1981 Corvette HELP!!!

[Silver81Vette]

I have a 1981 Vette and it runs great, after some work done to the engine, and a little TLC, because it sat in a garage for years. I have a problem with something, and I dont know what. Everytime i hit a bump in the road, that jars the car somewhat, the tach jumps and the car acts like it wants to die. Only happens for a split second, then it runs fine. I have no idea, and I need help from someone who knows what to look for, I believe its definately something electrical, but I have not the slightest. I need help. Any advice would be great. Thanks!

 

[bill81vette]

1st,welcome to CAC!!!!
hope you enjoy the forums!!!!
be sure to check out the l-81 registry and register your vette if you haven't already do so!!!!!!!!

as far as your problem goes,I would check around the distributor 1st,and make sure everything is tight,the distributor cap is secure,all the wires are not falling out,check the back of the alternator,and make sure all the connections are tight on it.check all your grounds(there are a lot of them make sure they are clean(no corrosion) and tight)!!!check the wiring on the starter.
any of these could be your problem........good luck!!!!

 

[Silver81Vette]

Thanks!

Hey thanks for the advice. I'll post pictures of my shark here soon. It's my first Vette. Actually, the car was built about a month before I was born, so its got some sentimental value to it. I'll get a buddy of mine to help me out with the wiring and all that. It's just weird how it does that. If I hit alot of bumps in a row, it wants to die, but only for a split second. Crazy. Well, hey thanks alot! I appreciate it !! Also, is this a common problem for the 81's?, and also, I need to find a place that I can shop so I can re-cover my drivers' side seat. It has some age to it, and the leather is tore. I have Corvette seat covers, but I really want to start to restore it. Thanks again!

G.J. Costello
Wheeling, West Virginia

 

[GerryLP]

Hey thanks for the advice. I'll post pictures of my shark here soon. It's my first Vette. Actually, the car was built about a month before I was born, so its got some sentimental value to it. I'll get a buddy of mine to help me out with the wiring and all that. It's just weird how it does that. If I hit alot of bumps in a row, it wants to die, but only for a split second. Crazy. Well, hey thanks alot! I appreciate it !! Also, is this a common problem for the 81's?, and also, I need to find a place that I can shop so I can re-cover my drivers' side seat. It has some age to it, and the leather is tore. I have Corvette seat covers, but I really want to start to restore it. Thanks again!

G.J. Costello
Wheeling, West Virginia

G.J.,

Do the lights flicker when it acts like its going to stall? That could be a good secondary indication as well of an electrical problem.

Does it do it on an unusually steep road or street while driving up it?

If it also does it while going up on a steep street, then perhaps you could have an issue with the carburetor float level. Hard acceleration or decelerations stalls also reveal float level issues.

 

[Silver81Vette]

Gerry,
The lights do not flicker at all. This thing runs like the wind blows to be honest, but if i hit a series of bumps (covered pot holes, etc...) this thing willl want to die. But as for acceleration, etc..., couldnt be more happier, just cant find out what this is... Also when I get it up to about 80-85mph, and goose 'er, the tach flies all over the dashboard and it wants to cut out, a gradual acceleration it wont do it. I have no idea here... The carb was re-built last year (guy who owned it before me had it done). I just replaced all the fuel lines, brake lines, vapor lines, dropped and overhauled the fuel tank, new distributor, new diverter valve, new air check valves, new distributor, plugs, wires, etc... but NO flicks from the dashboard at all. the car dies, i pull over, throw it in PARK, and it starts right back up, and I can drive away. It's very weird if you ask me. Wonder how much it would cost to replace the float, or maybe the float is gummed up??? Wonder if I spray some carb cleaner in the carb??? Thanks for all the help, and I appreciate all the help in the future, too! ***Also, the guy that had it before me took the catalytic converter off the car and ran a straight pipe for the dynaflo exhaust. Does this car absolutely NEED this catalytic converter?? just wondering. Thanks again!

 

[cheftl13]

Not sure if this will help but, I was having problems with my 81', I could get it to idel right or open up the four barrels. 2 mechanics and a couple hundred dollars of carb work, found out that it was the the computer. We replaced it, my car has never run better since. ??? May be something to consider, if not already. Mario

 

[bill81vette]

Gerry,
but NO flicks from the dashboard at all. the car dies, i pull over, throw it in PARK, and it starts right back up, and I can drive away. Thanks again!

this was a sure symptom of the computers in this era when they went bad...not just vettes but ALL the computers would just flat out die going down the road,pull over start back up and your on your way again...

 

[GerryLP]

Gerry,
...***Also, the guy that had it before me took the catalytic converter off the car and ran a straight pipe for the dynaflo exhaust. Does this car absolutely NEED this catalytic converter?? just wondering. Thanks again!

No, the cat wont affect it if is missing.

Definitely it seems that something is loose and causing the stalls. Suggest get this Vette on a lift and look underneath it. Loose ground? Loose wire somewhere? Check the wires to the distributor perhaps?

Like Bill says -perhaps the computer? Check the computer for codes to see if it perhaps gives you a clue as to possible causes.

 

[cheftl13]

more than likely its the computer, for 100 bucks or so its worth the fix, ive come to see that the computer is a major malfuction in our 81' corvettes, before i changed it, i put the car on the code checker, it came up that i had a bad sensor in my carb, changed it, didnt work. My car would go in lymp mode after awhile. As far as the cat is, it doesnt hurt your car, just your wallet and ozone, lol.

 

[L48]

My 75 was having some similar symptoms, though it never took to stalling out. The control module in the HEI was the culprit. It's a longshot but I spent many hours fixing the wrong things before changing a $20 part.

 

[Silver81Vette]

Where is this ECM located? Is this a job that I could probably do with a buddy, or is this something that i'll have to take to a mechanic? I found a reconditioned ECM on www.ecklers.com for $119.00. Not a bad price. It also says use existing chip. If the module is bad, wouldnt the chip be bad also? Just throwing that out there. Would anyone suggest replacing both the ECM and the ignition module? All the help and advice is much appreciated!

 

[bill81vette]

the ecm is located in with the battery behind the drivers seat,on the front wall.couple of bolts an the wiring harness and your done!
I don't know if the chip is bad just b/c the module is bad....
good luck!!!

 

[Sensei]

If the module is bad, wouldnt the chip be bad also?

No, but you can get a performance chip for about $120 if it will make you feel better.

Would anyone suggest replacing both the ECM and the ignition module?

No, if it ain't broke, don't fix it! Figure out which, if either, is bad and replace it./quote]

My best advise; figure out what the problem is first, then fix the problem. I've seen guys spend hundreds in frustration replacing everything on their car, ditching the computer, carb, distributor, etc and still have the same problem they started with. First off, this car will run with the computer disconnected. Before you buy a new computer, I'd disconnect it and see if you still have the problem. If so, it's not the computer. God bless, Sensei

 

[like2drive]

another possibility

I had to push my vette out of the road adtwice before I found the problem, that just might be yours also. there is a 3 wire connection under the distributor. one of the 3 wires is a male connection into the female which can, by engine torque movement, gravity, etc...fall out and completely kill the engine. After I found the problem, I taped the connection very securly and have had no more dead engine.

good luck, jim

 

[wdilwort]

I had the same problem on my 1982. Although my engine is injected the computer wiring may be simular. I had my car to three repair shops for the same problems you had and after replacements of plugs, wires, air clearers, caps, etc. and several hundred dollars out of my pocket the problem still remained. I pulled out my shop manual and it said to check the computers in-line fuse. It bypasses the wiring harness and goes directly to the battery case. The inline fuse is in the case with th battery and directly attached to the battery. It was damaged by battery acid. I replaced the in-line fuse assembly for three dollars and the problem is gone!

 

[72VETTE454]

The best way to check if a computer is bad is to remove it but leave it plugged in, then start the car. Take the computer with both hands and try to twist it as much as possible in all directions, it's kind of difficult because of the metal case. See if you can get it to act up that way. If not, try hitting it with the palm of your hand or some SOFT blows with a rubber mallet. You don't want to crush it, but you're not dealing with an egg either. The problem is that the circuit board inside cracks and if yours is cracked, this will tell you.

 

[Silver81Vette]

Well,
This seems really weird, but i got back into the battery compartment, messed with the connections with the battery, and also the ECM, got under the hood, jiggled a couple of wires, hoses, etc... and this car has never ran better over the past couple days. Does this seem weird to anyone? maybe something was stuck, or whatever... just seem weird. No stalling, jumping in RPM's, no spitting, no sputtering, etc... runs like its brand new. I dont know... anyone have any imput???

Thanks:confused

 

[fedcop90vette]

I had a simular problem on my 81 vette, seemed I ran over something and I cut the battery wire that runs under the car....didn't cut it all the way through but enough to really be a pain......something to look at....don't forget the wave!

 

[corvetteweslo]

its def the tach wire going to distributor coming loose disconnect it and it will run great this happend to me.

I had a simular problem on my 81 vette, seemed I ran over something and I cut the battery wire that runs under the car....didn't cut it all the way through but enough to really be a pain......something to look at....don't forget the wave!

It can also be the negative wire on the distributor. I guarantee that's all it is

 

[Tom Bryant]

Well,
This seems really weird, but i got back into the battery compartment, messed with the connections with the battery, and also the ECM, got under the hood, jiggled a couple of wires, hoses, etc... and this car has never ran better over the past couple days. Does this seem weird to anyone? maybe something was stuck, or whatever... just seem weird. No stalling, jumping in RPM's, no spitting, no sputtering, etc... runs like its brand new. I dont know... anyone have any imput???

Thanks:confused

Must have been a little corrosion on a connector causing a poor connection intermittently. Wiggling and checking the wiring plugs probably reinstated the connection. A lot of these connectors are low voltage and it doesn't take much corrosion or tarnish to interfere with the connection.

Tom