I have a problem with my 90 f150 sc 4*4 with a 5.0 and AOD. When the weather is really hot and it has been undere load for a while, the fuel pressure drops to nothing and it stops running on the current tank setting. I can swith tanks and continue for a while then it happens again and I continue the cycle of swithching tanks while the run times for each get progressively shorter until it stops altogether and I have to let it sit for some 30-45 minutes until I can continue again. The run time is short though before it happens again. I hooked up the pumps directly through the ADL ground wire and observed that the pumps make the typical noise but the pressure does not build up.

The pressure and regulator check out good when cold and this problem only happens during the hot summer months. I replaced the fuel filter and it helped only slightly. Has anyone had this type of problem? It seems really odd to me. Thanks.

Ramon Mendoza

 

Two suggestions, both of which are wild guesses.
Have you taken the pumps out of the tanks to see if the filter screens are getting clogged?
And have you tried running 12v to the pumps through a new wire directly from the battery?
Maybe the wiring's getting hot and dropping the voltage?
Like I said just wild guesses, peculiar problem though, especially since it happens to both tanks.

------------------
1999 Lariat Super Cab, S.B. 5.4L, 3.55 LS
and everything but the leaky slider window.
Bright red w/ gold 2-tone, Leather Captain's Chairs
Mods: Duraliner bedliner, Bugflector II, Hide-a-hooks.
& a leeetle chrome tip on the exhaust.

 

Thanks Indyfan. I'll look into checking for a voltage drop at the pumps. What I think I'll do is hard wire a voltmeter to the pump harnesses as close to them as possible. I'll post a result later. Looks like another scorcher today. I'm hoping to avoid removing the pumps themselves.