Starting Problem with 1999 Ford Expedition


#1

I have a 1999 Ford Expedition with a 4.6L V8, 192K miles. Just replaced spark plugs, wires, and fuel filter. For the last 50K miles or so, it demonstrates the following starting problem: Engine cold - fires right up. Engine hot, turned off for a few minutes - fires right back up. Engine hot, turned off for approximately an hour - won’t fire right up (engine turns over same as always but takes several attempts to start). Any suggestions as to what is happening and how to repair it?


#2

I would check the cam/crank sensors. They are sensitive to heat and maybe getting heat soaked.


#3

Does the engine also stall out when hot?


#4

Engine does not stall when hot. It runs completely normal. It’s just that when it sits for an hour or so after it has reached normal operating temp, it won’t start right up like it does when it is cold or only been sitting for a few minutes. The engine turns over as normal but it won’t fire right off. It usually takes two or three attempts (because I don’t sit there with the starter engaged for more than a few seconds). After it starts up, it runs just fine (until it is turned off for an hour or so again).


#5

You could pull a plug and see if it’s sparking. Also, meter the fuel rail for pressure. This would lead you in the direction of what’s wrong.


#6

I’m up in the air about the crank sensor

Bad crank sensors can open up while hot, and that often causes the engine to stall


#7

On older cars with mechanical fuel pump, you might expect this to be vapor-lock, a fuel line overheating, being too close to an exhaust pipe, etc. Unlikely in a 1999 though. Unless there is some kind of unusual arrangement of the fuel lines and pumps coming from the tank to the fuel rail. hmmm … well, you could just start replacing stuff I suppose. But you’ll have less cash out of pocket probably if you can diagnose the cause, or at least narrow it down first. My guess is this is a spark problem. Ask your mechanic to test for spark next time this happens, or show you how to do the test yourself.


#8

This truck has coil on plug, I believe