Random backfire

[85mustangkiller]

Before I buy a part I dont need I thought I would ask for help. I got a 83 NA regal for parts. It starts up runs fine for awhile then backfires when you try to give her gas. A few blocks latter I can stomp on it and she will take off just fine with no backfire. And a little latter backfires returns. The Backfire is on the carb side, Im kinda stumped, thinking its something with the HEI. Any ideas.

 

[WarWagon]

Could perhaps be a number of things.
First I'd check and verify the ignition timing then look at the accel pump on the carb or the carb itself.

 

[charlief1]

You need a scan tool of some sort to see what the timing is doing. It sounds like it needs some advancing to me.

 

[85mustangkiller]

So far I have pulled the distributor, and made sure it was at TDC on one. Didnt really change anything. I got a spare carb I will put on and see what happens. I have it advanced alot, its the only way it would run. If I Retard it down were it should be it starts backfiring a bunch when you give it gas. But its just fine at idile. thanks for the help.

 

[charlief1]

If you've advanced it quite a bit did you make sure to diable the ESC before you timed it? If you didn't this may be your problem.

 

[b4black]

Is the ECM working? Does the 'check engine' light come on and then go off when you start the engine?

 

[85mustangkiller]

I will have to check if its coming on in the morning, dont think people would like me starting her at 11 at night. I know its not staying on I would have noticed that. Im trying to get her running good, cause my buddy wants to buy it for his 82 firebird(has chevy 2.8 in it right now what I pile of junk) Just dont want to sell him an engine that might have a burned valve or something worse.

 

[85mustangkiller]

update, no check engine light. also I think the fuel pump is bad. It takes a few cranks to build fuel back to the carb. I can shut her off and come back an hour latter and she will fire right up. butif I let her sit for a long time My fuel drains off. Could this have an effect on the back fire?

 

[b4black]

I don't think you followed me (or I didn't explain it well enough). The check engine light needs to come on when you start the car, then qucikly turn off. If it never turns on, then the light id burn out or disabled. This is common on old 1980's cars. Someone messes with the engine and/or disables the the computer. They will run like crap without a computer.


Read this page and see if you can pull a code 12. If you can, the ECM is working. (The page applies to non-turbo V6's as well.)Malfunction Codes Reference

 

[85mustangkiller]

I will give that a go, Thank you.

 

[85mustangkiller]

Well Im about 80% shure I got a lifter thats sticking. She starter making a sound like the valve is hitting the top of a piston. O well shes a parts car so no big deal.