2003 Ford Expedition Random Starting

Tiny
NORTHGABOY
  • MEMBER
  • 2003 FORD EXPEDITION
  • 5.4L
  • V8
  • RWD
  • AUTOMATIC
  • 250,000 MILES
Sometimes it will not start and other times it starts right up and runs perfectly. Whenever it doesn't start, it cranks over like crazy, however it reads no fuel pressure at the rail. When it does start, it reads plenty of fuel pressure. The battery and connections have been cleaned thoroughly, the fuel filter and fuel pump both have been replaced. Also, the fuel pump relay has been replaced.

Could this be an electrical issue? Anyone have an idea of what it could be? I have heard that it could be the actual fuse box itself, but I'm not sure if that would fix it or not. I have inspected the circuit board inside of the fuse box and it does not seem to be burned anywhere, but I'm not sure.

Can someone please help?

Thanks in advance!
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Monday, March 14th, 2016 AT 6:08 AM

13 Replies

Tiny
NORTHGABOY
  • MEMBER
Also, by the way, I have checked and it is not giving any codes either.
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Monday, March 14th, 2016 AT 6:37 AM
Tiny
NORTHGABOY
  • MEMBER
And, this might be just coincidence, but it seems that when it does this that if I bang on the fuse box with the bottom of my fist 2-3 times; then it will start. I'm not sure if that has anything to do with it or not.
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Monday, March 14th, 2016 AT 6:46 AM
Tiny
HMAC300
  • EXPERT
The fuse box may not be making contact, try dielectric grease on prongs of relay and tweek a tad check for corrosion as well
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Monday, March 14th, 2016 AT 7:34 AM
Tiny
NORTHGABOY
  • MEMBER
Thanks for the answer. Actually, it was the PCM relay that was replaced as I am told that the fuel pump relay is built into the circuit board of the fuse box. I have noticed that the PCM relay seems to get pretty hot. Do I need to pull the PCM relay back out and apply dielectric grease on the prongs of that one? Is that the one you're talking about or should I apply it to all of them?
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Monday, March 14th, 2016 AT 8:12 AM
Tiny
HMAC300
  • EXPERT
No I forgot about this, this fuse box goes bad and most mechanics will put a new relay in for the fuel pump instead of replacing the fuse box it's the smart junction box that does this. Changing the pcm relay won't help
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Monday, March 14th, 2016 AT 8:16 AM
Tiny
NORTHGABOY
  • MEMBER
Ok. So, those are the classic symptoms of the fuel pump relay failing or starting to fail? Then it is not sending power to the fuel pump sometimes and sometimes it does? Then, that would explain why when it is just cranking and not starting, that I read no fuel pressure at all on the rail. Do the dealer mechanics replace the relays? I live in rural Northeast Georgia and am not sure of a mechanic to check with about this.
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Monday, March 14th, 2016 AT 8:32 AM
Tiny
HMAC300
  • EXPERT
No the dealer will charge about $1500 to fix this as it needs the smart junction box replaced. I can't find the tip from one of the mechanics wrote on here. But you can just jump the box by having one installed or getting a used one.
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Monday, March 14th, 2016 AT 9:48 AM
Tiny
NORTHGABOY
  • MEMBER
Ok. Thanks for your help. As I stated earlier as to my location, I guess I'll just have to buy the entire fuse box. So far, I have found one for $308.64. That's the cheapest so far, I don't know if I can find one any cheaper. I'm afraid of a used one as it might do the same thing. Have you replaced one before. Is it to complicated to DIY?
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Monday, March 14th, 2016 AT 12:17 PM
Tiny
HMAC300
  • EXPERT
I haven't run across one yet, but it seems to be a common thing on 2003-2006 it might be just plug in at back. The biggest thing is getting it out more than likely use dielectric grease on connections when you reassemble.
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Monday, March 14th, 2016 AT 1:18 PM
Tiny
NORTHGABOY
  • MEMBER
Dielectric grease the tabs of where the electrical connector ends will plug back into it? Any other places? Just making sure. Thanks.
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Monday, March 14th, 2016 AT 1:23 PM
Tiny
HMAC300
  • EXPERT
Nope just where they plug in
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Monday, March 14th, 2016 AT 3:59 PM
Tiny
NORTHGABOY
  • MEMBER
Ok. Also, I meant to ask as well, sometimes every now and then the display on the dash says "Check Charging System" & the battery light will come on sometimes as well. It hasn't been long since I've replaced the battery and Autozone checked the alternator and said that the alternator is fine and that it is charging. Could replacing the entire fuse box possibly cure this as well? Have you ran across this? Also, I have read that some people replaced the fusible link between the battery & the alternator and that it solved this problem for them. I'm just not sure? Do you have any ideas on this or how to check it? Thanks. Sorry for so many questions.
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Monday, March 14th, 2016 AT 5:58 PM
Tiny
HMAC300
  • EXPERT
Check the link and clean battery terminal ends first. Also if belt has more than 60,000 miles replace belt and tensioner as that is recommended replacement for both
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Tuesday, March 15th, 2016 AT 5:45 AM

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