Suburban sputtering problem Need advice

[GN ERGY]

My 81 GMC suburb runs fine untill I take it on the freeway and after about 15 minutes it starts surging and has no power. Then it finally dies. I have a glass fuel filter and it will be empty when this happens. I have checked all the fuel lines cause I thought I was getting air sucked in from a crack in a line somewhere. If I let the truck sit for a while it will start and run good up to 35 mph. This is the second time it has done this to me. I put a new fuel pump on the last time it did this and thought I had the problem solved. Is there some kind of fuel sock in the gas tank that could be causing this. Dont want to pull the 40 gal. tank down if that isn't the problem.

HELP

Tarey D.

Thanks guys

 

[The Radius Kid]

Sounds like vapor lock.How's your evap canister system working?

 

[1ARUNEM]

I will assume the truck has a manual fuel pump. It certainly could be bad although it is not old. If it is a manual pump, no sock in the tank..

First off though, I would take the fuel filter off and try to blow through it to see if it is restricted..

Goodluck..

 

[GN ERGY]

It's a mechanical fuel pump and I replaced it when this problem first happened. I have a see thru glass fuel filter that sits on top of the motor. When I have this problem the filter will be empty, no gas inside. Other wise I can see the gas flowing.
I'll have to check the canister out to see if that could be my problem. It did seem funny that when this problem was happening I could see air bubbles coming from the side of the filter that goes to the carb in to the gas side.
Now you got me thinking VAPOR lock.
Thanks guys, I'll let you know what I find out.
Tarey D.

 

[tjthorson]

Loosen the gas cap too? Might be a bad cap causing a vacuum?