2000 Expedition, 4.6, 4wd, 73,000 miles

Truck wont start sometimes after being driven for about 20 mins and then left off for about 20 mins, normal crank, no fuel at engine, fuel pump not coming on, get it towed once off tow truck starts right up as if nothing happened. Reproduced problem at home, only this time there was fuel at engine and could hear pump come on, would start but die immediately, left it for about an hour went to start same as before where there was no fuel and pump didnt come on, cycled key 4-5x times and started right up. reproduced again at home (a different day) checked for power at pump, when starts power at pump =13.5 volts when not starting power at pump = 9 volts. All relays/fuses are good, inertia switch is good, battery is good, No check engine light. Any suggestions????

 

Have you changed the fuel filter?

 

Fuel filters getting changed this weekend, was going to change filter w/ the pump but I'm not sure if its the pump or something else.....

 

does it have any kind of problems while your driving when it does start and run? are you using the factory key? security system problem maybe.

 

One scenerial -

As soon as the pressure bleeds down , - she starts!! The rails over -pressurized. ~Check the regulator

BTW-The same thing happens when you crank the engine more than 5 seconds. - Shuts the injectors down. It's a fail-safe for the cats.

 

The fuel filter wold be my first guess. You say all the relays are good which would be my second guess

I had the same symptoms (with a lot more miles though - 160000) and it turned out to be the fuel pump. Man I went through everything because I could not believe the pump could be good one time and bad the next.

Good luck with your problem.

 

No driveability issues at all..original key, happens with both of them..I thought the same about the security system but no theft light and i didnt think the security would "reset" itself?

 

Do you know how to check the pressure? If not, just take it in and tell the dealership what it's doing.

 

I know how to check the pressure, just gotta wait for my friend who has a gauge to bring it by.

 

I would do that. I'm not sure where the relay is on the 2000, they changed the fuse blocks around quite a bit from model years. The relays are listed in that little booklet that comes in the glove-box when you purchased the vehicle. Anyway, you should be able to swap the fuel pump relay with the horn relay to determine whether that is the problem or not. Make sure they are the same, they are on my model.

 

Did you check the battery voltage under load (while engine not running)?