Why does my 1993 Explorer lose RPM's while driving?

Tiny
GROUNDROD
  • MEMBER
  • 1993 FORD EXPLORER
  • 145,000 MILES
1993 Ford Explorer 4.0L 2WD While Driving The truck loses RPM's cold or at operating temp. I can give throttle and the RPM's will climb to 2500 or so and drop back down to 1000. If I engage the clutch, turn the ignition off and back on, release the clutch, all is fine. At this time I can rev the throttle and the RPM's will hold at red line. I cleaned the MAF sensor with MAF cleaner and the IAC with brake cleaner. The truck ran fine for 40 to 50 miles then went back to the original problem of losing RPM's. I have replaced the fuel pump & screen (tested at 30 Pounds before replacement but only 29 pounds after ( Auto Zone said it needed to be 35 to 45 Pounds)) Also replaced the fuel filter, Throttle pos. Sensor and MAF sensor. There is apparently no EGR valve on this engine as it should be located near the IAC on the drivers side and it is not. I have read in forums that it might be a weak ignition coil. I am getting tired of the process of elimination game and am hoping you guys will have run into this problem before. Thank you in advance for any information that may help.
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Wednesday, December 21st, 2011 AT 3:08 AM

8 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
When this happens, does the vehicle loose power?
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Wednesday, December 21st, 2011 AT 3:10 AM
Tiny
GROUNDROD
  • MEMBER
Yes, If I am Driving at 60 or 70 the truck wil start slowing down to a crawl. I can engage the clutch and it will not die but will not hold RPM's.
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Wednesday, December 21st, 2011 AT 3:16 AM
Tiny
GROUNDROD
  • MEMBER
Actually, this does not happen at any certain speed. It will lose power at any given speed and any given gear.
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Wednesday, December 21st, 2011 AT 3:26 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
It sounds like a problem with fuel pump pressure. Have any trouble codes come up?
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Wednesday, December 21st, 2011 AT 3:42 AM
Tiny
GROUNDROD
  • MEMBER
The original codes were 2 fuel and 1 vacuum. I don't know what the numbers were but that is what the Auto Zone tech told me. That is when I replaced the Fuel Pump and filter. Then the only hose that I found off was a 3/4 inch line that connected to the Air intake. The tube from the air filter to the air intake. Could there be a problem with the fuel pressure regulator? I also read that in a forum but thought that was to regulate too much fuel from entering into the engine.
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Wednesday, December 21st, 2011 AT 3:52 AM
Tiny
GROUNDROD
  • MEMBER
I found the problem. It was none of the above.
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Thursday, December 22nd, 2011 AT 2:01 AM
Tiny
CJ MEDEVAC
  • EXPERT
BEEN WATCHING THIS ONE

WHAT WAS THE DEAL?

THE MEDIC
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Thursday, December 22nd, 2011 AT 4:32 AM
Tiny
GROUNDROD
  • MEMBER
Sorry to all the readers for the delay, seeing jacobandnickolas didn't seem to want to respond too much I thought it wasn't important. Then I realized that this IS for other people that have the same problems. It was the fuel pump and not. Technically it was the gas tank. It seems the liner in the plastic fuel tank that ford produces starts to deteriorate over a period of time. This "flaking liner" appears to collect on the screen of the fuel pump causing loss of pressure even tho the pump is good. Apparently when the truck is running the pump pressure accumulates this flaking to the pump screen causing loss of pressure. When the ignition is turned off the pump pressure releases the debris from the screen, and when restarted, re-collects it again. I took the tank off and used a 1X2 stick about 14 to 16 inches long and a rag to scrape loose what I could, flushed out the tank and that seems to have corrected the problem for now. The fuel pressure returned to normal and no more stalling. By no means is this a permanent fix. I will track down a new fuel tank and replace it asap.
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Saturday, December 24th, 2011 AT 11:17 PM

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