I have acquired a 1994 F150 Flareside Mark III truck, has the 302 and auto trans, this thing is a hooptie. Its been parked since 2012 and had a plethora of problems. In the process of getting it running again after it sitting for years. I have just put a brand new rear tank, cleaned the front tank, two new sending units, new injectors, new fuel filter, and a handful of other new parts. I had fuel pressure before from the front tank, then I took the fuel rail off after discovering the rats have chewed the main engine harness. So new to me harness, and new injectors while i had it apart. Its all back together now and I do not have ANY fuel pressure in the rail now. I have tried both tanks and same story from either one. Pumps will kick on, but when i press the schrader valve in I have no fuel. I don't see any leaks anywhere along the frame or in the engine bay. the only part i have not changed yet is the regulator, but I should still see fuel at the rail right? I can pull the valve out and sometimes get a little fuel but its defiantly not getting enough pressure to run.

What are the things that would cause no pressure with brand new sending units, fuel filter, injectors, and clean tanks? ANYTHING HELPS! I'm pulling my hair out here!

I did order a new fuel pressure regulator, Ill try that when it comes in, but I am at a loss here.

Thank you!

 

I would put a gauge on before the fuel filter to see what you get. If it’s good, then you got a clog somewhere, either in filter or in line.

 

My money is on the fuel filter being plugged
Probably needs both tanks replaced and the lines flushed out
This is what can happen to the in tank pumps when the filter plugs up
This is what happened to my 04 when I did not notice the contamination in my front tank

 

Did you read this part from post #1?

Are the pumps turning on? You only replaced the sending units or the whole fuel delivery module? Did you have to replace the pigtail?

 

Put a gauge on it.

Jump the diagnostic connector. Turn key on.

Select tank.

Read gauge.

Fuel pressure Yes/No.

 

Are you sure the relay is good? Swap two of the cubes and see if it makes a difference. Next step is the tank selector switch. Also the front tank pump has a shuttle valve that are notorious for recirculating fuel (resulting in no pressure) to tank. I would pull regulator off the rail and then disconnect the front of fuel filter and spray carb or brake cleaner from regulator toward filter. It should clear any gunk if any. My dad has an '88 and it has a different pump setup where the in tank pumps just lift and an inline pump boosts to required pressure. Sometimes people swap parts around and unlike airplanes, there is no normal maintenance record book.

 

How did the relay go bad when the front pump was working before the pump was swapped and it seems like the pumps might still be turning on now.