May sound like a dumb question but I'm just trying to convince myself that it's actually a pump problem. Well I test pressure koeo I get about 3psi and if I keep cycling it I can get it to 15psi but it will lose it within a minute. With engine running I get maximum of 30 and at idle it'll drop out to about 15psi once in a wile and barely run. There is no fuel back filling into the other tank or leaking anywhere so pump would be the issue correct. Also this truck is a 94 f150 4x4 5.8
PS would a pump from a 93 straight 6 truck work?

 

Check the vac line to the regulator for a fuel smell could be a faulty regulator.
Also try pinching off the return line and see what the pressure does.

 

Its not the regulator and with return pinched it barely gets any more pressure

 

I'd assume the pump.
Other than a kinked line or plugged filter, it would likely be the pump. Does the other pump work properly ?
About 93 1/2 they changed the 4.9 to run at 30 to 45 psi, previous to that they ran at 45 to 60.
Have never found a definitive answer on whether that pressure setting is controlled at the pump or regulator though, so the 4.9 pump is a crapshoot.

 

Ok thank you very much ... I guess this weekend I'll be doing the pump on it. Sence I have been wanting to put my spare less rusty and beat up bed on anyways I'll just pull the bed to do it. May be a good time to put my gooseneck hitch on also.