Posted by Paul(in NY) [12.64.128.48] on Saturday, May 24, 2014 at 19:27:31 :
In Reply to: Vapor lock or bad fuel pump? posted by Tweety [142.161.200.205] on Saturday, May 24, 2014 at 18:36:39 :
Try this test. Run your truck on the road until you start to experience the problem, especially good if it shuts down. IMMEDIATELY go back to the fill cap and remove it, listening for a (air sucking sound). If you hear the air sucking sound ...good. Now dont tighten the fuel fill cap all the way, leave it loose and drive again....if problem is solved with the cap loose, you have found your problem.
The air vents in the cap are plugged. This creates a vacuum in the tank and no fuel flow. Removing the cap and hearing the air sucking sound is the vacuum in the tank being released. Running with the cap loose allows air to enter the tank and eliminates the vacuum.
The simple fix is a new VENTING gas cap.
Paul
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