Fuel starvation issue? Please help.

[natedogg]

I recently bought this 84 GMC cheap because it didn't run, needed a transmission and had been sitting awhile. Swapped in a used trans, new plugs, wires, rotor and cap. Fixed a few other things and started driving. Seem to run and drive great and then this problem showed up and has me stumped. Once the truck warms up and after a short drive it won't accelerate fast. It will speed up, but slowly. I put on a new fuel pump, fuel filter, carb base gasket and a different quadrajet that I had and didn't solve the problem. Also, I made sure the heat riser was fully open at full operating temp. Keep in mind that this truck is mostly original with a 305 and the ESC distributor still in place. However, all of the smog parts and converter are long gone. Any suggestions? Thanks for any and all help.

[cadillac_al]

When it starts running bad pull over and open your gas cap to see if there is vacuum in there. It could be a malfunctioning vent. If all the smog equipment is gone already then I would buy a Skip White distributor so you can have a normal vacuum advance.

[kwmech]

Cracked fuel lines on the top of the tanks and on the switching valve

[mongocanfly]

There also is a filter in the carb where the fuel line hooks up....That's where I found my problem once....it was a piece of Teflon tape floating around in that filter.....

[75C10]

I had a truck once that would run but wouldn't drive. No power. Exhaust filled with mouse nests.

[natedogg]

Thanks guys. I did put in a new fuel filter and that didn't help. Truck is a single tank and I'll check the lines on top of tank for cracks and check the exhaust for rats nest.

[Pontiac1976]

Since you checked the carb fuel filter did you make sure the truck does not have another aftermarket fuel filter on between tank fuel pump, Or could be timing off a little. check to make sure the dist. hold down not loose. OH when you change a fuel pump did you make sure you got the air out of the line. Because a air bubble moving around ( fuel pump to the carb ) when motor warm it will cut the fuel down make you crazy like not getting a full fuel bowl for the dam you higher rpm.

[natedogg]

There is no extra filter between pump and tank. When I put new pump on, I left line off the carb and cranked it over and watch gas shoot out. Distributor is tight and set correctly.

[Jake Wade]

There is a fuel pickup screen/sock in the fuel tank, perhaps its clogged.

Is the timing advancing as it should?

[truckin 79]

I would say it is electrical since you know you are getting gas. Check coil check control module

[natedogg]

Turns out it was the control module. Swapped in a used one I had laying around and truck runs great now.

[Palf70Step]

Glad to hear you got it figured out!