exodus82

I have an 81 with the stock 12a. I changed my fuel filter and pump because i thought i wasnt getting enough fuel. That was not the problem. It sounds like there is a vacuum leak somewhere but i dont know where it could. I checked my vacuum pressure and it was all over the place. It is also backfiring and this also just started when the other problems started. Which of the coloured selenoids controls backfiring??

mwatson184

Get a can of carb cleaner and spray it around the engine bay while idling. The idle will change when you spray around a leak.

The backfiring could also be caused by bad ignition componentes. Pull the wires off of the spark plugs one by one to see if they are firing. Check your cap and rotor, and check to make sure your ignitors are firing off the coils.

-Marques

exodus82

Ill try the carb cleaner. All the plugs are firing. Everything is new. Accel coils and wires. New plugs.

nlc1179

when is it backfiring?

exodus82

When the RPMs are decreasing rapidly, when I let of the gas after reving it high.

slashdawg00110

Do you hear a honking noise at idle? If so, check the shutter valve. It's located at the rear of the carb. There's a large hose running from the valve to the bottom of the air cleaner.

slashdawg00110

Another idea. Before you yank the emissions stuff, try to get your vacuum leaks under control. That way, you'll know it runs well before you start ripping stuff off. If you go ahead and remove the emissions controls and it runs crappy after, your troubleshooting is limited to the few things you did to remove the emissions.

The vac hoses are cheap. You can get the little hose in bulk from lots of places. I got a bunch from a hardware store down the street from my house. Just get about 20 feet and start replacing the old, brittle stuff you have on there now.

brianw

I thought about that but as you said 20' just to get started. That's a lot of work if you plan on taking it all off anyway.It's a good way of doing things but I wasn't into it.I pulled everything and started from there.Pretty much just ran all new lines to be sure.It would have taken forever to fix all the stock lines,they pretty much fell apart when I tried to remove them.

Have you tried the carb cleaner yet?

slashdawg00110

I see what you mean. Some of the effort (well, most) and some of the vac tubing will be wasted. But I figure it's not a bad idea to get the car running stock and then go from there. It eliminates some variables when things don't work once you've yanked the rat's nest. Not that I did it that way. Just hindsight talking.

I mean, if you're pulling the rat's nest because you think it's f#$ing up, then fix it first. If you're pulling it because you feel like it or some other reason, then pull it and deal with the issues later.

The nice part about pulling a working emissions setup is that you can a) put it back on if you need to and b) you can sell it as "working".

Spraying carb cleaner is a great way to find vacuum leaks. As far as the backfiring goes, check your AAB, too.

exodus82

Im gonna try carb cleaner when i get back from school. I already fixed my shutter valve last year because it was honking.