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-   4.0 SOHC / 4.0 OHV Tech (http://www.fordrangerforum.com/4-0-sohc-4-0-ohv-tech/)
-   -   Running extremely rough after being driven. (http://www.fordrangerforum.com/4-0-sohc-4-0-ohv-tech/139352-running-extremely-rough-driven.html)

Laidout98 11-07-2016 12:33 PM

Running extremely rough after being driven.
 
Howdy folks,

My 1994 4.0L runs great from cold crank to my destination (roughly 30-40 minutes of driving). Vitals look good, nothing past normal. If I turn the truck off for about 5-10 minutes and go to crank it up again, it runs EXTREMELY rough as if someone pulled a spark plug off. If I feather the throttle and hold it around 2500 rpm (I know I will be scolded for that) for a matter of about 5-10 seconds, it smooths out as if no problem existed. Plugs and wires were done about 10K miles ago with OEM parts.

HELP PLEASE! :confused2: :hmmmm2:

Thank you in advance for any helpful advice!

henryford 11-07-2016 06:06 PM

Re: Running extremely rough after being driven.
 
maybe a MAF sensor in the intake system?? just a guess 9 not regulating the fuel mixture properly ???

DangerRanger37 11-07-2016 06:58 PM

Re: Running extremely rough after being driven.
 
When was the last time you changed your fuel filter? Sounds like fuel's not getting there with out a little help. Possible fuel leak as well or failing fuel pump. I'd start with the fuel filter though.

Laidout98 11-07-2016 08:57 PM

Re: Running extremely rough after being driven.
 
Thanks guys. The sending unit (fuel pump) has been replaced with the motorcraft about a year ago. The fuel filter as well but I'll check both along with the maf as well!

Jswifto 11-08-2016 04:03 AM

Just because you did plugs and wires a few months ago does not mean you might not have a cracked plug or a wire not seated all the way.

cowboybilly9mile 11-08-2016 10:28 AM

Re: Running extremely rough after being driven.
 
Knowing the history on causes of the problem, first thing I would do would be to check the FPR to make sure the diaphragm hasn't ruptured. To do this takes less 60 seconds.

Laidout98 11-10-2016 12:45 PM

Re: Running extremely rough after being driven.
 
I have checked plugs and wires. Everything seems fine.
I'll check the fuel pressure and go from there.

cowboybilly9mile 11-10-2016 01:46 PM

Re: Running extremely rough after being driven.
 
Quote:

Originally Posted by Laidout98 (Post 2686639)
I have checked plugs and wires. Everything seems fine.
I'll check the fuel pressure and go from there.

The regulator, your symptom is consistent with a failing FPR. A failing FPR DIAPHRAGM can/will produce the problem you've got, yet it runs great as you described and it will pass a pressure test. A leak causes fuel to bleed into the vac line and then the intake, and they act flooded when trying to start a warm engine. The only thing needed to test for this is your nose.

Laidout98 11-10-2016 01:54 PM

Re: Running extremely rough after being driven.
 
I have noticed a faint smell inside the cab as well as outside the truck that smells similar to fuel.
Where is the FPR located? (sad that I just asked that question, I know)

cowboybilly9mile 11-10-2016 02:16 PM

Re: Running extremely rough after being driven.
 
On my 94 it was on top and back of the engine, and follow fuel lines to the device with a vacuum line attached. I believe it was more on the left (drivers) side and not dead center.

Laidout98 12-04-2016 03:00 PM

Re: Running extremely rough after being driven.
 
Update -
I replaced the FPR with the motorcraft replacement part. When in with ease. Drove the truck for a couple of days and no change. I have not smelled fuel as of yet though.
Any other ideas out there? The symptoms are the same since the part has been replaced.

Rangerman88 12-04-2016 03:49 PM

I sometimes have this issue and it is a spark plug for me usually. I just pull it and throw a new one in when it happens.

DangerRanger37 12-04-2016 09:26 PM

Re: Running extremely rough after being driven.
 
Pull the fuel filter man, its probably time anyways.


Otherwise I'd say check the fuel pressure. The fact that you have to feather the gas to prevent stalling says fuel delivery problem or combustion issue. Any CEL?
If no misfire shouldn't be a combustion issue, maybe a bad plug/ wire

Laidout98 12-20-2016 10:27 AM

Re: Running extremely rough after being driven.
 
Fuel filter has been replaced with the OEM filter. No change, no CEL either. I'm going to check the plugs to see how they look. I replaced them about 5-10K ago. This issue has been pre plug and wire replacement.

DangerRanger37 12-21-2016 10:47 AM

Quote:

Originally Posted by Laidout98 (Post 2694127)
Fuel filter has been replaced with the OEM filter. No change, no CEL either. I'm going to check the plugs to see how they look. I replaced them about 5-10K ago. This issue has been pre plug and wire replacement.

Unplug your IAC while running and see if theres a change in the motor


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