81 Vette has issues advice please
Thread Starter
Intermediate
Joined: Aug 2006
Posts: 34
Likes: 0
From: Morgan's Point Texas
81 Vette has issues advice please
I am posting this for my boss. I told him this would be a great place for info. 
(This is exactly what he sent to me so if theres any questions I will get him to clear them up for ya!) Thanks for any help
"I have a stock 1981 Corvette; I had the carb rebuilt by a company in California, the EPROMs were replaced by not "set up" the carb was installed but my mechanic did not have the equipment to set the chips or adjust the carb; It runs but is running very rich, needs to be set up properly......
My brake light is coming on , I pump up the brake and it takes care of it temporarily, calipers have been replaced with rebuilt ones with chrome linings and pistons........ car has not been run that much, may be leaking brake fluid but I haven't found where..........."
(This is exactly what he sent to me so if theres any questions I will get him to clear them up for ya!) Thanks for any help"I have a stock 1981 Corvette; I had the carb rebuilt by a company in California, the EPROMs were replaced by not "set up" the carb was installed but my mechanic did not have the equipment to set the chips or adjust the carb; It runs but is running very rich, needs to be set up properly......
My brake light is coming on , I pump up the brake and it takes care of it temporarily, calipers have been replaced with rebuilt ones with chrome linings and pistons........ car has not been run that much, may be leaking brake fluid but I haven't found where..........."
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
I can't help with the computer or carb, but the brakes is an easy one.
First, he needs to make sure he has a full reservoir for both the front and rear circuit. If the brake light is coming on that usually means there is air trapped in the system and it's tripping the switch. If it gets stuck one way or the other the light turns on.
The temp fix is to bleed the brakes...very thoroughly, but to fix the problem he may have to have all rotors checked for runout, and have the rotors turned or shimmed to limit the runout.
Runout is basically when the rotor wobbles in the caliper. This causes an air pump effect with the calipers, and even though he has S/S sleeved calipers, they are sucking in air...which gets caught in the lines.
Hope this has helped.
First, he needs to make sure he has a full reservoir for both the front and rear circuit. If the brake light is coming on that usually means there is air trapped in the system and it's tripping the switch. If it gets stuck one way or the other the light turns on.
The temp fix is to bleed the brakes...very thoroughly, but to fix the problem he may have to have all rotors checked for runout, and have the rotors turned or shimmed to limit the runout.
Runout is basically when the rotor wobbles in the caliper. This causes an air pump effect with the calipers, and even though he has S/S sleeved calipers, they are sucking in air...which gets caught in the lines.
Hope this has helped.
Race Director
Joined: Jul 2004
Posts: 12,694
Likes: 329
From: Scottsdale Arizona
The carb statements don't sound right. If the carb was set up properly and the computer is not working, it will run rich (by design). What doesn't sound right is the statement about EPROMs. I believe there are one or two PROMs on the computer module, but I very much doubt that there would be a reason or expertice to replace these. The whole computer unit comes in a nice, contained, silver box that is in the battery compartment. These are readily available on eBay or even some of the parts dealers (like Checker) have used ones. The easiest thing would be to replace this and see if it solves the problem. If not, there are a number of diagnostic steps and possibilities.
To the best of my knowledge no one out there has the information to burn the PROMs. I'm fairly certain that no shop would have this nor the diagnostic equipment to say that one is faulty. Replacing these just doesn't make sense.
To the best of my knowledge no one out there has the information to burn the PROMs. I'm fairly certain that no shop would have this nor the diagnostic equipment to say that one is faulty. Replacing these just doesn't make sense.
Last edited by CA-Legal-Vette; Jun 6, 2008 at 11:53 AM.
Melting Slicks
Joined: Mar 2006
Posts: 2,465
Likes: 0
From: Orange Park Fl
You can check trouble codes on an '81, but you must have an older diagnostic computer or one of the commercial ones that will check any system (the ones at Autozone won't work). A dealership or a well equiped garage should be able to check. I'd start there before replacing anything. Get a 1981 Corvette GM Service Manual on Ebay. It will give you the diagnostic proceedures to actually find and fix the problem with the least frustration. God bless, Sensei
Race Director
Joined: Jul 2004
Posts: 12,694
Likes: 329
From: Scottsdale Arizona
You probably won't find a dealership with the equipment to read these diagnostics any more. The technology is decades obsolete. You can read fault codes yourself anyways.
http://forums.corvetteforum.com/show....php?t=2044771
Scroll down and the procedure is spelled out.
http://forums.corvetteforum.com/show....php?t=2044771
Scroll down and the procedure is spelled out.
Melting Slicks
Joined: Mar 2006
Posts: 2,465
Likes: 0
From: Orange Park Fl
Actually, the big multi K$ diagnostic machines the dealerships have do still read these ancient computers (at least all the dealers around here). It's the cheap hand held readers that won't work. God bless, Sensei
