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2001 Ford Explorer XLT 4.0l Misfires

mozdzierz

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November 21, 2015
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City, State
Oxford, PA
Year, Model & Trim Level
01 Ford Explorer XLT 4.0l
I've had my Explorer since it was new. I've to remove the heads, because an extractor broke off in the head, while trying to remove a rusted in exhaust manifold stud. After replacing the heads, the engine is experiencing misfires. The compression is good in all cylinders and spark is present. Based on my latest troubleshooting step, fuel pressure, I got a reading I don't know how to handle. So, I would like anyone's help. When I hooked up the fuel pressure gauge, it reads a steady pressure of about 65psi. My Haynes book states, that the pressure should be 30 to 45psi at idle, with vacuum hose attached to the fuel pressure regulator. It states that the pressure should be 40 to 50psi, with the regulator detached. It also states, that the fuel pressure should increase considerably, when the vacuum hose is removed. Well, like I stated before, the pressure is 65psi all the time, and when I remove the vacuum hose, the needle only jumps slightly and returns to 65psi. The engine misfires at around 4000 rpm, as when it does, the fuel pressure gauge needle jumps, as the engine misses. Since my knowledge of fuel injected systems is not as vast as I would hope, I'm asking any fellow 4.0l SOHC engine owner with more knowledge of the fuel system for help?
 


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anti eloi

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March 12, 2015
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City, State
Austin, TX
Year, Model & Trim Level
'98 Explorer XLT 4.0 SOHC
The 30-45 is for the fuel injection systems that have return lines.
I am pretty sure that 2001 has only one line and the fuel pressure regulator is in the fuel tank.
You should have 65 psi at all times.
The small can with the vacum line running to it that is on the fuel rail is not a pressure regulator. It is a damper and the line is atttached to it to capture the fuel in the event the diaphragm in the damper ruptures.
To confirm that you have the single line 65 psi system just visually verify that there is only one line coming off the fuel rail.
 




mozdzierz

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November 21, 2015
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City, State
Oxford, PA
Year, Model & Trim Level
01 Ford Explorer XLT 4.0l
Yes, it doesn't have a return line.

Thank you for your help on the fuel pressure. If I wanted to continue asking for help, as to the cause of the misfire, should I start another thread? Since I can't seem to narrow it down, I'll have to start from the timing of the cams as my next question. I wanted to confirm my belief in the cam timing in these SOHC's. I have the timing kit for it and set it as described. So, my belief is, that the miss isn't from the cam timing, since that is the static ignition timing. In so being, the chances of the engine seeming to run smoothly until 3500 rpm, would not happen, if the cam timing was off. I've been working on vehicles for a long time, but my Explorer has me stumped!
 




anti eloi

Active Member
Joined
March 12, 2015
Messages
54
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7
City, State
Austin, TX
Year, Model & Trim Level
'98 Explorer XLT 4.0 SOHC
As long as you followed the proceedures using the cam timing kit then I would agree with you that the miss isn't cam timing related.
Does the miss cause the check engine light to illuminate? If so what are the codes?
Without seeing the engine run I can only say to check eveerthing that you took apart when removing the head.
Have you verified that the miss is on the bank from which you removed the head?
If possible see if you can isolate the miss firing cylinder or if not than it is a random miss.
Keep after it man.
 








mozdzierz

New Member
Joined
November 21, 2015
Messages
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City, State
Oxford, PA
Year, Model & Trim Level
01 Ford Explorer XLT 4.0l
Have done that.

I've replaced all the plugs and wires. It's like I said, I've been working on vehicles for a while.
 




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