I have a 87 Ford F-150 with a 4.9L it has dual tanks, The problem is it won't start. I've replaced the fuel filter, external fuel pump, and a fuel tank switching valve (thats what I was told it is called, its a black fuel resevoir bolted to the frame, it doesn't have a motor, it has four lines going in and two going out) Anyway, I have replaced those three things and it still doesn't start, I know the fuel pumps work because the fuel will get to the switching valve. However when I unplug the fuel line after the switching valve no fuel comes out just a couple drops. I really have no other idea, I even tried the fuel shut-off switch under the dash. Any help you could give me would really help. I'm in the military and this is my only piece of transpotation, the military doesn't get paid much so anything will help..

 

have you tested the intank pumps, these a notorious for causing problems, we just had to replace all 3 pumps on my dads 88 E150.

 

Well I know the fuel is getting to the switching valve and I can hear the fuel pumps turn on when I turn the key.

It kinda looks like this:
[fuel tank]--[fuel tank]--[switching valve]--[external pump]--[filter]--[engine]

well if that makes any sense... thats the setup
Any other cause for no fuel??

 

it's just not getting through the valve correct?. Have you unhooked the hose AT the valve to see if it shoots fuel? Also how noisy are the in tank pumps? You may be hearing the frame rail pump and not the in tanks.

 

Yes, I can hear both pumps the intank is really loud and the external pump is a small whine, after I unplug the fuel lines from the resevoir only a few drops come out... even when I crank the engine nothing comes out... when I unplug it I can hear the pressure leaving, but no fuel. When I pour gas into the throttle body it will run so I know I'm getting spark?? Any other ideas??????

 

Yes I've unplugged the fuel line before the switching valve and gas flows like a garden hose.

 

have you checked for pressure at the fuel rail?
If you don;t have pressure there, I would check for obstructions in the line from the filter to the engine and the valve to the filter. Here is another good question do you have spark?

 

Yes I have spark, yes there is pressure before and after the external pump, and I can blow air through the lines?? Anything else????

 

Exactly how much? Put a gauge on the fuel rail Schraeder valve. Check for spark & timing. Pull the codes.

 

have you checked the electrical wire connections to the battery. make sure these are connected