Status Update:

I changed the fuel filter (gas coming out of the old filter was brown) and resumed testing.

Pressure coming out of the forward in tank pump is approximately 4psi. The pump in the rear tank is dead, so I ignored it.

I disconnected the return to selector valve and tested the fuel pressure on the rail. It was 50 psi now when running fuel pressure test. When off, the pressure would hold and not bleed off.

I reconnected the return to the selector valve and retested getting the same results (no crazy high pressure now).

I tested the fuel pressure regulator by seeing if any fuel came out of the vacuume port -- none did. I put a vacuum on the FPR vacuum port and vacuum held. I assume the FPR is good at this point.

I started the truck and fuel pressure was 45 psi, slightly high, but I was only pulling 12 inches of vacuum so i attribute the high pressure to that.

I assumed the fuel delivery (from tank 1) was good after this point.

12 inches of vacuum is too low, I assume. I disconnected the IAC connector and restarted the truck and immediately got 17 inches of vacuum. I reconnected the IAC connector and the 17 inches of vacuum held. I re-checked the fuel pressure at this point and saw 40 psi. Looks good.

Vacuum gauge appears to act "normally". Snapping open the throttle produces a low (but non zero) drop, which then spikes to about 20 (perhaps above), to settle on 17. 17 holds steady with no wandering or floating.

I took the truck to gas station to get beer. I tested accelerating without problems.

I got the beer.

On the way home I continued to test and accelerating produced poor engine performance. This means the problem is not resolved. When accelerating beyond a certain point the engine would bog, and I thought I heard a metal ping (or bang?) at this point. I continued to drive, and by the time I got home this problem had mysteriously dissapeared again.

I drank the beer.

 

Your engine should die when you disconnect the IAC. If it doesn't, then your idle isn't set right. Disconnect the IAC again with the truck running. Slowing turn out the Idle set screw JUST until the engine dies. Hook your IAC back up, now the truck's computer is controlling the idle, not the set screw.

 

Ray,

This is interesting. Before, when I was unplugging the IAC I tested it as follows:

I disconnected the IAC and then I started the truck. The truck would run like this for some reason. Today, when I tried testing the IAC I started the truck THEN unplugged the IAC -- and it died. Interesting. Is the computer compensating for something?

 

Status update:

I checked codes tonight.
18:SPOUT circuit open or spark angle word failure
18: (?) IDM circuit failure or SPOUT circuit grounded
63: TP circuit below minimum voltage

I'm assuming the code 18 is something you get if you disconnect the idle air control (IDM = IAC?), but I haven't investigated it.

Does anyone happen know the proper way to clear the codes so I can start fresh? Do I just unplug the batter for a few minutes?

 

IDM = Ignition Diagnostic Monitor.

Code 18 is telling you the computer isn't getting the correct signal from the distributor pickup (aka stator, a hall-effect device), I think dark green/yellow-stripe wire from the inside of the dizzy, through the ignition module (if TFI) and to the computer. This is how it knows when the #1 cylinder has passed by, this functionality was replaced with crankshaft position sensors in later years.

This site may help you:

Fuel Injection Technical Library

Disconnecting the battery for ~10 minutes should work to clear codes, can also unground the STI (or STO, I forget which gets grounded) while it's spitting codes if counting blinkenlights/using a meter. (I think that works, anyway, don't remember for certain.)

 

Oh man, now I have codes on stuff that I wasn't even messing with.
Though, at least, a distributor problem could certainly cause my symptom.

It seems strange that the computer wasn't getting any spark signal and yet the truck managed to run flawlessly. I think I'll clear the codes and keep it local for a while and see if they start returning. if I throw another distributor code I'll try to diagnose if it's the magnetic pickup.

I'm sorry I'm not sure what TFI is. My truck is "EFI" I believe -- if they are even similar acronyms.

 

lol. If you have an EFI speed density truck, than you have a TFI module. The TFI module is the microchip that is plugged into your distributor. There is a large flat plug that plugs into it at the distributor. You can take the TFI module out and have it tested at Autozone. Mine was bad a few weeks ago. I was having poor performance and starting issues. Aparently my TFI module was going bad, but what killed it was the magnetic pick-up trigger. I had to replace both the trigger and the module to get my truck to run.

To replace the magnetic trigger you have to remove the distributor from the engine. Punch out the spring pins holding the cam gear and guide bushing on the shaft. Then slowly pull the shaft out of the dist. housing. (i had to tap mine with a small hammer because of carbon built up inside) Then you can get the trigger out, and install new trigger. Just reverse the process. I did take off all the spark plug wires to make cap and dist. removal easier. So I went through the process of setting TDC, and re-installing the wires in firing order. You may choose not to do that if you can get the dist out with the cap still attached to the wires, but I felt that I couldn't.

 

https://www.google.com/search?q=ford...AYWW8gTXoIHYDA

 

OK, certainly my truck is TFI. I'll clear the codes, and rip out the TFI module and take it over and have it tested if I have time tonight.

I guess this is like everything else; you have to learn all the acronyms.

Thanks guys.

 

Yup, I didn't know what a TFI module was until mine went bad a couple weeks ago. Ive been a chevy guy all my life so all this Ford stuff is new to me also.

 

Your codes, which ones are from each of:

KOEO
CM
KOER

Diagnostic routines are sometimes different, it depends.

 

ctubutis,

My codes are from "CM" i believe (Constant Memory, right?). I didn't initiate any special test that I'm aware of. The truck was not running while I pulled the codes.

I did clear the codes last night, and then ran the truck for a bit and rechecked and got nothing. I'm SURE the problems will resurface, but I wanted to perform a sanity check of sorts; clear everything (because I had been messing with connectors while it was running), drive the truck, and see what comes back.

 

It's not a special test, KOEO and CM (yes, continuous memory) codes are separated by blinkenlights.

Please read the instructions and learn about what it is you're doing.
Fuel Injection Technical Library » How To Run a Self-Test

That's good, I've taken the same approach before.

If you post again in the future with codes, be sure to specify what codes come from what source (e.g. engine off, CM, engine running). The diagnostics are VERY specific (in capital letters and bold type) and say, for example, "deal with this other thing first, then come back here and do this if necessary."

 

The codes came from CM, not KOEO.

 

Assuming Code 11 for KOEO, any codes except for 15 in CM, the shop manual says:

CONTINUOUS MEMORY indicates a fault. DO NOT REPAIR THESE CODES AT THIS TIME! KEY ON, ENGINE OFF and ENGINE RUNNING codes must be repaired first.

OBD1 is very particular, it's not really like OBD2.

The SPOUT circuit is used for advancing the ignition timing, the engine will still run with that wire disconnected and, in fact, you first disconnect that wire (unplug the jumper plug) when setting the base ignition timing.