Alright guys, the truck in question is in my signature.

Been doing some troubleshooting, etc but first let me explain how it's all started.

4 months ago, I could pull my codes easily. No issues, whatsoever...

Fastforward to 3 weeks ago my truck started running RICH. To the point that pure black/blue-ish smoke would pour out of the exhaust pipe and you could smell it as it Idled.

Tried pulling codes, but no dice. Neither the jumper wire/paperclip method or my Equus reader would pull codes.

No CEL, nothing...

Oddly enough, it was/still running fine, the rick condition seems to have "Resolved" itself, meaning it doesn't use 1/4 tank of fuel per 30 minutes of testing. I know issues don't simply "Come and go" as they please.

Several members have pointed out that not being able to pull codes is a very bad sign of the computer failing, most probably due to leaking capacitors.

Not to be hard headed, etc.. I just have to finish troubleshooting the truck as much as possible, to rule everything else out, and give it a clear cut & dried diagnosis.

************************************************** *********
So here goes.

First off, I'm checking the PCM system. The Diode, and PCM Relay in the underhood fuse block;

*NOTE* Just putting my hand on the PCM Relay, it's physically warmer than the Horn Relay, etc.

Here's a pic for reference.



So since it's actually warm (Engine off/cold, and only the key ON) I'm suspecting a high resistance in the system at some point.

Another side note:

I have a Multimeter (Haven't used it yet) but using a battery gauge and some jumper leads, I get 12v between wire/clips for the Diode; But no voltage when touching the little "Contacts" on top of said Diode.

But if I pull the Diode out and reconnect it, it engages all the relays, etc.


That's all for now, but I'm going back out to actually use the multimeter, etc.

I'll post back in a bit.

(Thanks to Subford for the pic)

 

Check the ground wire on the driver's side core support inside.
Right behind the headlight near the top

I have had 3 different trucks that have acted like a bad computer, because this ground was corroded

 

Thanks Charlie, I'll clean it up in a few minutes...

Here's what some testing has turned up, using my dad's truck that is identical, year, etc.. Only difference in mine and his is engine and color.

-------------Michelle-----------------------------Dad's-----------

-PCM Diode: .793v-------------------------------.793v-----------KOEO
-Battery Load: 12.56v KOEO

I noticed that with simply turning the Key ON, the PCM Relay was very, very warm to the touch (About 10 minutes with KOEO)

Side note: I swapped the PCM Relay in Michelle, with the PCM Relay from Dad's truck and it did NOT get hot. Not even warm.

Did some referencing from my dad's truck (1992 F150, 5.0l/M5OD 2wd) to Michelle, in comparing the relays/numbers and here's my findings on that.

--------------Michelle----------------------------Dad's------------------

-PCM Relay: 2113 - 3 ---------------------2030 - 1
F0AB-------------------------F0AB
14B192-AA ------------------14B192-AA
************************************************** ******
-Fuel Pump: 2113 - 2 -------------------------2030 - 1
F0AB ------------------------------F0AB
14B192-AA-----------------------14B192-AA
************************************************** ******

-Horn Relay: 2113 - 3 ----------------------2030 - 2
F0AB ------------------------------F0AB
14B192-AA-----------------------14B192-AA
************************************************** ******
-PCM Diode: F0VF-14A604-AA ------------F0VF-14A604-AA
************************************************** ******

A note on the Diode's: I couldn't get a continuity test to beep with either of them.

On the PCM Relay I did a continuity test between all the connector blades on my truck, and 2 got a barely audible, and very stressed sounding beep.

So, as it stands I have tested:

CEL Bulb: Good (Visually inspected for filament breakage)
Voltage on Diode connectors in fuse block: ~ 5.5v with KOEO


Anymore input? Anything else I should test before physically pulling the computer out of the truck (Really dreading it, but will do it soon if nothing pops up as an obvious issue)

As for things with the CEL, I did one more KOEO test, and as normal, all the relays kicked and whirred, etc.. Just no test light sequences from the CEL. It's as if the truck isn't understanding "The rest of the process"

 

I'd just pull it and check the PCM. That's what I had to end up doing even though I still never had a CEL.

 

Pulling it is pretty easy if you take the tire off, and undo the bottom of the inner fender.

 

Alrighty guys here's the low down.

I pulled the computer finally and my worst fears were realized. 3 blown out capacitors.

Went to the local RadioShack and picked up 2 new capacitors and soldered them in. The closest replacement I could get was 47uf35v

They didn't have the remaining one, the 2 I could buy was 47uf16v..

The remaining one is a 10uf63v.

Closest they had was a 10uf50v. No bueno.

Here's a couple pics.

 

While they aren't local like "Phone Shack" er Radio Shack, this place has just about anything you might need in the electronics dept.. http://www.mouser.com/

Here is the look up page on capacitors http://www.mouser.com/Passive-Compon...tors/_/N-5g7r/

This looks to be what the "shack" didn't have http://www.mouser.com/ProductDetail/...Sw2IjBZZrTw%3d

 

I plugged the ECM back up to the truck, for gits and shiggles..

The truck still runs; But it's back to the drawing board with the over-fueling issue.

 

I think your better off finding a new EEC for your truck. The yard's here are FULL of 92-96 4.9's with sticks. If you cant find one locally I try and find you one...

 

I have a bad PCM,I think, and have a guy to repair them, lifetime warranty as long as you don't open the case. Let me know if you want the info.

 

I have one for a 4x4 Wess. It's from a 94