb?
Any back fire through the carb?
Last edited by Doug1; Oct 14, 2015 at 09:06 PM.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
You may have a failing fuel pump. Check it by disconnecting the fuel line to the carburetor, stick a 3/8" hose onto the fuel line, then stick the other end of the hose into a coffee can. Crank it for 30 seconds then measure the amount of gasoline that came out. It should deliver 1-1/2 pints in 30 seconds.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
I seriously doubt that is is fuel pump related. 'Loss of power' would not be fuel related...because if it was running out of fuel it would sputter and hiccup. BUT...what do I know...anything is possible.
The problem is when it gets put under a load....at operating temp ...at idle in PARK...then going into gear...which to me...I feel your choke may not be set right.....BUT...still waiting on a response to my last post.
DUB
The problem is when it gets put under a load....at operating temp ...at idle in PARK...then going into gear...which to me...I feel your choke may not be set right.....BUT...still waiting on a response to my last post.
DUB
Safety Car
Joined: Sep 2012
Posts: 4,688
Likes: 41
From: Palm Harbor, Florida
Could be fuel as stated, fuel filter been replaced lately, they are cheap enough. Since it needs more gas at the higher RPM's.
The choke can be visually inspected, could be that too.
The choke can be visually inspected, could be that too.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
But when it dies when put into gear when it is warmed up or being warmed up...does not need more fuel....But if the choke plate is not correct....this can cause a problem.It can be BOTH...or something else.....still waiting on a reply.
DUB
Safety Car
Joined: Sep 2012
Posts: 4,688
Likes: 41
From: Palm Harbor, Florida
So when it's warm, it should be fully open. That's easy enough to see.
Yeah, where's the feedback!? Lol, that is a problem that would drive me crazy, I would want that fixed ASAP.
Last edited by Doug1; Oct 15, 2015 at 08:04 PM.
Thread Starter
Heel & Toe
Joined: Sep 2013
Posts: 15
Likes: 0
Thanks for all the input, and sorry for the late reply but was working .
OK DUB I did the checks you mentioned.
Rpm in P without Air conditioning 800 when cold and in Park. If I shift to D or R drops to 600.
Rpm in P without Air conditioning at operating temprature 500. If I shift to P or D rpm drops to 400 and dies.
Fuel pump changed 3 months ago. But did not change filter.
Checked the bolts and screws on the carb . They were not very tight so I tightened . But no change.
Checked the spark plug wire visually. Nothing obvious.
Checked could pack on the distributer for cracks. Nothing visable there.
How do I set the choke?
Thanks a lot
OK DUB I did the checks you mentioned.
Rpm in P without Air conditioning 800 when cold and in Park. If I shift to D or R drops to 600.
Rpm in P without Air conditioning at operating temprature 500. If I shift to P or D rpm drops to 400 and dies.
Fuel pump changed 3 months ago. But did not change filter.
Checked the bolts and screws on the carb . They were not very tight so I tightened . But no change.
Checked the spark plug wire visually. Nothing obvious.
Checked could pack on the distributer for cracks. Nothing visable there.
How do I set the choke?
Thanks a lot
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
Your curb idle setting is too low. Give it a 1/4 to 1/2 a turn and see what happens. You can ALWAYS put it back to what you turned it if needed...just make notes so you do not forget.
Your fast idle is really low also. It should be much higher....like 1350 RPM's ( for example...but do not have my manual at home to give you a specific RPM to set it at. when cold...and then when it is warmed up a bit and you tap the accelerator pedal...it should drop.
Setting the choke is specific. Lets see if turning up the curb idle a little bit will help you first.
DUB
Your fast idle is really low also. It should be much higher....like 1350 RPM's ( for example...but do not have my manual at home to give you a specific RPM to set it at. when cold...and then when it is warmed up a bit and you tap the accelerator pedal...it should drop.
Setting the choke is specific. Lets see if turning up the curb idle a little bit will help you first.
DUB
Thread Starter
Heel & Toe
Joined: Sep 2013
Posts: 15
Likes: 0
Thanks DUB
I plan to work on it today so ill give it a try.
I plan to work on it today so ill give it a try.
Your curb idle setting is too low. Give it a 1/4 to 1/2 a turn and see what happens. You can ALWAYS put it back to what you turned it if needed...just make notes so you do not forget.
Your fast idle is really low also. It should be much higher....like 1350 RPM's ( for example...but do not have my manual at home to give you a specific RPM to set it at. when cold...and then when it is warmed up a bit and you tap the accelerator pedal...it should drop.
Setting the choke is specific. Lets see if turning up the curb idle a little bit will help you first.
DUB
Your fast idle is really low also. It should be much higher....like 1350 RPM's ( for example...but do not have my manual at home to give you a specific RPM to set it at. when cold...and then when it is warmed up a bit and you tap the accelerator pedal...it should drop.
Setting the choke is specific. Lets see if turning up the curb idle a little bit will help you first.
DUB
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
hi there
i have a 1980 C3 with an L82. mostly standard except for hooker Headers, and an upgraded electric cooling fan.
recently i felt a slight hesitation / loss of power at 60mph. very slight but noticeable.it is also much slower off the line.
then i thought i had a vacuum leak because the lights would not function normally and the air con vents would not work properly. after checking for vacuum leaks, found a few loose-ish hoses but nothing major. but lights and vent went back to normal.
i continued chasing the power loss issue. decided to disconnect EGR and plug hose to see if it was the culprit. but it did not turn out to be it.
changed spark plugs recently and also flushed the radiator.
now it runs fine until the temperature is up to normal operating temperature. then it will stall out when in gear. the lights go dim in the dash as well as all gauges and as well as the headlights then it quits running. if in nutria or park , its fine.
its also fine while warming up.
any ideas where to look next ?.
thanks all
i have a 1980 C3 with an L82. mostly standard except for hooker Headers, and an upgraded electric cooling fan.
recently i felt a slight hesitation / loss of power at 60mph. very slight but noticeable.it is also much slower off the line.
then i thought i had a vacuum leak because the lights would not function normally and the air con vents would not work properly. after checking for vacuum leaks, found a few loose-ish hoses but nothing major. but lights and vent went back to normal.
i continued chasing the power loss issue. decided to disconnect EGR and plug hose to see if it was the culprit. but it did not turn out to be it.
changed spark plugs recently and also flushed the radiator.
now it runs fine until the temperature is up to normal operating temperature. then it will stall out when in gear. the lights go dim in the dash as well as all gauges and as well as the headlights then it quits running. if in nutria or park , its fine.
its also fine while warming up.
any ideas where to look next ?.
thanks all
I also disconnected/plugged all vacuum lines going to/from the thermal actuators on the air cleaner. The flap in the passenger snorkel always seemed to be partly closed. I fixed them all in OPEN position to maximize airflow into the carb.
Thread Starter
Heel & Toe
Joined: Sep 2013
Posts: 15
Likes: 0
Thanks TedH
It seems i have other problems, but will look into a vac leak once they are solved.
It seems i have other problems, but will look into a vac leak once they are solved.
I removed/replaced the thermal vacuum switches on my '80 L48 that are in the intake and water inlet. I found they were a constant issue for loss of vacuum. aftermarket isn't much better. Once I removed them and re-routed the hoses vacuum hoses on intake area to compensate (remove EGR, EFE), I kept evap canister vacuum hoses along with all but the rear vacuum hose entering the base of carb (not to be confused with the line/hose for power brakes). Bypassing all of this mess really helped resolve vacuum leaks and improved idle performance along with a good carb rebuild by a reputable tuner (Lars).
I also disconnected/plugged all vacuum lines going to/from the thermal actuators on the air cleaner. The flap in the passenger snorkel always seemed to be partly closed. I fixed them all in OPEN position to maximize airflow into the carb.
I also disconnected/plugged all vacuum lines going to/from the thermal actuators on the air cleaner. The flap in the passenger snorkel always seemed to be partly closed. I fixed them all in OPEN position to maximize airflow into the carb.