03 4.6L Cranks but won't start (Sometimes)...

[David15]

Hello everyone,

I've been having the issue with my expedition for awhile now and really need to get it fixed. However it is an issue from hell. I cannot figure out what is wrong with my car.

Here's the situation, the car runs great when it runs! However sometimes it leaves me stranded randomly. I can drive to the store and when i come out to drive home it will crank but won't start. I'll end up getting someone to pick me up and then come back an hour or two later and it'll start right up no problem. then the next day i'll be driving around all day stopping at starting the engine and it'll be fine. But then other days it won't start again.

So far i have replaced the following on the truck:
Crank shaft sensor
Cam shaft sensor
Fuel pump
PATS halo system in the ignition
and Finally the ECM along with new keys and fobs.

After changing the halo system I thought it fixed the problem... even done a 1400 mile road trip over a week or stop start the engine and didnt have one single problem with it not starting. However, a couple days after we got back the same problem happened again. (Talk about frustrating). After this happen I decided to buy a new ECM. However that failed to fix my problem.

If anybody knows anything about this, please let me know! Or if there are any suggestion on what i should try out to figure out the problem that would be great. Thanks, David.

 

[jt_armstrong]

Next time it happens try check if you have any pressure on the fuel rail. A common fault on these models is the fuel pump relay which is soldered to the fuse box circuit board. Since you have changed the pump and if you have no fuel pressure then you can be fairly confident that the relay is your issue. 15 mins with a soldering iron will sort the problem. Replacements relays are readily available for about $5.

Sent from my SM-G920T using Tapatalk

 

[Bedrck47]

Sounds like your throwing parts into it with the hopes you finally get lucky.

As stated above.

I would suggest that you pull the fuse block and check the circuit board using a magnifying glass and look for any signs of burn marks around the fuel pump relay.

Its a well know issue on the 03 fuse blocks

 

[David15]

Well when i turn the ignition on i hear the fuel pump turn on and when i do eventually get it to start later on i can smell the un-burnt fuel from the exhaust. I have taken the fuse box out and have checked the circuit board out and everything seems fine. Removed everything and put them back in the same spot. So I don't think this is a fuel related problem. I think the issue is a no spark situation. Anyone know the best way to check a no spark condition? Or any known causes behind a no spark condition?

Thanks for the replies guys.

 

[Skauber]

Smell of unburnt fuel could be lack of spark or running rich from stuck open injectors. Does your fuel pressure stay fairly constant? Or does it drop off quickly?