2003 EB stalling, 2wd, 5.4 - nightmare

[RichardH]

The biggest electrical issue the 2003/04 Expeditions have is the fuel pump relay connection in the passenger side box. If it we're me, I'd replace the whole positive cable, not just the terminal end. On a lot of these Expys, corrosion gets inside the cable. Replacement cables are available aftermarket, so no problem there. I also use those felt washers under my positive and negative cables. My battery stays clean as new on top.

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Great idea and I do believe the dealer replaced both battery cables, then 'built' the fusable link into it since they could not find a factory or aftermarket harness.

It's early here right now (dark out), but I'll take a picture later today. I asked the service adviser to point out their work. The work really looked top notch.

I was always suspect of the that harness when I would do under-the-hood inspection. Fluids, looking for anything funny.

 

[RichardH]

Not the best pic, but they did replace both negative and positive cables/terminals and rebuilt the fuse into the cable. It's actually a spade fuse which makes replacement a snap. I have a bag of fuses and relays after paying a shop to replace the passenger well fuse box, so I'm covered with backup. I also have spare headlight bulbs, turn signal bulbs in the glove box. Pretty sure I'm good to go now. Took it for an extended shakedown drive this morning before I hit the freeway later this week. I should probably figure out a way to cover/protect the fuse though... I'll make a small cover, or at least tape it over with electrical tape. I looked online there are inline spade fuses like these with a cover built into them. I wish they used one.

 

[RichardH]

Lol, thought of the rough opal gemstones I bought the other year in a small plastic box. Perfect fit.

Cut a slot in the sides and it will protect the fuse. As seen still accessible. Pretty sure the polycarbonate PC plastic will hold up. Also added silicone to the slots I cut. Should be water/weather resistant. All the other fuses have covers, why shouldn't this one?

I might invest down the line in putting a proper in-line fuse with cover like shown above but this will work for now.

 

[RichardH]

So even after the rebuilt harness, it stalled out on me on the freeway. I had a bit of a long drive, everything worked great. Driving back home, zero warning - died. Threw it into neutral and fired back up.

Very strange. I'm frustrated. I also have a P0401 - EGR CEL. I've replaced the pressure sensor, two small hoses that feed it (no kinks) and the EGR valve. I thought any one if not all would eliminate the EGR CEL. I also had my independent mechanic check the 2 holes in the rear of the intake - clear and zero blockage.

No symptoms before it dies. No battery lamp this time around either. Charge is good at battery. It accelerates well, idles well. Just dies. There was was slightly perceptible symptom after I got it restarted while I was rolling down the freeway. Under steady throttle speed was very slightly changing speed/hesitating, almost like it was starved for fuel. If the pump is going down, it does not make sense it would start straight back up though.

The dealer did a PCM update, did live readings during their test drives and all looked good. Of course it did not stall out on them...

CEL is on but I'll check for any new codes in the morning, other than P0401. I'm sure that's there.

Any other ideas on the stalling?

 

[Hamfisted]

Original fuse box ? Original fuel pump ? If it still has the original fuse box, those are definitely suspect. But the "no warning" stall out is a known symptom of bad fuel pump micro relay in the original fuse box. The replacement fuse boxes have upgraded heavier duty micro relays in them.


It's a plug and play replacement job. Takes about 30 minutes.

https://www.amazon.com/Ford-3L1Z-14A068-AA-BOX-ASY-FUSE/dp/B000NS2B38

 

[RichardH]

Original fuse box ? Original fuel pump ? If it still has the original fuse box, those are definitely suspect. But the "no warning" stall out is a known symptom of bad fuel pump micro relay in the original fuse box. The replacement fuse boxes have upgraded heavier duty micro relays in them.


It's a plug and play replacement job. Takes about 30 minutes.

https://www.amazon.com/Ford-3L1Z-14A068-AA-BOX-ASY-FUSE/dp/B000NS2B38

Thank you. I'll read over it. I thought it could have been the alternator, but that would not explain the shut down since it can run off the battery for a bit.

It's a replacement fuse box already. I do believe it's a refurbished one. I am uncertain of the fuel pump status... newer or original.

I'll look into the micro relay. Even then, would a failed micro relay cause spontaneous shut down? I would think it would die slowly. Truck dies, all gauges in off position. Put into Neutral and fires right back up...

 

[Hamfisted]

Yes, when that fuel pump relay stops working, the engine dies with the loss of fuel pressure. Pull the top right relay ( PCM 203 ) and inspect it for signs of melted plastic, on the relay and on the socket itself. If you can, take a flashlight and see if you can read the part number on the actual fuel pump micro relay there buried in the middle of the fuse box. You might be able to read it through the gap there ( use your camera to take a close up picture of it, then read from the picture...). The upgraded fuel pump relay should be a Omron G8QN part number. The original fuel pump micro relays were part number F8VF and were the culprits of most of the early fuse box problems. Do you have a fuel pressure gauge kit ? If you do, take a reading of what your fuel pump is putting out at the fuel rail now. You should see 45-55 psi on a healthy fuel pump.

 

[RichardH]

I don't have a fuel pressure kit, but I appreciate all of the information.

I already took it to the dealer since the first repair is under warranty for this exact same problem. Code though was P0620, vs P0610 - same description though.

I have work to do, so unfortunately I have to rent an econobox car. I'm still going to do exactly what you said when I get the truck back in a few days. I was promised a diagnosis today. Could be Mon, Tues before it's ready best case scenario.

Are you referring to the small sliver of access to the PCB, green printed circuit board sort of visible to find the micro relay info?

 

[Hamfisted]

Yes. Did you say the alternator was new ? There's a test with a multimeter ( ohmmeter...) to do on the voltage regulator there in the alternator. I would hope the dealer tech would know to do regarding the P0620 code. But who knows what they'll do. But if it's the original alternator it may be time for a new one. The voltage regulator will go bad but it will still put out 14+ volts to the battery. It just won't communicate with the PCM, so it throws that 0620 code.


https://troubleshootmyvehicle.com/ford/4.6L-5.4L/ford-p0620-alternator-diagnostic-test-1

 

[RichardH]

Thanks. Interesting. I've read it could be the voltage regulator not 'talking' to the PCM. I brought this up to the service guy this morning. I asked him if the voltage regulator on these trucks were modular (or if you had to replace the whole alternator). He didn't know. That's concerning.

It does look like a newer alternator, good charge to battery, but as you said, it can still cause fault if regulator out of commission.

Sorry for another question, are the voltage regulators replaceable withing the alternator, or do I need a new alternator?