Two days ago my truck started to run like it was starving for fuel. Then today it got way worse. I started running like it was out of gas. Finally it died but I was able to restart it a couple of times and drive half a block to a block down the street. After a few restarts it finally refused to crank.

After having the truck towed home I started checking the easiest to identify fuel problems. Fuel pump fuse is good. Inertia switch is good. since I can hear the fuel pump turn on when i turn the key on I decided to check the fuel pressure. When the pump initially kicks on the pressure spikes to 85psi then drop rapidly to 45psi. After the initially pressure drop the fuel pressure continues to slowly drop. The truck will turn over but will not start or even act like it wants to start. After reading on this forum I removed and inspected the FPDM. The FPDM appears fine from the outside with no holes and very little corrosion.

So I'm seeking advise on what to try next. Is there an easy way to bypass the FPDM or and easy way to diagnose this as the problem? Could it be a weak fuel pump? Or is there something else I need to look into??

 

Did you try a new fuel filter?

 

Yes. I actually just replaced the fuel filter about 3 weeks ago.

 

Try this. I have no clue if this will work or not. Just a shot.

 

I pulled my fuel pump driver module and it appears to be in good condition, not hole or corrosion. The FPDM still appears to be sealed. I guess I'll just spend the money and replace it on the wild chance it might be the problem.

 

it could be the FPDM.....but to verify if the fuel pump is good you'll need a scan tool to see the fuel pressure....

 

^^^

 

whatever....

 

UPDATE--- Thus far I have hot wired the fuel pump and dead headed the fuel line up stream of the filter. The pump maintains 45psi like this. I have also replaced the FPDM. The truck still will not crank. However I can get it to fire and run for a few seconds with a couple squirts of starter fluid in the air intake. So now I am at a lose. seems as if the truck will fire and run with starter fluid then that should eliminate any electrical/ignition problems. Maybe I'm wrong on that though. I really wish Ford had left the shrader valve on the fuel rail in these 5.4l 3v engines....

 

Ok... Ignorant question time. Since this is a return fuel system then there should be now way there is air in the fuel rails cause a vapor locks type situation.. RIGHT?????

 

Forgot to mention that I am using an Autel/Autolink AL319 scanner. the fuel pressure on the scanner reads 38psi with ignition on and jumps to high 40's when the motor is turned over. I feel certian that my problem is NOT fuel related now..

 

It has to be fuel related, even if it's electrical. If it fires with starting fluid but not without, you aren't getting fuel to the cylinders.

 

I agree that it has to be fuel related. According to my scanner its getting proper fuel pressure. My test light reveals the injectors are getting pulsing voltage. It just doesnt make since to me at all.

 

Where is the fuel pressure sensor? What is between it and the injectors? Can you separate a line anywhere to verify that there really IS fuel pressure?

 

I tested the fuel pressure at the fuel filter and with my scanner reading from the sensor mounted on the fuel rail. There is no other place to disconnect the fuel line. I'm honestly starting to think it might be flooded now. I can smell gas from the exhaust.
Anyone wanna buy a good used F150 Super Crew FX4????? haha