Fuel pump relay

310

Asked by WHITE3281 Jul 19, 2017 at 11:02 AM about the 2004 Ford F-150 FX4 Ext. Cab 4WD

Question type: Maintenance & Repair

I believe my fuel pump relay is bad. Truck will crank
but won't start. Cannot hear pump running. I ran
power to the fuel pump and got it started so I
believe it's the fuel relay. I'm seeing that some
people are saying this year truck the fuel relay
switch is soldered into the fuse box and isn't
interchangeable. Is this true? Do I have any other
options than buying a new fuse box? New fuse box
costs 400 from the dealer

13 Answers

26,800

At the relay, unplug it, is terminal 30 hot, with engine cranking, It should be. If so, you can use jumper wire between terminal 30 and terminal 87, the fuel pump should run. If it runs that usually means the problem is on control side of relay, voltage and ground. The two top wires in diagram are voltage and both fuse protected. The voltage comes from pcm power relay. I'd want to check voltage and ground circuits for the relay before replacing. Just my opinion.

33 people found this helpful.
310

The 2004 relay is hard wired into the fuse box. So I cannot take it out. I spoke to another person who told me that if I have power on 32,33,34 with the key on, then my relay should be fine....I've changed the driver module and couldn't get it to start. I put power to the pump and got it to start. Cannot figure out what the issue is..

20 people found this helpful.
490

To start off with *WHITE3281* did not initially indicate what year his 150 was ? I have a 2002 model that began cranking and not starting on occasion and most recently will not start - it has no fuel pressure, relays K4 (fuel pump) and K163 PCM bench check O.K. and operate O.K. Both have power at pins 30 even with the key turned off - It is indicated elswhere that the wiring schematics are the same for the 1997/2003 models however the parts involved are physically located in different locations and are identified differently - On mine they are located in the fuse/relay box on the front LH fender - while *oilyspill*does give a great picture of the individual relay diagram - and guides one on how to jump directly to the pump --- I need a schematic that shows the whole fuel pump wiring system for a 2002 so I can see what else might be in the system --- For safety reasons I would suggest using an ohmeter to check the fuel pump for ohms /and or shorts before throwing any unfused voltage at it ---

12 people found this helpful.
490

ref." old guy " evidently I'm in exactly the same boat as you - I did exactly that and the ohms were well over 22k - then I hit it with 12 v. - obviously the pump still would not run - I did this @ the relay base - beforehand I field checked the relay and it worked just fine - remember even doing this there still is the possibility of corrosion buildup on either the hot side or the ground side so nothing is really accomplished here other than finding out if your circuit opened or not - Now I need to find someone younger than me to get er done ! Yes it would be nice to find a nice clearly legible electrical schematic of this circuit (Not a diagram)

7 people found this helpful.
490

2002 ford f150 fuel pump electrical schematic

26 people found this helpful.
100

mine do the same thing 2004 f150 my PCM relay switch was loose push back in started right up i might need to buy a new relay fuse box new for $400 .

10 people found this helpful.
490

ref: White 3281,oldeguy,oilyspill et all - These are all familiar posts for me and all have good information - my 2002 has done the same recently - FYI - In checking these things note there is a pressure relief valve on the back of fuel rail on my 4.6 L - it looks similar to a tire valve stem and can carefully be depressed to check for fuel pressure shortly after cranking - also on some year ? models there is an emergency crash switch located behind and above the RH passenger kick panel that sometimes trips if one gets bumped ! In checking my problem further I find my fuel pump circuit has 2.67K ohms resistance ( relay base to ground )and I'm on here trying to find out what is an acceptable reading ? - I suspect it should be less than 50 ohms ? Digging into this more I find that one of my fuel tank straps has let go and maybe with the tank hanging down a bit it has pulled a connection loose ?? 65 years ago it was a lot easier for me to crawl under vehicles and work on them !! Also FYI - I now find that on the subject of the fuel tank straps Ford had a Safety Recall Notice on them for some of the earlier models ( 2004 and older I believe ) -------- from 07/29/2011 they issued Safety Recall # 11V385000 & listed as Campaign # 11S21 -------- Has yours been done yet ? Cheers " another old guy "

4 people found this helpful.
60

Fuse box can be rebuilt with new relay around $ 150.00 ebay. had mine done, worked good 1 year warenty

6 people found this helpful.
10

I found posts in other forums about a harness junction that's under the truck, driver seat. Right there on the frame. Might want to take a multimeter and poke around, I don't remember the specifics of what was said but I remember it was relevant. My issue is I have gone through a couple fuel pumps recently and I just walked up to my truck and the fuel pump was running.. I was walking up to it to change the pump yet again but I should really figure out why it would be running on its own first..

1 people found this helpful.
30

I know this is old but did you ever figure out the problem with the 04 fuel pump?? My 08 just failed to start a couple days ago and I’ve changed fpdm and nothing. I can jump the wires at the fpdm and hear the pump but still won’t start. Zero fuel pressure. Any help would be appreciated.

3 people found this helpful.
30

Robs08nightmare2 I have an 07 and mine died going down the road a couple of months ago. Went against a shade mechanic's advice and bought one from the salvage yard. (identically numbered) Work for about two weeks and did the same again. Found out that it wasn't right box (guess whoever had the pickup before i bought it had to replace it before) I just bought the correct fuse box but it has to be programed to be able to start it again.

3 people found this helpful.
30

when the key loses its code it drops the voltage to the fuel pump to 7 volts, part of the theft system may also notice theft light flashing fast for 60 seconds then goes to a flash sequence of 1 and then count the flashes, that tells you the code, like 1 flash then 3 flashes is 13 1 flash then 6 flashes is 16 code 13 means the transponder in the key is not communicating a code 16 means PATS relay is bad....... I hope this helps somebody out there....... Jennifer Turner

3 people found this helpful.

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