2004 Expy 5.4L Dying

[painoz]

Hope I get some insight on where to go from here.

Never had a problem with our Expy until 2 weeks ago was on the highway going up slight incline, increased throttle and no response and engine started to die. Worked the throttle a little and before it completely died it started going again. It has happened 5 more times since with each time the engine completing dying (i.e. losing power steering and brakes). When this happens CEL comes on and I still have battery power. It will restart and run with no problems after it sits for a minute or two. Took it to have the codes pulled......and no codes.

I have checked all the wires in the engine bay. Nothing exposed or frayed. I have cleaned everything on the battery and surrounding components as there was some corrosion. I can hear the fuel pump prime when in the accessory key position, so I think it is something electrical. It also seems to happen only when the AC is on.

I have read about the fuse box problem. I have read about a fuel pump relay problem. I have a new fuel pump relay and fuel filter that I am waiting to put in, but I really think it is something electrical or ignition related.

My question is where to go from here. Your opinions are greatly appreciated.

TIA

Nate

 

[Hamfisted]

How old is the fuel filter ?
As far as the fusebox issue:
If it's the original fusebox take a look at the PCM relay (top right corner of fusebox...) and inspect it for evidence of overheat, like melted plastic around the terminals. Those top three rectangular relays in the fusebox are interchangeable, so if you do see melted plastic you can swap with one of the other relays till you can buy a new one (Autozone, dealer, or online...). If you see melted plastic on the relay, in the end you'll end up replacing the fusebox to fix the route cause, which is the fuelpump's micro relay that's soldered onto the fusebox circuit board.
If the fuel filter is new, and you don't find evidence of relay overheat then start looking at the fuelpump in the tank itself for replacement. You can buy a cheap fuel pressure test gauge at any autoparts store or Harbor Freight, or online and test the fuel pressure at the fuel rail at different rpms. You are looking for a constant 50-60 psi of pressure throughout the rpm range.


-Mike

 

[painoz]

Mike,

Thanks for the feedback. The fuel filter has never been changed. Car has 110k on it. I will change that first, then look at the PCM relay. I appreciate your help.

Nate

 

[Hamfisted]

Yeah change that out for sure. A dirty filter causes the fuel pump to work harder and leads to lots of problems. Use Motorcraft or Purolator filters. Should be able to find them at a local autoparts store. Once you get the plastic cover off you release the fuel lines by pushing down on the blue buttons there on the fuel clips. It's up under the driver's seat next to the gas tank. No tool required.


-Mike

 

[onlyexilove]

I just recently had to go through this with my 2004 5.4L (about 1 week ago). It is actually the soldered fuel pump relay in the middle on the inside of the fuse block. They call it a non serviceable relay which basically means its soldered onto the board and the mechanic is not going to take the time to solder a new one. The relay ran me $17.99 shipped from ebay and I got it within a few days. It took me about an hour total to pull the fuse block and solder the new one on. Here is a link to a really good step by step of taking apart the fuse block to replace the relay and also a link to order the new relay. Hope this helps!!

Video: https://www.youtube.com/watch?v=JjnlWO4ciFg

Relay link: http://www.ebay.com/itm/NEW-Ford-Fue...-/271331387441

You can probably find the same relay on other sites with about the same amount in shipping. I bought 2 just in case.