Well, this is my second weekend of trying to get the fuel pump to work on my 05 F250 5.4 and still no luck. I am almost ready to give up and take it somewhere. I tried a new fuel modular first, no luck. Put in a new fuel pump, no luck. Jumped the fuel pump straight from the battery this morning to make sure it was working and yes it was. Checking for voltage I have around 10 at the fuel pump with the key off. First question is should I have voltage there with the key off. I have about 10 volts at the module. Should I have voltage at the fuel pump with the module wiring unhooked? I guess I am not understanding what this module is actually suppose to do. Is there a way to check this module to see if it is working? Guys, I have pestered you with questions last weekend and now this weekend hoping to find the problem. Thank you so much for the responses. It really helps.

 

I don't think you are going to have a chance unless you have a truck cd and all the drawings and are able to follow the cd to troubleshoot the system. Could be something simple and also could be a wire or connection that will take time to find..
Could you link to the orig thread? I might be able to send you a copy of the cd...


Dick

 

Well, this will tell you what you are dealing with here as far as smarts go.... what do you mean by link to the original? I will take any help I can get... Thank You!

 

Here's his original thread on the matter:

https://www.ford-trucks.com/forums/1...er-module.html

So to clarify: You've thrown lots of parts at the fuel system with no results.

What have you done to diagnose? Did you confirm lack of fuel pressure to the rail? I don't have the shop manual for your truck, but I would suggest first checking the inertia switch. This is from your owner's guide:

 

So far I have only installed a new pump, just the pump part not the whole thing. The fpdm module i took back because that of course didn't help. I took the inertia switch off and shook it to make the ball inside of it rattle, than reset the switch and the ball quit rattling. I took this to mean that the inertia switch was good. I think I am going to try by passing the switch tomorrow with a jumper wire and see if that makes a difference. Someone told me to just cut the wires and hook them together. I really don't want to do that so I am hoping I can does this with a wire. Any ideas and thank you again for the ideas to try.

 

Did you ever confirm that there was no pressure to the fuel rails?

Since the inertia switch is good I would then check to see if voltage is getting to the pump. If you can't find any good place to check you may have to pull the tank and check at the fuel pump harness. Ideally this should have been done before replacing the fuel pump, as you already had the tank down.

 

How did you test the inertia switch other than shaking it? If you have a DMM
(Digital Multi Meter) you can test the inertia switch in the ohms position. The
meter show show you less than 2 or 3 ohms for the switch.

Sean

 

All right, today I checked the inertia switch by checking the wires in and out of the switch, had power both sides. shook the switch to make it rattle, checked and of course had nothing. Reset it, shut off the ignition, waited for a few seconds, turned the key back on and had power out of both sides of the switch. I have power at the pump but my question here would be 4 prong hook up and I only have power out of one side or 2 holes. Should I have power on the other side of this hook up? I also have a 3 wire hook up that goes to what I am going to believe is the shut off for the inertia switch... maybe?... I am guessing here so I could be way off. Should I not have power there or not. It is in the middle of the fuel line coming out of the fuel pump so that is why I am saying this. I am really starting to run out of idea's and of course the frustration is really starting to set in after laying in the snow and ice for 2 weeks trying to figure out what is wrong. Thanks again for the responses and the idea's on what to try next. This site is awesome!!

 

So you have current passing through the inertia switch but(supposedly) none getting to the pump.

Unfortunately I don't have a wiring schematic for this model year truck, and that's what will be needed to have a better idea. I pay for the shop manual at ALLDATAdiy.com Leading Source of Factory Automotive Repair Information, and with the FTE discount it's quite reasonable at ~$30 for a five year membership.

That's your best source in my opinion for this information. Unfortunately other than this I'm at a loss without the information.

 

All right, here is what I can tell you.... the wire connection at the fuel pump i do have voltage. The female connector comes from the front of the truck and the male comes off the fuel pump. On one side of the female connection I have over 10 volts and the other side I have nothing. This is what throws me off because like I said, I bypassed everything yesterday with a hotwire straight from the battery and the pump worked. Should I have voltage off of both sides of this plug and I still don't understand what the 3 wire connector is on the gas line out of the fuel pump. Thanks so much for your help and Thanks for the website for the manual. I will check it out.

 

You can answer that one yourself, apply voltage to the pin that's dead and see what happens. My guess is that's your problem.

 

Fuel pump driver module gets a signal front the pcm. Its not a simple operation. Measuring voltages at the pump is not good as you could burn out things..If you give me an email address I can send you a drawing..


Dick

 

Maybe a dumb question, but have you checked all the fuses involved? And I mean w/ a meter, not by eye. Last year I had a similar problem w/ the truck in my sig, it turned out to be both the FPDM and a fuse - not sure which one though. I gave up and took it to the dealer - they had to get hotline help which had seen it before - that's when they started testing the fuses. They all LOOKED good, but one was bad. In my case it wouldn't even crank though, it sounds like your's cranks?

 

I will send it to you and thank you so much

 

Yes, it does crank. I checked all the fuses with my multi-meter for continuity. The bigger fuses in the engine compartment I wasn't sure how to check. I couldn't find any that dealt with the fuel pump other than the one that was 20 amp in the main fuse box.