Major Q-jet Mystery

get a fuel pressure gauge and check your pressure. make sure the return is open. if pressure is still bad.take the sock off the fuel intake make sure you have a inline filter before the carb never use one before the fuel pump. sounds like possible vapor lock especially if return is plugged

 

100 bucks says it's the sock. That explains the flaky black stuff I'm finding and the surging after a little highway driving. Debris is probably clogging the sock which itself maybe getting sucked up the end of the sending unit. That sock is 36 years old and I bet is restricting gas flow even without any debris. It's starving the engine for fuel and causing a lean-out which shows itself as a backfire through the carb.
I'll pull the sock off tomorrow and give it a go.
As for the vent, what's to stop me from capping the vent tubes on the tank and adding a venting gas cap? How much pressure is the tank supposed to hold?
Tanks again everyone has been very helpful.

 

Corn, pure corn,,,,:laugh: :laugh: Tanks again?????
Yep, I agree with Batty, I would bet that it is the sock/ debris clogging up.... The one on my 65 gs was rotten and cruddy with gas snot and other assorted junk.... what I do is take the sock off and just put a big fuel filter inline and keep it changed... that eliminates that problem.... The less restrictions that you have in a fuel line the better off you are... especially if the restriction is some where that you cant get to,,,, like inside the tank....i use the big filter like is on a farm tractor,,, or one of the old holley can type that goes on a gasoline semi truck...

 

Problem solved! It was combination of things. My tank was pushed up slightly under where the sender sat. When I took the sender out, I saw that there were abrasion marks on the bottom of the tank. I pushed on it and it popped. I tapped it a bunch to make sure that it would not pop back in. I bet the sock was collecting debris and or itself and bunching up in-between the sender pipe and the bottom of tank. The car is running now thanks to you guys. It took knowledgeable Buick fans to work this one out.
Now back to the new Q-jet I put in, the idle circuit seems a little rough...
Thanks!

 

Glad to hear the news!

Devon

 

i ran without a fuel return from the pump to the tank had major vapor lock problems. i had ran with a 2 bbl the summer before without problems switched to a q jet and it couldn't run with out the return.