Fuel Pump Driver Module

Hppyd · Sep 25, 2017

Here goes. This is my first attempt at a forum and asking for help. I have a 2004 3.9l. It starts acting like its out of gas, stumbling and popping. I can turn it off and back on then runs good for very short distance. I was able to get home by doing this. The CEL comes on and the code is for the fuel pump driver module. I purchased a brand new one and cleared the code. Still have the same problem and code. Please give me an idea of what to look for. I figured it would be a bad fuel pump.

wmburns · Sep 26, 2017

It would be better to post the full DTC code. There are 1,000's of them and they each have a story to tell.

But in general:

Bad fuel pump
Bad fuel pump driver module ground
bad trunk mounted IFS switch
bad CCRM
bad fuel rail pressure sensor (FRPS)
disconnected or leaking FRPS intake vacuum reference line.
kinked or blocked fuel line.
bad PCM

If this were my car the tests to do:

Confirm that the FRPS intake vacuum line is connected and leak free. Check the line for evidence of raw gas.

Confirm there's key on +12 volts at the trunk mounted IFS switch. Use a KNOWN good ground.

Measure the fuel pressure with an external gauge. Best to compare the measurement to what the PCM believes the FRPS value is.

But how to find out what the PCM "thinks" the FRPS value is? Here's some information on an affordable Windows based ODB2 scanner.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

Hppyd · Sep 26, 2017

wmburns said:
It would be better to post the full DTC code. There are 1,000's of them and they each have a story to tell.

But in general:

Bad fuel pump

Bad fuel pump driver module ground

bad trunk mounted IFS switch

bad CCRM

bad fuel rail pressure sensor

disconnected or leaking FRPS intake vacuum reference line.

kinked or blocked fuel line.

bad PCM

If this were my car the tests to do:

Confirm that the FRPS intake vacuum line is connected and leak free. Check the line for evidence of raw gas.

Confirm there's key on +12 volts at the trunk mounted IFS switch. Use a KNOWN good ground.

Measure the fuel pressure with an external gauge. Best to compare the measurement to what the PCM believes the FRPS value is.

But how to find out what the PCM "thinks" the FRPS value is? Here's some information on an affordable Windows based ODB2 scanner.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

Thank you. I'm new at this and didn't think to list the code. The code is:
P1233 Fuel pump dvr mod disabled/off line.

imp · Sep 26, 2017

@wmburns
Am I correct in thinking this would be a returnless fuel system, having the Fuel Pressure and Temperature Sensor, as well as the Pump Driver Module, which I believe to be absent on return-type systems? imp

Hppyd · Sep 27, 2017

imp said:
@wmburns
Am I correct in thinking this would be a returnless fuel system, having the Fuel Pressure and Temperature Sensor, as well as the Pump Driver Module, which I believe to be absent on return-type systems? imp

I'm thinking you are correct. It is the oem system

wmburns · Sep 27, 2017

Hppyd said:
The code is:
P1233 Fuel pump dvr mod disabled/off line.

>>From Ford service manual
P1233 - Fuel System Disabled or Offline

Inertia fuel shutoff (IFS) switch needs to be reset
Open FPDM ground circuit
Open or shorted FPM circuit
Damaged IFS switch
Damaged FPDM
Damaged PCM
Also for Escort/Tracer and Mustang:
- Open FPDM PWR circuit
- Open B+ circuit to constant control relay module (CCRM) pin 11
- Open ground to CCRM pin 18 (Mustang)
- Damaged CCRM

The PCM expects to see one of the following duty cycle signals from the FPDM on the FPM circuit: 1) 50% (500 msec on, 500 msec off), all OK. 2) 25% (250 msec on, 750 msec off), FPDM did not receive a fuel pump (FP) duty cycle command from the PCM, or the duty cycle that was received was invalid. 3) 75% (750 msec ON, 250 OFF), the FPDM has detected a fault in the circuits between the FPDM and the fuel pump.
<<

Here's some information on how to perform voltage drop tests to confirm the ground in the trunk ability to carry large current. Measure the voltage from the trunk ground to battery negative with the key on.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

imp · Sep 27, 2017

@wmburns
When my returnless system Fuel Pressure and Temperature Sensor failed, I began thinking about possible consequences. PCM relies on the FPTS data to prompt the pump driver module, which in turn adjusts pump output to maintain constant fuel pressure regardless of flow rate demand. I got no noticeable symptoms other than the CEL and DTC for failed FPTS. Got scared anyhow, fearing being dead in the water somewhere.

Surprise! Ford thought of that possibility. Failed data from FPTS causes PCM to run pump at maximum voltage, thus maximum fuel output. That results in pressure somewhat higher than normal, ~ 10 psi or more, the pressure being held to that "emergency operation" level by a relief valve at the pump which dumps the excess volume back into the tank.

Driving with a failed FPTS will result in higher fuel consumption and emissions, probably additional emissions-related codes too, but at least yer not stranded! imp

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