91 X runnin like crap

[liqhx2]

Hello all where to start maybe 180,000 miles hmm to many maybe
1st truck running EXTREAMLY rich i mean full on rich getting about 8-9 mpg :fire:
cel = o2 sensor running lean?? but truck running full rich hmm bad o2? replaced o2
truck still idles rough and surges from 500-900 and die's pretty easy and no power.....
truck still blowing black smoke when gas pushed i ran it running it rich for a long while so i think its carbon build up not running rich....
i've cleaned maf not to long ago and IAC
i guess my ?? is where should i start looking for the ideling problem...
what order should i go in locating where the problem is.
what will alot of carbon build up muck up? what should i use to clean up the problem also i get alot of valve train chatter and kind of job is it to replace rockers and pushrods i've never worked on a 4.0 always worked on honda's,toyota's and ford 3.8 head gaskets(done about 8 now windstars are a major pain in the rear) thanks alot for these forums they kick @**

 

[liqhx2]

ok will i've tried a propane test for vacum leakage that's not it .... could the fuel regulator be pushing to much gas into the injectors? how would i test for bad regulator? Thanks Chris
EDIT i also pulled code 66
another edit: i just disconnected the mas a couple times to see if it changes the idle at all and it doesn't so is it a bad mas?

 

[MrShorty]

Need to be careful. Codes point to circuits, not components. A code 66 could be a bad MAF, it could just as easily (if not more likely) be caused by a bad connection between the computer and the MAF.
1st question I have for you: Is the 66 a KOEO hard fault, continuous memory code, or KOER code? General procedure is to resolve KOEO hard faults first, then move to KOER codes, and only after getting pass codes for those two tests do you work on continuous memory codes.

As for the regulator, yes it is possible for the fuel pressure regulator to cause the engine to run rich. 1st, and probably most common failure mode for the regulator, is for the internal diaphragm to rupture, which allows excessive amounts of fuel into the intake through the vacuum line attached to the FPR. Pull the vacuum hose off of the FPR and see if there is gasoline in the line. Gas in line=bad FPR.
Beyond that, the best way to begin diagnosing fuel delivery issues is to hook up a pressure gauge to the Schrader valve on the fuel rail, and run through a series of tests to see what the fuel pressure is (Should be ~35-45 psig).

 

[DMan446]

You might want to check/replace the TPS(throttle position sensor). IF it is bad, then it is inacurately telling the CPU where your throttle is positioned at. So if it is telling the CPU it is at/near WOT, the cpu is dumping more fuel to run the engine at those conditions, BUT the throttle body is not alowing enough air in cuz obviously its not at WOT.

Just a thought, but something to check out.

 

[liqhx2]

i'm almost 100% positive that the tps is good and working properly does anyone have a pic of where the regulator is and where the vacum is on it ? thanks for the replys Chris

 

[liqhx2]

found the problem FPR its pushing fuel into the vac is there any way to bypass it for right now? and what tools do i need to change it out? Thanks Chris

 

[MrShorty]

Can't really think of any way to bypass it. If you disconnect the vacuum line, then that fuel that was being sucked into the intake would be sprayed into the engine bay. Might get away with it, but then again, you might start the engine on fire. Best thing is to get it replaced.

 

[gt_stang88]

I think all you need to change the FPR is a 8mm socket and ratchet, it's easy to do. Let me know if the FPR fixes your problem.