Bogging down under load?

[foremanxlt]

Hello everyone. I've tried many approaches to fixing my problem, but its not getting any better so i figured i would call on you knowledgeable explorer lovers to point me in the right direction.
I have a 92 XLT with 170k and have had it about 8 months. It sat a couple years so besides brakes, i replaced the fuel pump and sending unit, fuel filter(twice now). It ran great until a few days ago, and now it has a rough idle and if i use more than half pedal, it boggs down and acts as if its running out of gas, but it pushes black smoke out of the exhaust. I thought it could be a clogged fuel filter, so i put another in....nothing. Then i noticed the cats were glowing orange. Figuring they were plugged and making it run rich, i gutted them.....No help. I checked the coil packs, they are fine. All the wires and plugs check out ok too. The only change i've seen is removing this little solenoid from the vacuum hose inline with the Vacuum canister. Could that solenoid and the casister be plugged? It isn't perfect, but i can give it much more pedal before bogging now, and the check engine light is off. Also, it isn't running mega rich under normal conditions either.....I could really use some insight...Thanks

 

[aldive]

Have you checked the fuel pressure?

 

[foremanxlt]

No, not with a gauge i dont have one. But when i released the pressure from the valve on the fuel rail, it shot out pretty good. I used to be a 5.0 mustang owner(4 of them) and it semed to have good pressure, however i'm not able to measure it under load or anything like that.

 

[BeauJ]

Run a can of Seafoam through it and a few bottles of fuel injector cleaner? Are you getting gas from the same gas station every time?

 

[Lt.Jim]

I'm with Beau... Seafoam!

 

[foremanxlt]

No, i mix up stations, no biggie there. And i have really good luck with Redline cleaner, ran a can of that in it, no change. Also, when changing the fuel filter, i turned the engine over via the key with the filter out of the loop, and gas was gushing through the lines the way it should be.....Plus, it seems to be loading up with gas, not the opposite hence the black smoke of running rich, its got me very confused..........

 

[Longjohn119]

What about the fuel pressure regulator? If it's not doing it's job you would have way too much pressure at the fuel rail and hence the rich mixture

I doubt a cleaner will fix you problem but I would run some through it AFTER you fix the problem, running rich will really carbon up a motor

 

[boominXplorer]

sounds like a mass air problem. Try to get the codes read

 

[foremanxlt]

I had the codes read, it came up with the TPS, one o2 rich, one lean......I swapped out the TPS, and no change...........

 

[aldive]

I had the codes read, it came up with the TPS, one o2 rich, one lean......I swapped out the TPS, and no change...........

Post what the codes were.

 

[boominXplorer]

I had the codes read, it came up with the TPS, one o2 rich, one lean......I swapped out the TPS, and no change...........

Those are symtoms related with a faulty mass air sensor

 

[foremanxlt]

Boomin, rock on! I unplugged the mass air and ran it without it plugged in, and although its a bit rich still, all symptoms are gone! Looks like i'll be investing an a new MAF tomorrow. Thank you for all the help guys.

 

[DeRocha]

The MAF may just need to be cleaned...
Take a peak at the thread on How to clean the MAF.

 

[custom20aj]

What about the fuel pressure regulator? If it's not doing it's job you would have way too much pressure at the fuel rail and hence the rich mixture

I just had an interesting one this weekend (1992 Ex). The engine was getting WAY too much fuel. Black smoke and gas out of the exhaust. Sounded like it was running on 3 cylinders. It ended up that the diaphragm on the fuel pressure regulator had a hole in it. If I unplugged the vacuum line from it, gas would shoot out where the vacuum line attaches. This meant the gas was being "sucked" through the vaccum line right back into the engine, flooding it out.

I've read on these forums where a lot of people have had this happen to their vacuum shift modulator on the A4LD tranny.

I'm glad I found it, but I don't understand why the vacuum shift modulator I replaced 2 months ago while repairing the tranny cost $15.00, but the fuel pressure regulator cost $72.00. Seems like a rip since they're about the same size.

 

[foremanxlt]

Well, i have a deeper issue apparently. After changing the MAF, it ran ok for a day or two, then started back up but got worse....So, i checked out the fuel press. reg and it was bad...Replaced it and the gas soaked plugs....Ran ok for 10 min., then seemed to run lean or something, because now there's no excess fuel coming from the regulator, but it stalls and has a very unsteady idle, sort of like a muscle car with a big cam in it.....Now i'm stumped.....Oh, i replaced the fuel pump again too....Any other advice? I'm about to "Thelma and Louise" this truck(with out me in it of course)

 

[laurab]

hi did you regap your plugs to specification if they too much gap it will run like crap somtimes it is the little things that you do i had same problem as you and changed evrything i could think even the plugs but i gapped the same as the old ones so it didnt run any better so wen i rechecked them again with gauge they were off and now its been running great for 2 weeks let me know if that helped you

 

[MrShorty]

After all you've done, what is the fuel pressure at the fuel rail? What do you mean by, "because now there's no excess fuel coming from the regulator?" Is it possible that you've got the fuel pressure plumbed in backwards (fuel rail should be upstream of the FPR and the return line attached to the FPR)?

What were the codes? Was the TPS code a KOEO KOER or CM code? Were the O2 sensor codes KOER or CM codes? I find it interesting that you had both a rich and lean O2 sensor code. I think it would be interesting to investigate the apparent contradiction. Have you cleared the CM codes? If so, are you still getting the same codes, or are they different now? If you can't already, I would suggest you learn how to pull codes yourself (see www.troublecodes.net/Ford or any other of the many sites with EEC-IV test instructions).

 

[custom20aj]

Did you remember to hook back up the vacuum line to the regulator? Any vacuum leaks?