02 Expedition starts but won't stay running

contento · 02-05-2008, 07:38 AM

The truck turns over fine but won't idle at all. It dies almost immediately after firing over. If I throttle it over and over and can sometimes keep it running but barely and only for a few seconds at best.

What I've checked:

- alternator: tests fine
- battery: replaced
- fuel pump: I disconnected the fuel lines at the tank and got plenty of pressure out of the pump with the key on
-throttle body: clean and the linkage moves freely. I used some carb/choke cleaner into the throttle body to try to keep it running, but no luck.

Until this, the truck was running fine.

Thanks all!

jonmark1985 · 02-05-2008, 07:46 AM

How is the spark?

Flyingjackal456 · 02-05-2008, 08:57 AM

What about The Idle Air Control valve? grab your Throttle body cleaner, and remove and clecn the IAC, and let it dry, then put it back. Checking your spark plugs wouldn't hurt either.

ABE · 02-05-2008, 09:08 AM

Hi contento, welcome to the forum.

Sounds similar to this thread:
http://www.ford-forums.com/ford-expe...-cuts-off.html
The engine is a 4.6 and the fuel pump would stop operating after a few seconds and engine stalls. Re-starts and dies. Ignition is apparently OK. A new IAC was installed and engine fine for short time then problem re-occurred. Ignition OK and fuel pump is not being supplied power. Tank dropped and pump checked, when power supplied to pump the output is good. The fuel pump relay was replaced with no change. The point at which no power was detectable in the fuel pump circuit was not determined. No resolution to date.

Good luck.

contento · 02-05-2008, 10:01 AM

Thanks all! I cracked the throttle a bit manually after startup but it still dies, which should eliminate the IAC. I've also had the battery out for like an hour, so the PCM would have reset if that were the problem.

I read these in that thread:
1. the EGR valve. It is supposed to be closed when engine is cold or idled, but if it is stuck open there would be a very lean mixture Could be I guess?
2. the coolant temperature sensor: dont know where to find this. it said "front of the manifold by the thermostat" but I need more precise locations.

ABE · 02-05-2008, 10:47 AM

The coolant temperature sensor on the 4.6 is mounted vertically near the thermostat housing. It will have a plastic electrical connector with 2 wires.

ABE · 02-05-2008, 10:51 AM

Be careful with throttle body cleaner on the throttle body of your engine. Ford has put a coating on some (my 2000 Taurus as an example) and prohibit use of the cleaners.

contento · 02-06-2008, 03:58 AM

ok, so I can't find the fuel relay. The owners manual calls it out as R303 but doesn't show it in the passenger compartment fuse block. No suprise there. However, I can't for the life of me find another set of relays/fuses in a standard black box under the hood. Can someone tell me where the heck the rest of the relays are please@!

ABE · 02-06-2008, 11:25 AM

The 2002 Expedition owner's manual identifies relay 301 for the fuel pump located in the Power Distribution Box (PDB) in the engine compartment. It is on driver's side near fender on the firewall side of the air intake hose.

Page 193 of the owner's manual shows the location of the PDB and the fuse/relay locations. Fuse #10 is 15A and identified as fuel pump only, fuse #18 is 15A and identifies the fuel pump along with a number of other components. Relay is #301.

When checking these components, make sure there is good electrical contact, sometimes bad contacts can do strange things.

Hope this helps.

contento · 02-06-2008, 12:13 PM

SORRY...I wrote '02 but it's an '03.

The owners manual says the fuel pump relay is R303