88 2.9 runs really rich

[O.P]

It used to run really well, but recently, all of the sudden it started acting up and runs rich. As soon I start it it will run okay for about 4-5 seconds, then it runs like crap. I checked the vacuum lines and they appear to be ok. Replaced all plugs, and both fuel filters. I am getting about 40 psi of fuel pressure. I pulled off IAC motor and cleaned it up. Still continues to run rich. Any ideas? I hooked up a scanner and it could not read the codes.

[maxeff]

O.P
Have you changed the coolent temp sensor?( not the temp sender) If it's bad it will tell the computer it's 40 below zero.

[O.P]

Yes I did, but no change

[way2old]

Look closely at the MAP sensor. If it has quit, the PCM thinks it is running wide open and dumps fuel as if you were driving down the road with the accelerator on the floor.

[Psychopete]

Originally Posted by O.P

It used to run really well, but recently, all of the sudden it started acting up and runs rich. As soon I start it it will run okay for about 4-5 seconds, then it runs like crap. I checked the vacuum lines and they appear to be ok. Replaced all plugs, and both fuel filters. I am getting about 40 psi of fuel pressure. I pulled off IAC motor and cleaned it up. Still continues to run rich. Any ideas? I hooked up a scanner and it could not read the codes.

The easiest way to find the problem will be to scan the codes. Try again or take it up somewhere that will do it for you. Could be a lot of different things, you're going to end up spending a lot of money on parts that could still be good.

Pete

[O.P]

Like I mentioned before, it will not pickup the codes, Also I have replaced the MAP sensor with a known good one. Could bad injectors cause this?>

[Psychopete]

Originally Posted by O.P

Like I mentioned before, it will not pickup the codes, Also I have replaced the MAP sensor with a known good one. Could bad injectors cause this?>

You'll need to find why you can't pull the codes. That right there is a huge problem. It could be a dozen things, but I am not sure if it falls under the problem with the o2 sensor. That usually takes 4-5 minutes before causing a rich condition. I am not sure if it's the FPR, but that will cause a rich condition as well.. When it's running rich, turn off the truck, take a look at the vacuum like that runs to the FPR. If gas is in that line, then the FPR is bad. Or take another look at the fuel pressure. It even could be something as simple as bad plug wires.. Or a stuck injector.. You can stick something solid against the injector and listen at the other end. You can hear the solenoids ticking. Or test the injectors with a test light. Could also be the TPS. Who knows..

Is it missing when it's running rich? Is it only 1 cylinder running rich or all cylinders? (Take a look at the plugs) I would eliminate each plug wire at a time to see if it makes any difference in the way it runs.. Since you cannot scan the codes, it's going to be really really difficult to determine if it's a computer problem, fuel delivery, or ignition problem.

If you're looking to swap the ECU, I have an 88 Ranger ECU left over from when I converted to mass air flow. It's a 2.9L XLT Auto 2wd. The ECU has only seen 98,000 miles and is in good shape. I have no use for it since it can't handle the camshaft I put in. I'm looking to get rid of it, but I just don't want to throw it away because it's still good.

You need to really get the codes scanned, you're shooting at ducks blind-folded..

Pete

[O.P]

Pete I am really glad this forum has someone like you on it. Let me start off from the beginning. it is an 89 with a 2.9. It was running great last fall....but then I started have problems with it dying on me. (it was a rust infested fuel tank problem).. so I put a new tank and both fuel pumps and both fuel filters....that is no longer an issue....then when I thought everything was fine, it suddenly starts running really rich. It runs rich on all cylinders, so badly that it fouled all my plugs and I could not start it. my only recourse was to put new plugs, as well as swapping out the MAP sensor, CTS, computer, O2 sensorand I think thats about it. I dunno what else it could be. I took it to a budy of mines shop, but he couldnot pull any codes off it. The scaner wouldnt read...I thought about leaving it there so he could work on it, but didnt want to get a bill for $400- on up...I was wondering if somehow the rust might have passed thru the fuel filter and clogged the injectors. I will try the idea this evening you gave me about listening to the clicking of the injectors. Any other suggestions

[Psychopete]

Originally Posted by O.P

Any other suggestions

I thought about it for a little while. I think your best bet at this point is to see if 1 cylinder is richening out or if all of them are.

If only 1 plug is getting fouled, then it's probably an issue with the injector being stuck open.

If all are getting fouled, then a sensor is not giving the ECU correct data to calculate the amout of time the injectors need to be opened for. The sensors may be good, but you might have another issue that might cause the sensor not to fuction correctly. For example, the MAP vacuum line might be cracked or the o2 wiring may be damaged. This is why I rely on scanning the codes. It can't really tell you what's really wrong, but it can see electrical faults in the circuits, which will lead you to real problem.

You don't need a scanner to scan the codes. For KOEO, I just run a nice sized wire (10ga.) from the STI (Test Connector) connector to the Signal Return (#2) and watch for the codes on my check engine light.

See here on how to retireve the codes without a scanner. Once you've done this, you'll realize how much of a waste the scanner is .
http://www.troublecodes.net/Ford/

If you still cannot get the codes, there may be an electrical fault from the self test to the ECC. Or the ECC could just be bad... Normally when they go bad, they usually don't power up, so I am more for a fault in the wiring from the self test to the ECC.

Let me know if you need any wiring diagrams. I have the year specific Ford Electrical and Vaccum diagrams for the 1988 Ford Ranger. Do not trust the Chlitons or Hayes manuals for colors. The circuits, for the most part, are the same, but the colors are way off.

Pete

[O.P]

I tried the test with the jumper wire and ohm meter. I didnt get anything, so I am assuming that the test wires are bad going into the ECU. I will check them tonight. THanks, I will let you know what I find
OP

[O.P]

All the wires look intact, I also listened to the injectors and they are all clicking away?????

[Psychopete]

Originally Posted by O.P

All the wires look intact, I also listened to the injectors and they are all clicking away?????

You need to figure out if only 1 cylinder is rich or if all are rich. You'll be able to tell from the dark deposits on the end of the spark plug. If 1 is rich, my guess would the injector is is not functioning properly, or is only firing once in a while. They make inline test lights for spark plugs to check connectivity. If all are rich, then a sensor is not functioniong correctly.

Pete

[O.P]

All plugs are rich

[Psychopete]

As a recap:
It used to run really well, but recently, all of the sudden it started acting up and runs rich. As soon I start it it will run okay for about 4-5 seconds, then it runs like crap. I checked the vacuum lines and they appear to be ok. It was running great last fall....but then I started have problems with it dying on me. (it was a rust infested fuel tank problem).. so I put a new tank and both fuel pumps and both fuel filters....

40psi Fuel Pressure

new plugs
MAP sensor
CTS (ECT)
computer - You have tried swapping the ECC?
O2 sensor

The injectors are functioning and you cannot read any codes.

All plugs are rich, so it's not isolated to 1 cylinder, which means something that globally controls the fuel is not working properly.

Wow.

Do you still have the fuel pressure gauge? I wonder if the return line is a bit plugged with a little rust, causing it to flow for 4-5 seconds, then not allowing any more fuel to return to the tank, in turn causing an increase in pressure at the fuel rail which would cause the rich mixture. Your TPS could also be telling the computer you're at WOT. Other than that, you're just about replaced everything else. It could also be the fuel pressure regulator, but I would test the fuel pressure more before blindly replacing it.

There is a way to test the TPS, but I am not sure of the procedure. I think you hook a volt meter to the wire that goes to the computer and slowly open the butterfly. The voltage should increase from some small number to around 5.5 volts smoothly.. I think.. I've never had one go out on me before..

I would certainly take another look at the fuel pressure. Sometimes it takes a little while to see a problem. Did it test it running and not running? I don't think it's vacuum related, or else the idle would be high. But I am not sure how that affects the MAP sensor if that vacuum line were leaking. It's also very odd that the codes cannot be pulled, but I suppose it's not so odd that you couldn't test it with 2 different computers. Some people do strange things to their trucks to avoid getting it repaired.. Like putting a piece of tape over the check engine light.. .

Good Luck,
Pete

[bronconut]

Originally Posted by O.P

All plugs are rich

Thats the way I bought it. I am still workng on it. Today I will check out the TPS