fuel problem.....i think

[outlawtorn]

Well last week on the way home from school the blazer started to act like it was mis-firing badly and/or starving for fuel...i limped it home and replaced my timing chain thinking that it had just slipped a tooth (my distributor was turned quite aways from where it usually was). After installing the chain, i timed it correctly and it still ran the same. So then i checked the fuel pump and it still pumped stronly. I was lost so i took the fuel filter out for ****s and giggles and it was clogged so i replaced it. All was good for about 4 days and it is doing the same thing again.

Today i replaced the fuel filter again and took the carb off and cleaned it, to no prevail. So what could this be>? Its a SB400 and the carb is a 4 barrel q-jet.

 

[dyeager535]

One of the things I'd check when it starts acting up again is how much fuel is in the carb. Not very precise, but remove the air cleaner and while looking down the primaries, move the throttle and see if a strong jet of fuel shoots out. Not sure how many "shots" a typical carb will get off of a full float bowl, but when my truck was starved of gas (stuck float I suspected) I tried this, and with no fuel coming out, knew gas wasn't getting into the float bowl for whatever reason.

Imprecise test, but if you get a "pumpshot baseline" when it's running fine you should have something to compare it to. I don't know of any other way to test it.

Anything that you can always do to replicate the problem? Prolonged idling, high engine temps, low engine temp, accelerating, cruising, etc?

I guess this needs a disclaimer, don't burn your face. Not sure why the fuel would ignite, but I wouldn't put my eyes an inch from the carb while testing this.

 

[outlawtorn]

Well i found a HUGE vaccum leak that i overlooked for some dumb reason. My rear seal on my intake blew out lol. So ill replace that tomm. and see what happens. I did the fuel check btw and it did shoot a good jet still. Hopefully the intake was the problem if not ill drop my tank and check for clogs in that area.

 

[dyeager535]

Use RTV, not the gaskets.

 

[outlawtorn]

Yea thats what i do... i guess the PO messed with the intake.