1985 cherokee with the 2.8l v6... im having an issue were it does a bunch of small backfires and cackling noise at idle and also after deceleration. ive also lost quite a bit of power. when i give slight gas, idle smooths out and the popping seems to go away. i also get occasional much louder pops during acceleration / driving but these are not as common. sometimes, but not always, after complete decel the idle will drop low enough that the engine will die. ive also noticed a gas smell inside the vehicle. in response to some other posts ive made, people have said to replace / rebuild the carb and im thinking that its time. i guess my main question is i have obvious carb issues will an unbalanced fuel mixture cause the popping? also, with backfiring my first guess was a timing issue but i just timed it at 10 degrees which is what the hood sticker calls for (+ - 2). i played with allowances both above and below 10 degress but was unable to find a sweet spot. ive also replaced the cap, plugs, wire, repaired vacuum leaks, new egr, new pcv, any thoughts are appreciated as this POS motor has me ready to find a cliff and cut losses.

 

Sounds like a 2.8L... yeah carb needs some love. Fuel mixture is off at different throttle positions.

 

Backfire through the carb or out the exhaust?
Being a GM engine, that's a Rochester carb? NAPA normally stocks the rebuild kits for those- not very expensive. Make sure it's tight to the manifold, air leaks after the butterfly will give you lean backfires..

 

I checked for smugness on the manifold and its right, however i have no idea about the integrity of the gasket. the backfire seems to be coming out of the exhaust but I'm not sure it doesn't also happen at the throttlebody

 

Oh, just on GP, do take a look inside that new cap. See if there might be condensation or anything at all that might let the spark run a wrong route. Easy enough. 85?..If there is a condenser anywhere you might consider changing it. Just that they are such tricksters, and cheap. Some easy stuff there.

I set timing at operating temp, accelerating from 30 to 50 in high gear, with the fuel I'm going to run, so there is a "ghost of a ping". Otherwise said, myself I want all the advance I can get with out a pinging problem.

"i also get occasional much louder pops during acceleration"....Under acceleration the spark will try a little harder to find another way to ground. Also a weak spark may just pain not make it. Good blue spark? Plugs clean and properly gaped.

Besides that our fuel sucks for carbs. I was told there is "nothing" in the gas. Well I have about two gallons of that "nothing" that I have gotten out of cans, tanks, and carb bowls. It burns, makes great week killer, but most of my stuff wont run on it, although with allot of choke some will try. I guess the ethanol blend absorbs water when it can, then separates. Really fun on a pull start generator in the middle of the night!

I guess that crap works out better being reticulated past the pressure regulator in an injected system, than it does sitting in a carb bowl.

If there is not too much in there sometimes I will rev it, and clamp off the air, like choking. That might suck stuff past the main jets and help clear it out. Anyway that's been all to common for me with the new fuel and carbs.