Truck Stop Running

[rwilliams1973]

Hello Fellow Members: I have a 71 Cheyenne that will not cooperate. It will run fine for about 25 min and afterwards the engine will choke out. Once the engine is cold again it will crank fine. I have changed the fuel pump. Any suggestions is appreciated.

[Hardesty454]

This is going to sound dumb but, have you changed the fuel filter? It may be sucking up what nots out of the tank and after a while clogging it up. Did the truck sit for any amount of time?

Also why are your specs? 350? electric choke? Type of carb etc. everything plays a factor otherwise we will be grabbing at straws to give you an answer.

[Keating121]

I don't have a lot of truck carb experience, but I've done MX my whole life. If its loading up and getting too much fuel I would look to the carb floats not seating and shutting off fuel into the manifold.

[SS Tim]

Might want to verify the fuel system is venting properly. 71 trucks under 6K max GVW had a ESC fuel vapor emission control.
Best place to start is with the factory service manual, section 8. Then you can see what you have and what might have been hacked and wacked over the years. There is a link in my signature below to downloadable copies.

Without background and vehicle specifc information its hard to make more than a guess.

[rwilliams1973]

Fellow Web Members: Thank you for the quick response. I have changed the filter. I have been ponder the control issue. Will look at that as well as the carb float when the sun comes back up. Thanks for all the tips.

[68gmsee]

-Does it run the same amount of time every time and then die or did it do it one time?

If that's the case, there's not enough fuel in the bowl to run an engine for 25 minutes without having to be replenished by the fuel pump so it could be restricted fuel line, defective fuel pump or clogged sock filter in gas tank.

A fuel pump should be able to pump 1 pint of fuel in to a plastic container in less than 30 seconds. Test it by disconnecting the distributor to coil wire remove the fuel line to the carb and have someone crank it while you monitor.

A test you can do to eliminate the restricted fuel tank filter issue is by buying a 2 foot section of fuel hose the same size as the one going to the fuel pump from the tank. Buy some good, fresh gas in a one gallon container and place it under the truck. Remove the fuel hose going to the fuel pump from the tank and replacing with the 2 foot section of hose and place in the gallon container.

[jhwkns]

Is the tank vented? Do you have a charcoal canister under the hood?

[rwilliams1973]

Originally Posted by 68gmsee

-Does it run the same amount of time every time and then die or did it do it one time?

If that's the case, there's not enough fuel in the bowl to run an engine for 25 minutes without having to be replenished by the fuel pump so it could be restricted fuel line, defective fuel pump or clogged sock filter in gas tank.

A fuel pump should be able to pump 1 pint of fuel in to a plastic container in less than 30 seconds. Test it by disconnecting the distributor to coil wire remove the fuel line to the carb and have someone crank it while you monitor.

A test you can do to eliminate the restricted fuel tank filter issue is by buying a 2 foot section of fuel hose the same size as the one going to the fuel pump from the tank. Buy some good, fresh gas in a one gallon container and place it under the truck. Remove the fuel hose going to the fuel pump from the tank and replacing with the 2 foot section of hose and place in the gallon container.

Hello 69gmsee: It runs the same amount of time, every time. Today when I turned the AC on it really kick over and died. I will be trying the gallon of fuel to pump to ascertain the sock clog issue/defective fuel pump. Thanks a million

[heyjoe]

Originally Posted by SS Tim

Might want to verify the fuel system is venting properly.

x2! I've had this exact same issue with an off-topic vehicle. The car would die after running a certain period of time. After chasing my tail thinking it was an ignition problem (late '70s ford duraspark box), the actual culprit was a clogged fuel venting system. I disconnected the vapor hose at the tank and never had the problem again.

[rwilliams1973]

Heyjoe, thanks for the response. i have also been chasing my tail on this issue for some time now. Once I have the solution I will post it hoping to save some other poor soul.

[heyjoe]

Originally Posted by rwilliams1973

Heyjoe, thanks for the response. i have also been chasing my tail on this issue for some time now. Once I have the solution I will post it hoping to save some other poor soul.

Please do! Too many times threads just fade away... we never hear what the solution actually was.
We poor souls are grateful for any saving we can get.