Well I finally took my truck to a family member who has worked on Fords all his life and has his own garage. As I said before my check engine light stopped working period. Anyway he ran the eec rest on it with his computer and it's not throwing any codes.but occasionally it will run too rich and idle rough. He seems to think it's a clogged fuel injector. Any ideas? Also why would one of the previous owners have put a radiator for an automatic in it? Preciate any comments or suggestions.

 

Second question first, previous owner(PO) may have needed a radiator "right now", and the only one available was one with a trans cooler, wouldn't hurt anything to use it.
Maybe truck was an automatic and PO swapped in a manual, lol, longshot.

Run a can of Seafoam in the next tank of gas, that will clean out the fuel system.

I assume the family member could "talk" with the computer with OBD I reader/scanner?
But it is an odd thing about the Check Engine Light(CEL)
CEL bulbs generally outlast the vehicle.
Pin 17 on the computer activates the CEL, by Grounding it, with key on then turns it off when "self test" is done.
EEC-IV Pin diagram here: ford eec iv

Just wondering if the rich running and the CEL not working occurred in the same time frame, this could indicate a computer issue starting to come up.
It could just be a burnt out bulb, but if you were to turn on key and ground pin 17 and CEL comes on, then it would indicate a computer issue.

Between '91 and '94 ford was changing OBD I in all their vehicles to what could be called OBD I.5, from 2 digit OBD I codes to 3 digit codes, but not OBD II 3 digit codes, lol, confused.......most are.
And to make it even more confusing this updated software would often give the 111 code in error, 111 means all good no codes in memory.
MIL= malfunction indicator light = CEL

This is not meant as a dig at the family member, just a heads up since this was only an issue on a few model years and it was over 20 years ago, and these older vehicles simply do not come into shops very often, they are usually not worth the expense, DIY is the tech with older vehicles, just obscure knowledge I picked up because I have a '94 Ranger as well.

You know it is a running rich issue because......................??
Does it blow smoke with the rough running?

 

It smells rich,and smokes because of it. When I first got the truck,I did a koer test myself, I think it gave 362 as code? I tried it again one day, that's when I realized my cel a stopped altogether.

 

362 isn't an OBD I.5 code

The 300's are mostly EGR codes and a couple of engine temp codes.

Code 338 means engine is not warming up as it should, this will cause engine to stay in "Choke mode", i.e. running rich with high idle, above 900rpms
Temp gauge would stay at or below 1/4

 

When first started, engine never comes out of choke mode unless I give it some gas a few times, then it stays at about 900 rpm. I'll take off, get to work, back in my parking spot, then it has a really rough rich idle at about 500 rpm. I'll give it a little gas,then the rpm will straighten out to about 650 or 700. What's the problem? I'm at a loss about what to do.

 

I'd like to test the ecu by grounding pin 17, but don't know where the ecu is located.

 

On '94 Ranger it should be in the engine compartment driver side by the firewall on the inner fender.
It will have a plastic cover held on by 2 10mm head bolts, might have to remove fender liner to get to one of then, there is a hole to access this bolt's head

There is also a bolt that holds the wiring connector to the ECU(PCM)

This is the link to the pin numbers: ford eec iv

ALWAYS disconnect battery before working on ECU(PCM) or Airbags, failure to do this will result is a very bad day, and expensive, lol.

And if you do pull out the ECU(PCM) I would "pop the top" and have a look at the circuit board, see if any of the capacitors have leaked too much, warranty is over, disregard stickers, lol.

After connector is removed from ECU(PCM) you can hook up the battery, pin 17 should have 0v, turn on the key and it should now have 12v(battery voltage), this means the CEL bulb is getting power, it you Ground pin 17 CEL should light up(if key is still on).

Quick refresher on electricity: voltage doesn't make a light bulb light up, FLOWING voltage does.
A Light bulb is just a coil of wire with 2 external contacts, if I put 12v on one contact I would see 12v on the other contact because it is just a coil of wire and bulb wouldn't light up, but if I Ground the other contact, the 12v FLOWS to the 0v(ground), so coil of wire heats up and glows(bulb lights up).

FYI, electricity actually flows from 0v to 12v, but by the time that was discovered + and - were already determined and in the books every one learned from, and since it doesn't really matter..............why change it.

 

I checked pin 17 on connector, 0 v with key off. Power volts fluctuate with positive lead inside connector 17 with key on, negative grounded. So I believe it's getting power but cel didn't come on when grounded.