Hard Start On Cooled Engine

[BlackCoffee]

When three things combine, the Expo has a hard start for about 8 seconds. It appears fuel starved. If I bring the engine up to temperature and drive to work (20 minutes), and let the engine cool for 90 minutes to 2 hours, the engines cools to about 125-130F. This causes a hard start. It is the only combination of events that causes this to occur. Starting cold and then restarting before reaching temperature is fine. Turning off hot and restarting is fine. Turning off hot and allowing to cool to somewhere below 70F is fine. It is only the 90-120 minute window that results in the engine being somewhere around 125F that creates the hard start. After the first start, everything works fine. Except for this, it always starts on the first crank.

I have replaced everything related to fuel, evap, and injectors, except the fuel inertial shutoff switch. I just put in a new fuel pump (didn't mind since I have 150K on the old one), and get fuel pressure at 35psi solid. Same symptoms as before. Any ideas? Now outside air temp sensor. 10K ago. This problem has been around since the Expedition was new.

2003 Eddie Bauer, 5.4L, 260K, Excellent Shape, rebuild engine and transmission.


Any ideas or TSBs?

 

[Hamfisted]

You are the original owner, and it's been doing this since it was new ?
Did you replace the whole fuel pump assembly? Or just the electric fuel pump itself? Just wondering, because the line check valve is part of the whole assembly.
See if the rail is holding 25-35 psi of fuel pressure after you turn the key off. If it drops to zero you have a bad check valve at the fuel pump, or leaky injector. Also if you are in the hard start window try turning the key to the ON position a few times before actually trying to start it. This will cycle the fuel pump each time and build up the line pressure before actually starting the motor.

 

[BlackCoffee]

Yes, I am the original owner and I would say it has been happening since it was new. I don't think it was always this consistent, but I do remember over the years that it would hard start a lot. I am now able to reliably duplicate the problem.

I did change the entire pump with a Motorcraft replacement and it does hold pressure on the rail at 35 psi. With the pump replacement, I don't think it is the check value. I also question a leaking injector because it is fine if the engine sits long enough to cool complete down. I will try to check the pressure when conditions are right for the problem and see if I can nail that down more.

Thanks,