Crank/no start condition on 2003 v8

[Explorer_PL]

Hello -

I am re-posting the questions since I got no responses whatsoever in the 3rd gen forum.

Helping a friend, 2003 Explorer 4.6 v8 AWD XLT. It always starts when cold, so he drives it to work, parks it for a day, and it starts after work, gets home, parks it for the night, ok again in the morning.
But if he were to start it after driving to work for a while, it will not.
He smells fuel, so I am thinking the fuel pump is OK, but no spark I suspect.
I want to use something (Forscan or handheld OBD scanner) to see the crankshaft signal and camshafts, maybe also fuel pressure and engine temp sensor.

Is that what you would check first ?
I looked in Forscan and my Innova 3160 but don't see any PID with crank sensor.

Open to any suggestions

Thanks in advance

 

[ThunderbirdSport]

What's the fuel pressure lookin' like when he tries a hot restart?

Beyond that I have no idea, and I'm not really so sure f/p would be the cause, anyway. Good luck

 

[michael loibl]

If it were a 15 years older explorer, I’d be betting on a bad ignition module. Those used to Cause a crank no start when the motor was physically hot, but would start up fine after a few hours of sitting parked. But that was a long time ago.

Is this the same 3rd gen 4.6 friend That was having the ignition coil trouble many months ago?

 

[Explorer_PL]

Yes, that the same truck, good memory Michael
He ended up replacing his cats since they were clogged.
I need to stop by with my laptop and Forscan to see what the fuel pressure is. On mine it oscillates around 38 psi.
I want to also get the reading from ECT sensor if it's working at all. I think it's hidden in the V valley so on easy access to swap it.

Someone on the web with same problem said that fuel pressure regulator may be bad. So after driving the fuel line is pressurized and it causes a flood condition. Overnight, the fuel drains back and the pressure drops so he can start. It would mean that it's not temperature related.

 

[ThunderbirdSport]

The ECT is actually called a CHT, but you're correct, it's under the intake, passenger side head, and is easy to get to.

If the intake is out of the way.

 

[michael loibl]

I wasn’t sure if CHT sensor applied to 3rd gen 4.6 liters, when they were 2 valve per cylinder. I’m mainly familiar with the 4.0Noooo

Anyhow, now I’m curious

 

[Explorer_PL]

Update:

I was able to stop by with my Forscan and he just came back from work so the car was very hot.
2 codes were present:
P0128 - Thermostat stuck open
P1289 - CHT sensor high
The temperate reading was going from 148 to negative 42 F and the gauge on the dash was not moving.
It seems that the PCM was thinking the engine is cold so it was overcompensating with fuel and flooding the cylinders. It eventually started after a long cranking but it stunk of fuel.
I am not sure if the thermostat error is just side effect of the sensor or it's really stuck.
TBird Sport - yes, the CHT is right there under the intake manifold , very simple.
I removed mine twice lately and it was not that bad on 06. His 03 looks much busier with linkage to the throttle body and bunch of other stuff.

 

[ThunderbirdSport]

I will say this, mine got better mileage (duh!) once I replaced the CHT and as an aside (the main course, if you will) the AC started working as it should

 

[Explorer_PL]

The final update. Replaced the CHT sensor and the temp gauge works and the car starts every time now, hot or cold.
The manual called for removing the intake manifold which on the 3rd gen is a royal PITA. The 3 valve intakes are baby stuff compared to the old linkage type throttle bodies on the older 4.6's.

To save myself the headache, I cut a 19 mm 3/8 socket an inch shorter, I also found an old 19 mm combination wrench and cut it in half to create 2 stubbies. With those "special" tools I was able to replace it saving probably 4-5 hrs.
There is still some small leak since most of the 4.6 2 valves have the intake leak issues from the research I did.