yea so a little while ago i took the air filter out of my truck..(was changing it.) and decided to start the truck without the air filter or any of the intake on the truck..(took it off for other reasons) and then i gave it some throttle...and theres what seems to be a backfire inside my carb...theres a very loud popping if i give it full throttle...and its spraying something out of the top of the carb...remember...i also have only 3/4 throttle driving anywhere..(because of what sounded like and exhaust leak...but turns out to be this carb problem)..i DO have an exhaust leak..the lower back bolt on the manifold is stripped...so i know it leaks there...but what is up with this "backfiring" of the carb..its VERY loud...sounds JUST LIKE AN EXHAUST LEAK..but its coming out of the top of the carb...what the hell could this be...thanks for any help guys

 

*bump*..anyone???

 

If its backfiring through the carb its probably a lean miss. You might have to rejet the carb or clean it up cause it might not be getting enough fuel.

 

before you dive into the carburetor- replace the fuel filter
if that don't help, look in the sight glass on the side of the carb and see how much fuel is in the float chamber. the fuel level should be in the center of the glass. if it's not, the float could be sticking or the fuel pump could be going bad.

 

When checking the float level, does it need to be done with engine off or running? Or should it not matter?

 

Should be done with both, the level theroetically shouldnt change.

If you took the intake completely off (like unhooking hoses) then you got a vaccum leak. Unless you plug those up the engine won't run right =) You can safely take the aircleaner out, or the lid off which is fine.

If its a stock carb you can drill out the metal plug to get to the mixture screw. It's on the pass side, right in the middle at the bottom. Find the 85 FSM on here and look at it for a diagram.

Not to sure on the backfiring. =/

 

good advice from abe..uhm the only other thing i can say is maybe a bee got sucked in whilst you were open..hehe j/k

 

see now i've been told its not fuel related at all...by a few people...and one person said it could be the accelerator pump..one person said it could be an exhaust leak...another said it could be a dirty carb...(i did get a tankfull of bad gas a while back..clogged up my fuel filter and everything..)..im leaning towards the dirty carb...i've been told to run a very good octane booster through it...so...whats the BEST octane booster???...i mean..at the local auto parts store..there are a few different kinds..which is best?...

 

instead of octane booster, how about a can of seafoam in the fuel tank?
if that doesn't help, some spray carb or injector cleaner sprayed into the fuel bowl with the engine running may help loosen stuff up.
if stuff got through the filter and into the carb, any one of the passages or jets could be clogged.
vacuum leaks could cause a lean mix and backfiring up through the carb.
incorrect ignition timing could
incorrect valve adjustment could
a worn camshaft could

but start with a new fuel filter, check the fuel level in the float chamber, maybe the cleaner in the tank or spray the carb and look for vacuum leaks.