Stalling / No start / Tach Jumping w/ key on / code 14
This truck is Haunted!!!
Hello All....
I have an 1989 ford F-150 2-wheel drive
5.0 5-Speed Manual. Dual Tanks.
The truck was running just fine. It started to miss and run rough one day.
I noticed the Tach was jumping all over. Eventually it stalled. Sometimes it starts, sometimes not……I get a code 14 (pip).
I replaced the Ignition module and it seems ok …then it started again….so ..I replaced the distributor. (Hall Effect Sensor)
The exact thing happened again.
I took everything back…went to another store and bought a new distributor and module…..did everything AGAIN….
Any way ..I have the same problem????
and a Code 14.
I checked the wiring per the Haynes book
The PIP voltage is 1.8 to 1.2 AC should be 3.0 to 8.5AC (Position 6 dark blue wire PIP OUT).
I also measured the resistance it reads 14,000 ohms between pin 6 and pin 56 on the PCM connector.
The resistance of that wire seems OK.
PIN 1 resistance to ground reads .3 ohms …should it be more than 10,000 ohms? If this is a gnd then .3 Ohms would be correct
>>>>>DAY 2<<<<<<
Replaced the coil ..it was badly rusted. The old coil checks OK….per the book.
PIP voltage is 5.5 volts ac cranking
SPOUT voltage is .005 cranking
Spout connector to PCM Pin 36 is .3 ohms
Everything reconnected.....
I turned the key on …and the tach was jumping wildly…also the fuel pump relay was clicking....The fuel pump would not turn off untill I turned the key to off.
Previously tested the pump and the pressure was 35 PSI
When the vacuum line was disconnected from the regulator the pressure increased. That looks normal for fuel pressure.
I traced out the harnesses and ended up removing the PCM unit. There was some corrosion on the case at the bottom connector side. I removed the covers and the circuit board looks fine. Obviously some water had leaked at one time.
So I will clean the pins and sockets on the connector and have it ready to install.
>>>>>>DAY 3<<<<<<<<<<<<
Cleaned all the grounding points.
Replaced the two relays ......Fuel and PCM power....
Re-assembled everything and started with the diagnostics and voltage readings again....

TEST RESULTS

Fuel Pressure 35 Lbs.
Vacuum at idle 20
Ing Coil Voltage 12.10 VDC
Coil Primary .6 Ohms
Coil Secondary 9.26 k Ohms
Primary circuit (coil neg. – ICM Pin 2/Tach) Continuity OK
Tach Neg Coil to ground 19K Ohms

ICM Pin 1 Run Position 4.8 Volts
ICM Pin 2 Run Position (Module Supply Voltage) 12.4 Volts
ICM Pin3 Run Position 12.4 Volts

ICM Pin 3 Start Position 12.4 Volts
ICM Pin 4 Start Position 12.4 Volts
ICM Pin 1 Start Position 4.8 Volts

Tach Neg Coil to Ground Test light Cranking Position Flashing

PIP Sensor current VAC Cranking 5.5 VAC
SPOUT Sensor current VAC Cranking 5.6 VAC
****
I turned the key on …and the tach started jumping wildly…bouncing up to 4,000 RPM. The fuel pump would not turn off untill I turned the key to off.
as before. Turned off the key .......Turned on the key... Fuel pump hummed for 2 seconds and shut off......hit start ...started right up...ran for about 10 minutes...and stalled out.
Engine light .....Code 14

Can anyone point me in the right direction?
This is the strangetd thing I have everseen...
Thank you for looking..
-Anthony

 

The reason the fuel pump is not cutting off is the computer thinks the engine is running. The computer controls the fuel pump relay. When the key is first turned on, it primes the pump and then stops. It is now waiting for an indication that the engine is running. It gets this indication from the pip signal from the distributor. When the computer knows the engine is turning, it will activate the fuel pump relay.

Apparently your PIP signal line is intermittent. You are getting a chopped up signal from somewhere, and that is why the tach is reading and the computer is turning the fuel pump on.

One thing you could do is find the pin at the computer that the PIP signal comes in on. You could see if you can extract that wire/pin from the plug, and then try turning the key on with it plugged back in the computer. If everything calms down, you know the problem is external to the computer.

If it's external, the next thing you can do is hook everything back up, and turn the key on. Then go from the computer to the dist, wiggling the plugs and wires. See if there is a certain point where messing with the wiring makes a difference in the fuel pump clicking and the tach going crazy.

P.S. Some of these signal wires are shielded. Sometimes the end of the wire where the shield stops can get damaged, and the shield will short to the signal wire. Check the shield out and make sure it's ok.

 

Thank You for the reply.
I am looking for a replacement Computer. In the meantime i will check out the shielded wires.
-Anthony