Fuel Delivery Issues

SPORTEXP · March 12, 2011

Fuel Delivery Issues ***SOLVED***

I've done all the searching that I could possibly do on the subject here, but haven't seen any straight answers as to how the fuel delivery system works on this generation of Explorer. It starts off with stalling on the road resulting with a crank no start issue. After getting it to the shop I soon realize there is no return line going back to the tank. This is where I realized this is a whole new fuel delivery system. Checking the fuse I found it was blown. I put in a new one and found the plug going to the fuel pump and unplugged the pump from the harness, and hit the ignition switch again and popped the fuse again. So I dug around and followed the harness back to the right rear of the car and found it plugged into a box there, and this is where my journey ended for that. I went ahead and dropped the tank to explore this new kind of pump and how it is wired in, I also pulled the pump and wired it directly into the battery to make sure it still worked, and found that it does work. So this leads me back to this box below the RR taillight. What is it and how does it work? Can someone please enlighten me?? And if so PM me a wiring schematic on the system. I also tested the crash switch under the glove box to make sure it wasn't the problem, all was well with it too. Thanks

ncranchero · March 13, 2011

Which fuse is blowing, 26 or 29 in the Battery junction Box?

SPORTEXP · March 13, 2011

Looks like #26.

ncranchero · March 13, 2011

Ok. That circuit runs through the fuel pump relay, through the inertia switch and into the FPDM.

The box you speak of is the FPDM (Fuel Pump Driver Module [9D370] ). There will be an "Early 4.0L build that doesn't have it. Disregard that schematic.

Refer to Page 4 of the pdf.

SPORTEXP · March 13, 2011

So does this Fuel Pump Driver Module vary the pump speed to control the fuel pressure?

ncranchero · March 13, 2011

Exactly, from the ECM command.

BUT, swap the fuel pump relay with another one in the box and verify it's not just simply a bad relay. If not then you're looking at a FPDM or a short. You can unplug the FPDM to rule out the short.

Odd thing is that the 2003 doesn't show having this FPDM. The info is for a 2004. But your description fits the 2004. Wouldn't be the first time the Ford manual was wrong though!!

http://www.explorerforum.com/forums/showthread.php?t=237693

SPORTEXP · March 23, 2011

Thanks for all your help ncranchero. I have finished repairing the Explorer tonight. Your wiring diagrams were very useful in determining how to go about diagnosing this system.
First of all this Explorer was plagued with intermittent fuel delivery problems from the very beginning. All the dealership could figure was to change the fuel pump.
It was driven for a couple more years with this till it finally died for good then the local mechanic found a broken wire in the harness and run a jumper wire for the floating ground between the module and pump, as shown.
Now a year later it died again and now my turn at figuring out what's going on. First I find a blown fuse sometimes indicating a bad fuel pump, so I pulled the tank and removed the pump. I dried the gas off the pump and safely wired the pump to the battery to see if it works, and it did. This is where I learned of the fuel pump module. I used the wiring diagrams to bypass the module by jumping the White wire with the Pink and Black wire for the positive,and jumping the Black and Orange floating ground with the chassis ground Black wire. I reinstalled the fuel pump in the tank and then plugged it back in to the harness. Checking voltage with a meter at the jumper connections I got 12 volts at the jumper connection but still no fuel pump (the fuse didn't blow this time) this tells me that the fault lies in the harness. What I noticed in the schematic was that these wires were shielded, so all I could guess is that the positive wire was grounding against the shielding in the harness and blowing the fuse at first. To fix this I run another jumper straight to the pump connector and now all is good. :thumbsup:

ncranchero · March 23, 2011

Don't you just LOVE wiring?

Actually I do but it's hard to do over the internet! Glad you kicked it!

pjessmaster · March 24, 2011

Me too

I recently changed my fuel pump and the fuse and was working fine for a day, I did notice while it was running that the gas level gauge didn't really move. I didn't think much of it but the car suddenly died on me and doesn't want to turn on. I checked the fuse and its fine, does anybody think that the relay can be an issue here? I just thought it was weird because it was working fine then nothing.

*note: I just changed the relay and it didn't do anything. im lost.

SPORTEXP · March 24, 2011

pjessmaster said:
I recently changed my fuel pump and the fuse and was working fine for a day, I did notice while it was running that the gas level gauge didn't really move. I didn't think much of it but the car suddenly died on me and doesn't want to turn on. I checked the fuse and its fine, does anybody think that the relay can be an issue here? I just thought it was weird because it was working fine then nothing.

*note: I just changed the relay and it didn't do anything. im lost.

You need to see if you are getting power to the pump. Follow the previous tread and read it close I hope the info is there for you to understand (I'm not very good at describing things). A volt meter will help if you have one. Locate the fuel pump module and start there.

pjessmaster · March 24, 2011

oh okay I'll try that

pjessmaster · April 15, 2011

Ok. That circuit runs through the fuel pump relay, through the inertia switch and into the FPDM.

The box you speak of is the FPDM (Fuel Pump Driver Module [9D370] ). There will be an "Early 4.0L build that doesn't have it. Disregard that schematic.

Refer to Page 4 of the pdf.

do you guys have the link to the PDF?

ncranchero · April 15, 2011

No link. i can send you whatever you need though.

Diagnostics?
Schematic?

pjessmaster · April 15, 2011

I thing I have the issue to this answer but I don't see where this guy is looking. Thankx

I think I found my problem... corrosion in the 8 wire connector to the fuel pump. I tired smacking the tank a number of times with a rubber mallet, no luck. So I decided to check and see if the voltage is getting to the pump. I probed the pink and black wire..couldn't get a pin to stick in the wire when I tried to pierce it, so I shoved the pin all the way down it to the terminal block thinking that I would make good contact that way. Then I hooked up my meter to the pin and to ground. Thein I turned the key...looking for voltage on my meter, and car started!!! I was so focused on screen on my meter.... I never saw any voltage on my meter by the way. I didn't realize that for a half-second that it had started!

I ended up pulling that 8 pin connector apart and when it came apart a small cloud of white corrosion and red rust crumbs flew out. I cleaned up the connection with some corrosion cleaner and a small wire brush. It started repeatedly after that with no problem.

I would strongly reccomend to anyone having the same problems I had to check that connector. It's on the outside of the passenger side frame rail. It's under a cover that has two legs that slide into holes in the fraime and two plastic pins that hold it on. I think that there are additional connectors on top of the tank, but I think you would have to drop, or loosen the tank to get to those.

I may be confused in thinking that that it's the pink&black wire. Re-reading the wiring diagram that Ford gave me the pink & black does say (Fuel Pump Power), but there is a Red&Yellow wire that the illustration says is (Voltage supplied in Start & Run). So it's fair to say that I am still a little confused on which wire should have the 12v when..but my problem seems to be fixed!

Thanks to all for your help!

Spit

SPORTEXP · April 15, 2011

Thats a good start, the connector is located on the top side of the frame rail next to the gas tank about midway. Do you have a meter?

pjessmaster · April 16, 2011

yea I tried cleaning it but didn't do anything. I can hear the fuel pump turn on for a couple seconds when the key is in the "on" position, but then shuts off. If you have the wire diagram for the fuel system i would be very appreciative, thankx

SPORTEXP · April 16, 2011

When you replaced the pump. Ware did you get it from?

pjessmaster · April 16, 2011

autozone

pjessmaster · April 16, 2011

a month ago

SPORTEXP · April 16, 2011

I see, I don't want to anger you. When it comes to these types of issues it doesn't hurt to look into the original part from Ford. Silver State Ford seems to have the best prices on the net. Since you say you hear the pump wine for the first few seconds after turning the key on, this is normal and tells me you are getting power to the pump. The next question is do you have pressure from it? So far the only way I know of telling this is to hook it up to a scanner and see what it says. Also did you change the fuel filter?

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