medrick

So this issue came out of nowhere when i was driving to work last Friday. Was running just fine and then all of the sudden sputtered and died like it was out of fuel even though I have almost a half tank.

I have no prime at the fuel pump when i turn the key on. I have verified the pump, IFS switch, CCRM, FPDM and PCM are all good/not the issue.

Tested the pump by applying 12v to pin 10 in the FPDM plug and the pump kicked on and worked.

Tested the resistance of the IFS switch (.5 ohm's) and checked for voltage of the green/yellow wire (12v)

Tested the FPDM by swapping out 2 brand new ones with no change.

Tested the CCRM by swapping in a different one with no change and then putting mine in a buddies car and his still ran and primed.

Tested the PCM by putting in a different one and turning PATS off in the tune with no change.

Here is where it gets interesting. If i apply 12v to the pump directly from a battery to prime it and then plug the FPDM back in, i will start and then stay running.

So i believe the issue lies within the wire that goes from pin 80 in the PCM to pin 1 in the FPDM harness plug because i think it had no voltage when i turn the key on (assuming this is the wire/pin that tells the pump to prime)

Any thoughts?

uberstang1

First step when you thing you have a fuel issue is to get a gauge and check the fuel pressure at the rail. But IMO this sounds like the fuel pump relay which is part of the CCRM.

Chris03 GT

You may have a problem in the ignition switch.

cliffyk

PCM pin 80 is a PCM output, a variable duty cycle signal to the FPDM. If the d/c is 5 to 50% the FPDM will drive the fuel pump to 2x that value, I.e. 10% to 100% of its capacity. A duty cycle of 67.5% to 82.5% command the FPDM to shut down the fuel pump. The PCM will not output any other duty cycle signals.

The FPDM reports status back to the PCM on pin 40, again a variable duty cycle signal. A 50% d/c reports that all is "OK", 25% means the FPDM did not receive any, or an invalid, d/c signal from the PCM. 75% indicate the FPDM has identified a fault in the circuits between the FPDM and the pump.

The frequency of these signals is only 1 Hz so 5% to 50% = 50 to 500 ms, 25% 250 ms, 75% 750 ms.

The PCM will not command the fuel pump to run, after the initial prime, if it does not receive a signal from the CKP (Crankshaft Position Sensor) so that would be something to check--here is the full description of how the electronic returnless fuel system works.