Hello everybody. I thought I could figure this out on my own. Now I have to ask. I have a 1984 F150 I6 that had multiple problems. The exhaust smelled horrible, and the truck got about 6mpg. The check valve was severely rusted and dumped exhaust into the engine compartment which then dumped into the cab. The truck could barely get out of its own way. The local mechanic said the first thing that needed to be done was replace the carb because it was pouring gas into the engine. He said it would be about 900 to replace all said and done then he could figure out what else was wrong. I said I would do it myself. What I have done:

replaced the AIR check valve (under the carb)
Rebuilt carb, same as origional
Remade and replaced hot air pipe to choke
New cap, roter and plug wires
New PCV valve

Now the truck hesitates (bogs down) going up a hill or down the highway for periods of time then kicks back in and accelerates hard. This can happen with no movement of my foot on the gas pedal. I purchased an actron CP9015 code scanner and tried to get the thing to give me some codes. When I turn the key on (engine off) the code reader just stays lit with the buzzer on.

I thought that the code scanner would help guide me. Any thoughts.

Craig

 

Do you have a DVOM or test light? If so, might try to pull codes by counting blinkenlights.

This should get you started:

Ford Fuel Injection » How To Run a Self-Test

 

Thanks for the link. I do have a carburator and a mechanical fuel pump so probably a little different but i imagine the test is the same.
I initiated the "self test" as instructed- No clicks
Then I restarted with the Multi-meter hooked up (white/red stripe wire) and the multi-meter just pegged itself at 0ohms, no movement.

The white redstripe wire looked like the correct one according to the picture.

What should I try next?
Thanks Craig

 

Is it drivable? If so, take it to an auto parts store and have them try to pull the codes; I use O'Reilly's cuz they can print out some helpful stuff related to any error codes they may fine.

This is an OBD-I system which has got 3 sets of codes:

KOEO
CM
KOER

With any luck, the operator of the scanner tool will know how to use it correctly....

 

Thanks. I'll take it there tomorrow, and let you know what happens.

 

OK. O'Reillys guys got their scanner, and it said " no response from vehicle"

I'm wondering if there is a short in the harness. Is there a way to get the codes from the computer from under the dash? Is it possible that the computer is kaput?

 

Is the O2 sensor still connected? How about the temperature sensor for the computer, which is located in the thermostat housing? Is the MAP sensor still connected? It is located by the battery. Are the wires which go to the carburetor [besides the choke wire] still connected?


If any of these are not connected, the computer will be "blind" and will automatically lock the timing and set the carburetor to its richest setting. This is referred to as being locked in the "safe" or "limp home" mode. This is to protect the engine, but results in poor performance and excessive fuel consumption.

 

Yeah, but, David, he should still be able to pull codes from it even with all the sensors disconnected.

It is theoretically possible for a computer to be totally dead but I more suspect corroded connections and/or a lack of power to it and/or broken wires in the harness from computer to self-test plug (where you plug in the code reader).

I don't have the wiring diagrams that cover this configuration.. I can probably look in the shop manual that covers the EEC-IV diagnostics and there *might be* a diagram showing the computer's pinouts and which pins are supposed to be hot/grounded and when, but it's definitely not going to show the vehicle-specific wiring that supplies that stuff (e.g. power relay and its location, how it gets energized, whatever).

I would *guess* that the computer's power comes from one of the kinda-thick wires at the starter solenoid with a fusible link in it but that's only an educated guess... what its color might be, what size fusible link it contains, etc. are things I have no idea on...

 

Hmmm... there is a relay for the computer. It is located under the dash near the ash tray. It "went out" on my son's 1984 with the same engine/system while he was away. A local mechanic diagnosed it. As I remember it, with the bad relay, the engine still ran, but performed poorly.


This would be the little bugger: http://www.rockauto.com/catalog/more...254&cc=1121432

 

OK. So my temp guage has not been working (really Im not trying to withhold information). I went to Oreilys and got a new one. Cant get the old one out but I connected the new one and grounded it (dont think it needs that but did anyways) Then I figured I would try to pull the codes again. Nothing. Grounded the single wire to the battery instead of the code reader and it worked.

22-MAP signal
51- ECT signal too high
53- Throttle position too high
68 Idle tracking switch (grounded)

When I get the new temp sensor in that should take care of 51. Ill get a new MAP sensor for 22.

Would 53 be a stored code from before the carb was changed with a new Throttle position indicator?

What can I do for 68?

Thanks guys.

 

The stored codes are in the CM portion - after KOEO codes are displayed, so YOU are the only one able to tell US if it's a stored code or not.

I have no idea about 68 because, as above, I don't know from which of the three sections it's coming. A little more info, please.

When I pull codes, all I do is connect the wire in the single, gray connector to a good ground and then proceed....

 

Tried it again this morning and it took a bit of coaxing to get the codes again, something I'm doing or a sign of a bigger problem I suppose. First question, When I turn the key to on at the beginning of this procedure, do I press the clutch in at the start then let go or hold it in the whole time?

So KOEO codes:
22
51
53
68

Then CM codes
22
51
61
63
53
13

Headed to Oreillys to get a socket that fits the temp sensor.

Thanks again for the help ctubutis and 1986f150six

Craig

 

Changed the temp sensor. Started the motor up and I noticed a wire, below and behind the oil pressure switch, attached to the engine block that was loose. Stopped the motor and tightened that sucker up. There was a black wire from this point to the body, grounding wire, and an orangish wire going into the wiring harness.

Drove around the block, temp gauge now at least hits the "C" but same symptoms. Pulled codes again with the same codes.

Ill get a vacuum pump and check the MAP unless OReillys can do it.

I have no idea what the Idle tracking switch is??

Anyways, that where I am with this project.

Thanks, Craig.

 

Craig,




Send a PM to Wyowanderer. He is knowledgeable about this system as he lives in an area requiring emission testing. Wait, I believe one has to have 25 posts before being able to PM. I'll do it for you and ask him to look into this thread.


David

 

Thanks David.