Fuel Issue I can't figure out, No CEL

[Kiliona]

1992 Ford Explorer, XLT manual tranny, 4 L 3.73 gears stock etc etc

New to posting, but I've Lurked here for a while, I've searched everywhere and I just can't figure this out.

What's Wrong​

This problem only occurs when it is hot outside, and generally if not always after the engine is still warm (recently ran) and I drive it. The car is running what seems to be very rich (GF drove behind me and told me it smelled like gas and there was charcoal smoke out the exhause) so rich that it'll bog down and die sometimes. Sometimes right after i start it, sometimes after i've been driving it and let it drop down to an idle. When it's running really bad (too bad to move the car) and i try and get the rev's up it'll make a noise akin to a fan rubbing a shroud or something. Once again no check engine light! which is one of the weirdest things to me because that rules out most sensors and such.

I've realized lately when i need to get it home i can pull over (generally the car will die and make the "pull over" choice for me), pull the fuel pump fuse, roll the car over (it'll still start once or twice with the fuel fuse out ) roll it over some more, then put the fuse back in start it and don't let the revs drop bellow 2000. Sometimes even when the revs are high it'll still die and i'll have to do this again. My logic is that the cylinders are flooded with fuel and this cleans it up a bit, not sure if that's true.

This car is new to me as of a month ago, and this problem didn't occur until two weeks after i did the valve cover gaskets (had to pull intake manifold, vacuum hose tree, 4 or 5 various sensors, alternator, power steering pump, couple other things) Then i went on to do a tune-up (parts replaced stated below). I don't think the work i've done is related but it's possible i screwed something up and i caused the problem. But the problem started after it got hot outside, and it wasn't hot till after i did all that work. like two weeks later.

Link to video of EOKO test, pulling codes.
http://s1365.photobucket.com/user/jazzmo_94/media/IMG_18741_zps2008240a.mp4.html?filters[user]=136822375&filters[recent]=1&sort=1&o=0

What i've replaced/tried​

First things first, i replaced the valve cover gaskets (had an oil leak) which involved pulling out all the stuff i mentioned above. I also replaced the intake manifold gasket while i was at it. I SHOULD have done the fuel rail gaskets while i was at it but didn't.

Next i did a tune-up, all this was before it warmed up and before the problem occured. I replaced plugs, wires, air filter,

Now that the problem occurred (ironically while i was droving down the canyon with a trailor to save a friend who got a flat on his motorcycle, my car broke down) i tried replacing things i thought might fix the problem. Started with fuel filter, that helped so i could use my fuse trick mentioned earlier to get the car home if i needed to. Then i did the fuel pump relay, didn't make a difference. Today i replaced the Fuel Pressure Regulator, that once again helped, but definitely didn't fix it.

Misc.​

The owner before me was very ****, he ordered the car brand new in 1991 (or 2) and kept mini notebooks and receipts of everything he has ever done to the car. Including gas mileage at every fillup.

Using this i found-out the fuel pump was replaced in 2011, 2 years ago, plus i can hear the fuel pump turn for a few seconds when i turn the key to on, PLUS I still believe it's running rich and don't believe a fuel pump would do that.

The problem initially felt like a vapor lock, i know that's very unlikely in a fuel injected engine, but it felt like it.

Sorry for this being so long. Thanks for the time anyone spends on helping me! Any help is appreciated, and i can give more info if needed.

Reader's Digest​

Help, 92 explorer XLT running (probably) super rich when hot,
Running very rough when hot especially on hot start, Replaced fuel filter FPR and fuel relay, did tune-up, not fixed.

Any advice on which sensors to look at and how to test them, or anything else would be very useful!

 

[Kiliona]

Oh i forgot to add, when it's hot and i turn it off, i can hear a loud hissing sound (like pressure being released) coming from the driviers side of the engine. It sounds more like it's coming from the area near the brake booster or steering column then from the actual engine. I know that this generally happens when vacuum lines release pressure and is sometimes normal, but this is audible from the passenger compartment with doors closed and windows up, and lasts 4-7 seconds.

 

[arco777]

If you're running rich you can probably rule out vacuum leaks and such, but I'd lean towards a faulty sensor such as a bad MAF giving wonky readings. Try swapping some of your old sensors back on and see what happens. After replacing a sensor, clear the memory (disconnect batt for 5+ minutes).

Also check your TPS voltage. At closed throttle it should read about .95-.98v. If you are new to this, of the three wires one is a ground, one is a reference (5v I think) and one is a rising voltage based on position; compare the ground to this wire. As you open the throttle (key on, engine off is fine) you should see the voltage rise smoothly, to a WOT reading of 4-5v.

You may not see a CEL, but try running a KOER test and a cylinder balance test. They might give you a hint.

 

[Kiliona]

Yeah, i am definitely glad it's running rich not lean, lean is more deadly. I tried cleaning my MAF but that didn't fix it, anyone know which sensors are compatible from a mustang to an explorer? i don't have another explorer to swap parts around and see. Honostly i doubt the sensors are compatible since i have 2 SN95 mustangs (one is a parts car). I have dont TPS before, i'll try that thanks for the idea. I will also try pulling codes to see if there is a code that isn't throwing a CEL

Also for anyone who reads this a cool trick to reset computers (in cars) faster is to take off the negative cable then quickly tap it on the positive cable, this will remove any residual voltage from the system. I've never heard of this being bad for the car, so if anyone thinks it is for some reason just let me know.

Does anyone know how to tell if a fuel rail gasket or a fuel injector is just simply leaking extra fuel into the cylinder, that is without pulling half the engine apart? I may be able to get the injectors off to check for cracks/whatever without pulling too much apart.

I'll try the TPS, and look at the injectors, and find a way to test the MAF when i get home, outta town for eight days. Oh, and thanks arco!

 

[Kiliona]

Also, i'm going to try and get one of those ford OBD1 code puller thingies, that might help a ton.

 

[arco777]

Re:

Yeah, i am definitely glad it's running rich not lean, lean is more deadly. I tried cleaning my MAF but that didn't fix it, anyone know which sensors are compatible from a mustang to an explorer? i don't have another explorer to swap parts around and see. Honostly i doubt the sensors are compatible since i have 2 SN95 mustangs (one is a parts car). I have dont TPS before, i'll try that thanks for the idea. I will also try pulling codes to see if there is a code that isn't throwing a CEL
If it's a 5.0 Mustang, I know the Fox body Mustangs should interchange on the TPS, and the MAF in some cases can interchange. Even if the MAF is not the exact same calibration, often it will work well enough to tell if your factory MAF is good. I used an Explorer MAF on my Taurus SHO one time and it worked well enough for test drive purposes. Many other Ford sensors are pretty close in calibrations for testing purposes.

Does anyone know how to tell if a fuel rail gasket or a fuel injector is just simply leaking extra fuel into the cylinder, that is without pulling half the engine apart? I may be able to get the injectors off to check for cracks/whatever without pulling too much apart.Use a fuel pressure gauge attached to the fuel rail test port. Prime the fuel system. You should see pressure pop up to 35-40PSI and stay there. If it leaks down quickly you have a leaky injector or regulator. If it does not build up enough pressure, suspect the fuel pump. If it builds over 40PSI, the regulator is likely bad. Another thing you can do is use a mechanic's stethoscope to listen to the injectors themselves while the engine is running. They will "click click click". If one was sticking perhaps you could hear it sounding differently.


Another thing to look at is if one cylinder alone is acting up. Check for one spark plug that looks different from the others. Another test is while the engine is running, compare temperature of the exhaust manifolds at each cylinder. This is usually used to find a misfiring cylinder by finding the "coldest" exhaust point, but in your case might help isolate a problem cylinder.

Right now I would suggest doing some reading if you have time. Check out http://oldfuelinjection.com/ and read some of the articles on how the Ford fuel injection works, along with troubleshooting guidance. There is a ton of good info there. It is made more for late 80s to early 90s Mustangs and Broncos and such, but the same principles and tech are used in the Explorer and most of the info is the same.

 

[Kiliona]

Yeah, i am definitely glad it's running rich not lean, lean is more deadly. I tried cleaning my MAF but that didn't fix it, anyone know which sensors are compatible from a mustang to an explorer? i don't have another explorer to swap parts around and see. Honostly i doubt the sensors are compatible since i have 2 SN95 mustangs (one is a parts car). I have dont TPS before, i'll try that thanks for the idea. I will also try pulling codes to see if there is a code that isn't throwing a CEL
If it's a 5.0 Mustang, I know the Fox body Mustangs should interchange on the TPS, and the MAF in some cases can interchange. Even if the MAF is not the exact same calibration, often it will work well enough to tell if your factory MAF is good. I used an Explorer MAF on my Taurus SHO one time and it worked well enough for test drive purposes. Many other Ford sensors are pretty close in calibrations for testing purposes.

Does anyone know how to tell if a fuel rail gasket or a fuel injector is just simply leaking extra fuel into the cylinder, that is without pulling half the engine apart? I may be able to get the injectors off to check for cracks/whatever without pulling too much apart.Use a fuel pressure gauge attached to the fuel rail test port. Prime the fuel system. You should see pressure pop up to 35-40PSI and stay there. If it leaks down quickly you have a leaky injector or regulator. If it does not build up enough pressure, suspect the fuel pump. If it builds over 40PSI, the regulator is likely bad. Another thing you can do is use a mechanic's stethoscope to listen to the injectors themselves while the engine is running. They will "click click click". If one was sticking perhaps you could hear it sounding differently.


Another thing to look at is if one cylinder alone is acting up. Check for one spark plug that looks different from the others. Another test is while the engine is running, compare temperature of the exhaust manifolds at each cylinder. This is usually used to find a misfiring cylinder by finding the "coldest" exhaust point, but in your case might help isolate a problem cylinder.

Right now I would suggest doing some reading if you have time. Check out http://oldfuelinjection.com/ and read some of the articles on how the Ford fuel injection works, along with troubleshooting guidance. There is a ton of good info there. It is made more for late 80s to early 90s Mustangs and Broncos and such, but the same principles and tech are used in the Explorer and most of the info is the same.

I don't know how i didn't think of the fuel pressure tester, i guess because i don't have one haha but i can go buy one. Honestly that probably should have been the first thing i did, huh?

Exhaust temperature and stethoscope are good ideas as well.

Wouldn't a miss-fire throw a CEL? (atleast if it is bad enough, which it should be with the performance issues i've been having.)

Also if it were simply 1 cylinder, or two, or even three, i feel like the truck would still be driveable, but it's nowhere close. That's why i suspected that if it were an injector problem it'd be a problem that affected every injector not just one.

I'll take another look at it when i get back into town. I think i'll be able to figure it out now with all this new info, then i'll post the solution here.

 

[arco777]

In my experience, misfires rarely throw a code. Running a cylinder balance test does work a bit better to pinpoint a weak or misfiring cylinder, but for it to produce reliable results the engine has to be running halfway decent. You could try it anyways just for s&g.

 

[Kiliona]

Alright i tried pulling the codes, it was actually more confusing than i expected.

They came out to be

33 EGR not opening
123 TPS high
122 TPS low
54 IAT high reading
Then a few more that i wasnt sure of but had to do with EGR or EVP.

This is great, i thought, if the EGR was sticking open or shut that'd explain why itd run like **** and not start and smell like gas (egr stuck open) but sometimes it'd be fine just less fuel economy and maybe less power (egr stuck closed), but then i took a look at my throttle body and realized there isn't an EGR on my truck (it's a 92).

Now i'm totally lost, EGR issue would explain the problem, to me, and i'm even getting EGR codes, but i don't have an EGR..?

Anyone know what's going on? i'll keep trying to figure it out but it's getting very frustrating.

Perhaps it means PCV not EGR or something weird like that..?

I used http://www.explorerforum.com/forums/showthread.php?t=160035 to see what the codes meant.

 

[MrShorty]

My '92 output 3 digit codes, not 2 digit codes. I know that the '91 4.0 L engine output 2 digit codes. I would expect it to either output 2 digit codes or 3 digit codes, not both.

Is it possible the initial 33 you list was really 111 KOEO pass? The last code may be a 542 or 543 fuel pump circuit code (probably set when you try to start the engine with the relay pulled out)?

TPS is fairly important (not as important as MAF or O2 sensor, but still important) in A/F mixture calculations. If there is something wrong with the TPS signal, that could be what is causing the rich condition. I would look further into the TPS codes.

 

[Kiliona]

Hmm it's a little dusty, but heres the actual sequence jsut against someone wants to tell me how i'm retarded and reading it wrong x D

http://s1365.photobucket.com/user/jazzmo_94/media/IMG_18741_zps2008240a.mp4.html?filters[user]=136822375&filters[recent]=1&sort=1&o=0

 

[Kiliona]

My '92 output 3 digit codes, not 2 digit codes. I know that the '91 4.0 L engine output 2 digit codes. I would expect it to either output 2 digit codes or 3 digit codes, not both.

Is it possible the initial 33 you list was really 111 KOEO pass? The last code may be a 542 or 543 fuel pump circuit code (probably set when you try to start the engine with the relay pulled out)?

TPS is fairly important (not as important as MAF or O2 sensor, but still important) in A/F mixture calculations. If there is something wrong with the TPS signal, that could be what is causing the rich condition. I would look further into the TPS codes.

I was just looking at what seemed to be longer than normal pauses and took that as a new code starting. I really need to just get an OBD1 code reader that'll put it in black and white for me, both my girlfriend and I were confused as to where the codes started and began and what meant what. Which is sad since it seems like a relatively simple process.

I've done the TPS voltage tests before on a different car (probing the circuit, looking for voltage rises, etc) i'll look at that next time i get a chance.

Another thing i tried a few weeks ago (it's been sitting for ten days) was pulling a few sensors and seeing if it ran better without them. One of those was the TPS, i assumed it'd go into open loop and run better (but not best) if the TPS or another sensor was the problem but that didn't help. I also unplugged the MAF, and two other sensors i don't remember. (all at seperate times)

 

[arco777]

Reading codes without a reader can be tricky for anyone. An EEC-IV Ford code reader is real cheap, usually $25-40. I use this one (link).

It's true that in some cases disconnecting the MAF will allow you to tell if the MAF was giving a bad reading. But disconnecting the TPS doesn't work that way. The TPS is pretty critical to the ford EEC. Testing it with a multimeter should be sufficient; you should see a ground wire, a 5v reference wire, and a third that sweeps smoothly from .95-.98 at idle up to 4+ volts at WOT.

 

[MrShorty]

My interpretation of your video:

7 sec -- fast codes output -- disregard.
11 sec -- KOEO codes begin (111) then (at 18 sec) repeated (I find that looking for the repeated codes is a good way to help know when you get it right. When I see something in the repeats that I didn't see the first time around, I know I miscounted something).
30 sec -- separator pulse between KOEO and CM codes
35 sec -- CM codes begin (113, 122, 543) and then repeat (at 1:08).