Truck losing power

[AirSpeed]

Drove my 72 GMC 4x4 home from visiting my kids last week and on the way home I went to pass a Prius and almost didn't make it! As I floored the truck it seemed to lose power, like it was running out of gas, I let off the gas and it would gain power. The engine is a rebuilt 350 with a quadrajet and th350.
Any suggestions where to start looking?

[Longhorn 70]

Look at mister fuel filter inside the carb.
Remove the fuel line
Remove the fitting the line screws into
There is a small spring and the filter in there.
You should be able to blow through the small hole in the end of the filter. If not or it's difficult, there's the problem.

That's a start. You can also look at the fuel pump.

[ksshane]

I went to pass a Prius and almost didn't make it!

**FacePalm** But probably made that little Prius' day

[Biscuit240]

Originally Posted by AirSpeed

Drove my 72 GMC 4x4 home from visiting my kids last week and on the way home I went to pass a Prius and almost didn't make it! As I floored the truck it seemed to lose power, like it was running out of gas, I let off the gas and it would gain power. The engine is a rebuilt 350 with a quadrajet and th350.
Any suggestions where to start looking?

The float in most rebuilt quads is a plastic polymor that absorbs fuel then sinks to the bottom of the bowl and creates a rich condition that robs power. Nice huh? Replace it with a brass float.

Biscuit

[hamjet]

Also check the air filter.

[AirSpeed]

I was kidding about the Prius, that would have been truly humiliating! If that had happened I would have pulled over and pretended I was having a seizure!
Thanks for the suggestions all!

[Longhorn 70]

And here I made it a point to count the priuses I passed effortlessly on the way home from work, 9.

[zeldman]

Originally Posted by AirSpeed

I was kidding about the Prius, that would have been truly humiliating!

Yep, sure you were kidding.

And I agree with everyone else.... fuel filter. Also that polymor float can become saturated and swell up, and not working like it should. That is it will keep the needle and seat closed and not allow gas into the carb so then you will think you are running out of gas.

Good luck and let us know what you find.

[AirSpeed]

Originally Posted by zeldman

Yep, sure you were kidding.

And I agree with everyone else.... fuel filter. Also that polymor float can become saturated and swell up, and not working like it should. That is it will keep the needle and seat closed and not allow gas into the carb so then you will think you are running out of gas.

Good luck and let us know what you find.

I don't know if my carb has been rebuilt and has a new float but my fuel filter is clean as is the air filter. I truly don't want to pull the carb, specially since it's only about 10 degrees outside. I will check it out when I go south to see my kids again in a few days, it's a lot warmer where they live! (If I make it!)
Thanks again!