2003 fault codes and failed replacement fca?

[mweiman]

Worked on an 03 last week that had a p0088 fault code and would start and die and ramp up rail pressure. Replaced the fuel control actuator, he drove it for a day and all was good, I monitored rail pressure versus desired pressure after replacing fca and they stayed consistent. The next day he said it sounded like the rail pressure was ramped way up again, he drove down the road a ways and then it would only idle, no throttle response. Checked it out last night and rail pressure was running around 25,000 psi when desired was about 5000 psi. P0088 was back and a p2121. There was also I think p2128 which was there the first time I looked at it and would not clear out, although he said it had been for quite a while and throttle always worked ok. Could there be any relation between the dead pedal, rail pressure and APPS codes. My other question is with the FCA appearring to be stuck open could a failing CP3 be putting debris into the FCA to make it stick? Rail pressure seemed to "hunt" around a little more with the FCA plugged in than when I unplugged it. Also 230,000 miles onthe truck. Thanks for any help.
Matt

 

[mweiman]

Does anyone know if a CP3 was failing if it could plug an fca? Or is there a way to test the electrical signal to the fca? It did not seem to change by pulling or wiggling the plug.
Thanks

 

[cerberusiam]

Does anyone know if a CP3 was failing if it could plug an fca?

It sure can. The internal pump on the CP-3 is before the FCA. If the cavitation is beating the gear rotor pump to death it will have FOD all the way to the injectors.

 

[mweiman]

That was my train of thought. It was still showing 25,000 psi at idle. Is there any shared circuit between the APPS and the FCA that could be pulling down the communication down to the FCA? Maybe it is just a coincidence that both are failing at once.
Thanks,
Matt

 

[mweiman]

That was my train of thought. It was still showing 25,000 psi at idle. Is there any shared circuit between the APPS and the FCA that could be pulling down the communication down to the FCA? Maybe it is just a coincidence that both are failing at once.
Thanks,
Matt

 

[cerberusiam]

Yes, an electrical issue in the system somewhere will do what you describe. Disconnect the batteries and drain the capacitors while checking all connections and see if that helps.

 

[Bob4x4]

Turn the ignition on.
Disconnect the Electronic Fuel Control Actuator connector.
Connect an incandescent test light across the Fuel Control Actuator driver pin and the Fuel Control Actuator return wire at the fuel control actuator connector.
Observe the test light.
The ECM will perform a self test of the circuit which should momentarily flash the test light brightly, one time, approximately 20 seconds after being connected.
NOTE: Compare test light brightness to that of a direct connection to the battery.