What Is The Fuel Pump Controle Modual

[mark morris]

Ok, I just installed a power fc into my R33 GTR and it would not run the fuel pump, but put the stock ecm back in and bang the fuel pump runs again??? upon a great deal of head scratching and finally getting a wiring diagram i found that the fuel pump relay is negativly switched by the ecm. Which both ecm's were doing fine.

what I then found is that the negative side of the fuel pump is also switched. this done by the fuel pump control modual, this is controled by what apears to be the ecm. the stock ecm puts the fuel pump to ground via the FPCM at the same time as the fuel pump solinoid is enigised.

but the power fc dose not control the negative side of the pump at any stage. There for the circuit is not complete and the pump dose not work.

To combat this I have directly grounded the negative side of the pump so when the soliniod is enigised the pump is on. This seems to work fine.

Ok, the questions I have is:

# what is the FPCM and why is it there? (dose it mesure current draw accross the pump as a safty mechanism for a failing pump, wouldn't a simple fuese do this?)

#Is it Ok/safe to by pass it like I have?

#why dose the stock ecm work with it and the power fc not?

I will list mods I have just done from stock engine, just in case ive missed somthing (notice higher flowing fuel pump).

*n1's

*full exaust and dumps

*pods

*FMIC

*z32 MAFS

*pon cams

*cam gears

*700cc injectors

*rail

*regulator

*sard 700hp intank direct replacment pump

*Power FC

And a pic of the wiring diagram for reference.

Regards, Mark.

[Sydneykid]

You have the wrong model of Power FC for your car.

The FPCM controls the voltage supplied to the fuel pump. This changes the amount of fuel pumped to the engine according to how much fuel the engine needs. For example at idle the fuel pump voltage is lowered, so that excessive fuel is not sent to the engine and then returned to the tank. This avoids overheating the fuel by pumping it around and around, to and from the hot engine bay when it is not needed.

Cheers

[mark morris]

You have the wrong model of Power FC for your car.

The FPCM controls the voltage supplied to the fuel pump.  This changes the amount of fuel pumped to the engine according to how much fuel the engine needs.  For example at idle the fuel pump voltage is lowered, so that excessive fuel is not sent to the engine and then returned to the tank.  This avoids overheating the fuel by pumping it around and around, to and from the hot engine bay when it is not needed.

Cheers

<{POST_SNAPBACK}>

ok thanks SK, would it be ok to use the FPCM with a larger pump? as the voltage requirements would be different I guess?.

Also the pfc i have says on the hand controler the porg.ver. is RB 26 DETT, power fc ver 8.04A fc commander3 ver 5.01a. this all appears correct. and on the box it says nissan gtr bnr32/bcnr33 and on the paper work it says gtr33l020-1226. Dosn't this sound correct for an r33gtr v-spec?.

[Sydneykid]

ok thanks SK, would it be ok to use the FPCM with a larger pump? as the voltage requirements would be different I guess?.

Also the pfc i have says on the hand controler the porg.ver. is RB 26 DETT, power fc ver 8.04A fc commander3 ver 5.01a. this all appears correct. and on the box it says nissan gtr bnr32/bcnr33 and on the paper work it says gtr33l020-1226. Dosn't this sound correct for an r33gtr v-spec?.

<{POST_SNAPBACK}>

Pump Wiring - You really should look at upgrading the wiring (with a relay and a separate power supply direct form the battery) if you are using the fuel pump to its rated capacity. This will give you some overhead if you ever need it. The downside is you will get hot fuel in traffic as more fuel gets pumped around than the engine needs. If you don't need the fuel pump's full capacity, then retaining the factory ECU controlled fuel flow is a good idea.

Power FC - I believe by grounding the negative side of the FPCM you may have over ridden the voltage control from the ECU. You really need to check the ECU pinouts. Pin #104 and Pin #106 are the FPCM voltage outputs, it sounds like maybe you have only one of the 2 working. I would check them with a multimeter at the ECU plug with both the standard ECU and the Power FC at idle and with some load on the engine.

Hope that was of some help

cheers

[mark morris]

Thanks I have tested the pins 104 and 106 yesterday and they have no voltage at any stage, as I think this side of the power fc dose not work. do they ever on the r33 version?

[Scooby]

Pump Wiring - You really should look at upgrading the wiring (with a relay and a separate power supply direct form the battery) if you are using the fuel pump to its rated capacity.  This will give you some overhead if you ever need it.  The downside is you will get hot fuel in traffic as more fuel gets pumped around than the engine needs.  If you don't need the fuel pump's full capacity, then retaining the factory ECU controlled fuel flow is a good idea.

cheers

<{POST_SNAPBACK}>

does that mean the right model of PFC will work with the FPCM in the same way the stock one does?

[Sydneykid]

Thanks I have tested the pins 104 and 106 yesterday and they have no voltage at any stage, as I think this side of the power fc dose not work. do they ever on the r33 version?

<{POST_SNAPBACK}>

Does that mean only pin #18 has output?

The R32 and R33 Power FC's are the same, and R32GTR's have Pin #104 and #106 the same as R33GTR's.

On R32GTST and R33GTST only pin #104 is used as they only have 2 fuel pump voltages.

cheers

Edited October 24, 2005 by Sydneykid

[mark morris]

yes only 18 dose any thing that i can see any way, that is groud the fuel pump solinoid.

[mark morris]

I think im gonna just delete the FPCM circuit and have the pump running at full voltage all the time when switched by pin 18, I will run 4mm wire in stead of the 3mm already there, going from batery to the pump and then to ground. using the original relay and switching circuit.

Dose any one see any problems with this except for the bit of extra fuel circulation at idle.