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99 Exp 4.0 sohc random no start when warm

rwing21

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April 25, 2012
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City, State
Louisville
Year, Model & Trim Level
1999 Explorer 4X4 EB
99 Explorer
4.0 SOHC
135,500 miles

So after the explorer would not start twice this week after running into the store, I decided to look into it.

I peformed a fuel pressure test at the rail and had approx 62lbs on prime. Pressure looked great while idling and reving the motor. When shutting off the motor, pressure fell to 0 within 2 minutes.

After reading some threads on here, I wanted to check for a leaky injector prior to dropping the tank and replacing the pump.

So I have the passenger side fuel rail lifted out of the lower intake, and I have primed the pump. Would a leaky injector leak with just rail pressure or does a leaky injector mean it is dumping too much fuel when the engine is cranking?
None of the 3 injectors leaked. I have pulled the plugs on the driver side and none of them looked fouled or wet.

Thanks in advance
 




rwing21

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April 25, 2012
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City, State
Louisville
Year, Model & Trim Level
1999 Explorer 4X4 EB
Got it all put back together with new upper intake gaskets and o rings on the injectors from being pulled. Runs good with no CEL. I have put 160 miles on her so far.

Next weekend I am going to drop the tank and replace the fuel pump assembly and hopefully that will address why I have so much pressure bleeding off.
 




rwing21

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April 25, 2012
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City, State
Louisville
Year, Model & Trim Level
1999 Explorer 4X4 EB
This past weekend I changed the fuel pump. My rail pressure now remains solid at 60psi for at least 15 mins after shut off.

Tested the warm stats and she fires right up without hesitation now. Not sure if it is my imagination or what but the truck feels like it has more power on the top end. Didnt really notice it was lacking.

Once tested, I changed the fuel filter as well.
 




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