have a 96 f150 with dual tanks when sits for a while will have to turn on and wait couple minutes for what seems to be fuel pump to catch up does it on both tanks also sometimes when driving will turn off and have to let set with key on couple minutes seems like may be vapor lock but have no idea any suggestions

 

I've never heard of that kind of problem before but vapor lock is very rare with in tank fuel pumps that "push" the fuel towards the engine. I wonder if a restricted fuel filter could cause that problem, maybe your not getting enough fuel volume to the engine??

-Jon

 

or a leak bleeding it down when sitting

 

yeah, it's a fuel pressure issue, rather than vapor lock. You really need to check the fuel pressure both when it's running, and after you turn it off. You want to see how fast the pressure bleeds down after the key is turned off. A volume test may be necessary as well, but read the pressure first.

Take care,
~Chris

 

What tool or gauge is needed to check fuel pressure how do I tap into it while it's running

 

This thread died 12 years ago...............

You need a fuel pressure gauge, and it connects to a Schrader valve on the fuel rail.

 

The answer depends on the truck, and we have NO IDEA which one you have. Click this, read the whole caption, and follow its suggestions:



Vapor lock doesn't happen on EFIs.

 

have you checked the fuel pump relay? leaky injectors? or air getting into the lines, these are my thoughts.