I have a 2003 Explorer sport trac with a 4.0 liter V6 which is very hard to start. The truck only has 69k miles! It usually takes about 3 to 4 trys for the engine to start. Also, In the last 3 months the engine has just shut-off while driving 2 times. The past couple weeks the problem has got worst, any help would be appreciated. Thanks.

Phil

 

Connect a fuel gauge to the rail and check the pressure, seems you may not be priming.

Replace the FP relay......

 

Has the "Check Engine" light been tripped?

 

there is no engine check light. Also, the hard engine start problem is worst when engine is cold.

 

could a bad IAC valve or DPFE sensor cause this problem?

 

Yes, but so could a bunch of other items. If you want to shotgun those two parts, you're welcome to. If they don't fix it you could also shotgun the Engine Coolant Temperature (ECT) sensor, the fuel filter, and the fuel pump.

Cycle the key a few times between Off and Run, pausing in the Off position about 3-5 seconds each time, then try to start the engine. If it fires quickly after the cycling, this would suggest the fuel pressure is low. The fuel pressure gauge suggestion above is a more sure-fire way, but not everyone wants to spend $40 on the gauge. You could start by replacing the fuel filter, but chances are good the fuel pump is weak.

-Rod

 

Thank you Rod. I cycled the key 3 or 4 times and on the 5th turn the truck started right up. It does seem the problem is in the fuel delivery system. I'll change the filter first...I'm sure it's due any ways. If the problem is still there I'll check out the fuel pump. Do you think it could be the fuel pump relay? Well, again thank you very much.

 

I doubt the fuel pump relay is the issue. You can check for voltage on the pump side of the fuel pump inertia cutoff switch. If you always have battery voltage or close to it at the switch but you still don't get quick starts unless you cycle the key a few times, that would pretty much rule out the relay or a bad connection, unless the bad connection is at the fuel pump in which case you need to drop the tank anyway.

-Rod