Hi, on my 92, someone had cut the wires on one of the oxygen sensor's. The other one is still connected but is being replaced today. The odd thing is, that I can't find where he cut the wires, no stubs or any other signs of them. Question is, do I tie into the other sensor wires, or run separate wires, and to where?

 

You should have only 1 oxygen sensor.

 

I guess that explains the no cut wire stubs...interesting that two are installed, the cross over pipe must be from a Stang

 

High tech cork!!!!!

 

Stangs don't have crossover pipes.. they all use duals. Where in the exhaust are the O2 sensors installed?

 

you would have 2 O2 sensors if you have a MASS Air system, which didn't come stock with that truck. Had someone converted from SD to MASS Air, that is when you would need to add another O2 sensor. If the truck has been converted to MASS Air and you have only one O2 sensor, then it would either run like crap or some more wiring could be done at the PCM to get by with using only 1 O2 sensor.

If you have a place for more than one O2 sensor then those don't sound like stock parts.

 

i've been having problems with my '91 f250 5.8L.
most of time it will crank but won't start. i hear fuel pump running and usually won't stop when engine doesn't start. was told maybe fuel press regulator, but not sure where it is, and also was told that if it's connected to vacuum to just pull hose of and if diaphragm is bad fuel will come out.
don't know where it is first of all and second if it's not that what else.
have replaced fuel filter and fuel pump relay...please help.
i am a newbee to this site and was really hoping for some help.
thanks,
foro

 

Welcome...try shooting a little starter fluid in the intake, then crank her, to see if you may have a fuel delivery problem...regulator is on drivers side back of motor, this is what it looks like Fuel Pressure Regulator | 1991 Ford F250 3/4 ton P/U 4WD 8 Cylinders H 5.8L FI Windsor | AutoZone.com...you should start a new thread, and you will get the help that you need ASAP

 

Yea, not MAF...PO installed wrong pipe I quess

 

Definitely start a new thread. Also, maybe you can pull the codes from the computer and see what is stored in there.

 

thanks for the reply.....i thought i was starting a new thread, i am new to this but i'll try.
also, how do i find out what is in the computer.
foro250

 

That's real easy, just hit the new tread button on the left side 1987 - 1996 F150 & Larger F-Series Trucks - Ford Truck Enthusiasts Forums...now retrieving codes is easy too Ford Fuel Injection » How To Run a Self-Test...did you try the starter fluid

 

Ok, quick question. I guess I have some kinda unicorn. I have a 1992 F-250 5.8, definitely SD, definitely batch fired injectors, yet has dual o2 sensors from the factory. According to my Haynes manual they didn't make such a critter, but I have it, factory wiring and all. I'm trying to MAF it with a 94 5.0 harness and an a9l ecm. The Mustang that matches that ecm is a dual 3 wire o2 system and my truck is a dual 4 wire o2 system. According to my Haynes manual it's only showing 95's with dual o2's that are CA emissions. So, how does one go about hooking that up since according to Haynes my truck doesn't exist, the wiring for the o2's is different, and I'm not interested in frying my new ecm?

 

You need to start your own thread. I had a 1992 F350 w/5.8L engine and it was a single O2 sensor setup exactly like the factory manuals state.

The only time I have run across a factory two O2 sensor setup (OBD-I) are 1995 MAF F150 and Broncos. Some photos of your setup are highly appreciated. We do run across extremely rare exceptions to the rule, but a 1992 OBD-I F250HD with factory dual O2 sensors and Speed Density is a unicorn.

Better yet, get a photo of the Calibration code on the driver side B-Pillar. Another request are the actual numbers off the computer currently in the truck.

 

Well, like I previously said, it must be a unicorn. I'll put pics at the bottom, including the original ecm tag even though it went bad years ago and I had to replace it, but the drivers side o2 wiring runs with the tranny wiring, so where the tranny harness plugs in under the hood on the drivers side wheel well. It plugs into the o2 right by where the fuel lines run down to the frame. The wire colors are orange, purple w/ orange stripe, grey w/ blue stripe, and black. The passenger side o2 wiring is in with the starter wiring and the o2 plugs into it right in front of the starter. The wires are orange, purple w/ orange stripe, grey w/ blue stripe, and white w/ pink stripe. Now I know on most of the duel exhaust trucks that they had about an inch diameter crossover pipe right behind the passenger side exhaust manifold and that's where the o2 was installed and that's why the passenger side o2 plug is right in front of the starter. My truck however did not have a crossover pipe (most likely the exhaust had been replaced from the manifolds back), but if it had one from the factory then you would've thought that whoever did the exhaust would've done something to put another crossover pipe in or something similar, but either way it does not explain why there's o2 wiring for the drivers side exhaust. What's also strange is that the o2 wiring for the drivers side exhaust originally ran down the drivers side frame, across the transmission crossmember, then back up the passenger side frame to plug into the drivers side exhaust in front of the cat (both factory exhaust pipes ran down the passenger side) instead of coming out of the passenger side wiring right in front of the starter just like the passenger side o2 unless it was done that way so you wouldn't get the 2 sides mixed up, but either way it was definitely like that from the factory because the factory wiring has not been modified. At first I thought maybe the factory pipes had 2 sets of cats, 2 crossover pipes (one right behind the passenger side exhaust manifold and the other in front of the 2nd set of cats), and that was why it had wiring for 2 o2's, but that doesn't explain why it has the one o2's wiring on the drivers side of the truck running with the tranny wiring. Anyway, if someone knows what the deal is here, and furthermore how to wire the o2's for an A9L ecm, I'd appreciate the info. The first photo is obviously the passenger side, the white plug in front of the starter is the o2 plug, the next one is white o2 plug on the drivers side, I have the o2 wires zip tied to the fuel lines.