My sisters 97 Explorer 5L fuel injected up and quits running. Truck wouldn't start until gas was added to the fuel tank.. I think what is happening is no air is being let into the tank and a vacuum is forming. The last time this happened I pushed in the Shrader valve on the furl system and no fuel came out. I thought this was caused by a failing fuel pump but when the gas cap is removed and air is let into the tank , the truck would start and lots of gas came out the Shrader valve. I had a similiar problem with an old Dodge truck I used to own. What would stop air from getting into the tank to prevent a vacuum from forming. Thanks for all your help.

 

Vent valve , either stuck or filter on valve plugged.

 

Easy test would be to leave the cap cracked a bit.. On a stall no start, do you hear the pump running?

 

Thanks I will check it.

 

I don't hear the pump running. When I push in the shrader (sic) valve on the fuel line, gas spurts out so it has pressure,

 

The fuel pump run is ‘timed’ on a key cycle to ON/RUN, only on a few seconds active , just releasing the pressure won’t run the pump. On a no start, if you cycle the key, you should be able to hear the pump run, either from the underside, or listening in the fill neck.. It would be best to put a gauge on the schrader and test for spec pressure and volume