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Discussion Starter #1
Ok...so I have been going over several forum posts searching for others that have had a similar issue and no luck. I was hoping to hear some advice or options from others. Its a 1995 bronco...5.8L, 130,000 miles Eddie Bauer. I haven't found anything that relates to this issue. After the bronco runs for a while, anywhere from 30 minutes and longer(although it has had this issue quicker), so maybe its a heat issue? it will randomly lose power. I can kind of describe it as a "limp mode". The bronco will run, but no matter how much throttle you give it, it won't get over 2000ish RPM's and then sputters/pops. It will maintain that power range but wont gain additional power. If I had to make it up a steep hill, it might not have the power to make it up. When in this mode, it idles fine and seems to run fine, just no power.

But here is the kicker...if I shut the motor off, turn it back on, it runs fine. I can step on the throttle and it has full power. This full power will last for a random period of time, anywhere from a few hundred feet to 15 miles or more, before going back into that "limp mode". Occasionally, as its in this mode, the check engine light will come on. The check engine light doesn't always come on though, just randomly...and sometimes it goes off by itself.

I had someone look at it and he put on a fuel pressure gauge as it went into this "limp mode" and found that the fuel pressure was low. We ended up putting a new fuel pump in. This seemed to fix the problem..for a few months, then it started again.

I put on a new fuel filter, new fuel pressure regulator. As a side note, the bronco had a bad radiator so it ran hot for a while...this made me also think it could be a heat related problem. I put a new radiator, thermostat, hoses etc and it runs cool..but still has this random losing power/fuel pressure problem. the part that is really getting me is the fact that I can turn off the Bronco and it seems to "reset" and run fine for a while, before failing again....

I was wondering if anyone has heard of this or any advice on what route I should take to get this fixed.
Is there a sensor I should look into...
Thanks for the help
 

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yo WMJ1996,
Does the Check Engine Light (CEL) come on briefly when the ignition switch lock cylinder is turned to ON? It should turn off when the engine starts. If the check engine warning indicator does not come on when the ignition switch lock cylinder is turned to ON or if it comes on while the vehicle is moving, the system is malfunctioning
If the CEL does not light up at all when starting it; then suspect that bulb is burnt-out or loose, socket was damaged by PO or shop, etc. or someone removed it.

Have it scanned for Codes @ local parts store.

Ensure engine is still @ normal op temp.


also, is the Transmission Control Indicator Light (TCIL) at end of shifter stalk blinking randomly while this situation occurs?

The Transmission Control Switch (TCS) aka OD is a momentary contact switch. When the switch is pressed, a signal is sent to the powertrain control module (PCM) (12A650). The powertrain control module then energizes the Transmission Control Indicator Light (TCIL) and the coast clutch solenoid, applying the coast clutch to provide engine braking and cancels fourth gear operation. The TCIL indicates overdrive cancel mode activated (lamp on), electronic pressure control circuit shorted or monitored sensor failure (lamp flashing).
Press this switch and the word OFF will illuminate on the shift lever knob. With the word OFF illuminated, the transmission will operate in gears one through three. Operating in overdrive OFF gives more engine braking than overdrive and is useful for descending hills.

To return the transmission to the normal overdrive operation, press the transmission control switch again. The switch may be used to select overdrive or overdrive OFF at any time the vehicle is being driven.

If the transmission control indicator light is flashing on and off repeatedly, the transmission system is malfunctioning. The transmission will operate in a failure management mode with harsh engagements, firm shift feel, and abnormal shift schedule.

Maybe a Code will show it is in Failure Mode Effects Management (FMEM); FMEM is an alternate system strategy in the PCM designed to maintain vehicle operation should one or more sensor inputs fail. When a sensor input is perceived to be out-of-limits by the PCM, an alternative strategy will be initiated. The PCM will substitute a fixed in-limit sensor value and will continue to monitor the faulty sensor input. If the faulty sensor operates within limits, the PCM will return to the normal engine running strategy.
 

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Discussion Starter #3
Hi thanks for the replies. The check engine comes on then turns off once the motor is running. The O.D. On/off light has not lit up when this situation occurs.

As far as the fuel pump, it was the FDM that was replaced. Could it be an issue with the fuel sending unit?
 

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Hi thanks for the replies. The check engine comes on then turns off once the motor is running. The O.D. On/off light has not lit up when this situation occurs.

As far as the fuel pump, it was the FDM that was replaced. Could it be an issue with the fuel sending unit?
It could be the fuel sending unit, maybe its bad. But if its running fine for a while then it starts losing power it sounds like something might be getting clogged up to me.
 

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Discussion Starter #5
A friend put the FDM in...Im not sure what brand. Yes..the part that is baffling me is when I turn the Bronco off, then restart it, it runs fine again...for a short time, then goes in that "limp" mode. Can it be something electrical? maybe a sensor is sending a signal causing it to go in that limp mode, then when i turn it off it stop that signal??

Also..could it be a tranny issue? When in that limp mode it wont shift...not matter how hard I stomp the throttle it just stays at around 2000rpm..
 
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