F150 S/C 4x4 XTR 4.6 engine About 6 months ago my truck started to die on me ater going through an intersection. I thought fuel pump issues right away, but I changed the filter before anything. When I had the old one off I wanted to see how dirty it was so I blew into it and I could barely get any air through it. (I have since started buying fuel elsewhere) So put new one on and no issues. Truck seemed to run fine till about 4 months ago. I went out in the morning to head to work, and truck wouldn't start. I was nearly late so I took my wife's van. After work my truck started right up. It was starting intermitantly and sometimes I had to turn the key back and forth a couple of times, but usually got it running. Other times I could get it going by bleeding the fuel pressure of at the fuel rail and I was thinking fuel pump is on it's way out the door. I changed the fuel pump and filter last week. Truck started right away after that. I let it run for a few minutes the turned it off. Now I can't get it going again. I have taken the tank off again and it is on my garage floor. My brother broke the rear electrical connector, so I ordered a new on today. But now that I have the tank off again, can anybody point me in the right direction or give me some advice on the next step?? Thanx in advance!!

 

I tested the relay according to Haynes manual, fuses all seem to be good. I am gonna clean the IAC valve and the Intake tubes while waiting for a part to come in. What else might I check/test and/or clean while down? thanx travis

 

Maf

 

Throttle body

 

After changing the pigtail for the rear of the tank I got it back up and secured, added a bit more fuel and presto......fired right up. I drove around the block, then parked back in the driveway. 10 minutes later it wouldn't start again. I checked for fuel at the rail but there was nothing coming out. I listened for the pump when I got my daughter to turn the key but there was nothing. So now there is no power to the pump. I am a little frustrated now. and I need to walk away for a while. Anyone have any ideas?? thanks trav

 

For some reason it fired right up after work today. I was surprised again, so I tried turning it off and starting about 10 times. Would a relay fail some of the time allowing the pump to only work some times?

 

A relay can stick part time, but I can't say if that is what your problem is or not.

 

I tried a new relay and the old was was a little warm when I removed it. I could here the pump run for a second after turning the key with my head down beside the tank after I had frirst changed the pump. Then when it was warm and not starting I could not here the pump at all after turning the key. It was only $18 so I got one on the way home form work. I have been starting it over and over for the last couple hours trying to replicate the problem but it only starts now.

 

Yea, -if they're the least bit warm, -it's bad and must be replaced. They only warm out when the gate sticks.

 

Now yesterday morning I got nothing. Wouldn't start all day for me. Then this morning I was gonna pull the relay for fun, but I turned the key and heard the pump so it fired up like nothing. This has got me stumped and I might have to take it in. Any more Ideas out there?

 

Sounds like it's shorting out somewhere. You have to track it down. Make sure the fuse block under the dash isn't loose. That can cause intermittent problems.

 

Try this to determine the pump at fault. Turn the key to charge the fuel lines. If you don't here the pump prime, leave the key in run, slide under the tank and tap it with a hammer. If the pump starts, it's at fault. You'll hear it.

 

So I am %99.9 sure I found the trouble. After removing all of the shrouds and covers and panels under the steering wheel to look for shorts, or loose wires, I noticed one loose wire today. Which, after looing a little closer turned into two broken wires and one of them allows the pump to kick in when the key is turned to on position. I replaced the pump because I figured that there was very little pressure a lot of times and thought relieving the pressure at the fuel rail might help. Turns out I didn't need to, one more lesson learned. Thank you jbrew for making me chase down the trouble a little further. I knew in the back of my mind that it might be a short or electrical-related, but they can be a real pain to find so I really didn't want to go that route. Travis

 

So it was the harness leading to the P.A.T.S.(passive anti-theft system)After trying to order just the pigtail and recieving the wrong one, I got the whole new tranceiver for $105. It took 5 minutes to change out. Too bad the pins and sockets on these things are too small to replace the wiring, but like I mentioned before one more lesson learned. Now I know a little more about this little thing, and where to look next time this happens and have a spare fuel pump on top. Likely caused by excessive tilting of the steering wheel. Not unlike some troubles I had had with the multi function switch plug and non working brake/tail lights. Hope this experience may help someone else.
Travis.

 

Great job guy!