FPCM use for primary pump in return style dual pump system

[NotSure]

Currently running a single Walbro 450 on the FPCM with pwm control (returnless) and am out of pump on E85. The pump also does not seem to like running at lower duty cycle, so I plan on going full return using dual 450’s, with the 2nd pump on its own circuit and switched via boost.

I want to keep the fuel pressure sensor for logging, and the sensor circuit goes to the FPCM. The pump wiring through the FPCM is 3mm, which is approx 9 gauge. Does anyone see an issue with programming the FSCM to go full duty cycle, all the time on the primary pump, with the secondary pump on its own separate circuit? Using the FPCM would also provide a pump prime feature on initial key-on, shutting off after x seconds. This means lower battery draw with key on engine off, not that I would ever reflash without pulling fuses each time, lol. I already have the FSCM licensed. I am just not sure that the FSCM tables can be written to keep the primary pump at 100% all the time without some unforeseen quirks.

[cc-rider]

You can trigger the main pump using the green/white wire coming from the FPCM. This allows the prime to happen when key on. (Note it doesn’t prime every time the key is turned on…only if it’s been off for the while). But you can also change the prime time in the tune. Which is helpful when using return style systems. The wire then becomes on with engine crank and run. Can use this for your second pump trigger as well. But plenty of other wires to use for that too.

Also not sure what car you are running. But if it’s a Camaro. Plenty to read about this topic right here: https://www.camaro5.com/forums/showt...php?p=11161690

[NotSure]

That is good to know, thank you! This is a Gen IV truck 6.2L but it looks to be the same circuit that you are referring to.

My biggest question is if I can just take the existing wires to the fuel pump and pin it to my new pass-through to the primary pump, then tune the FPCM to operate it at 100% whenever it is on, without causing a bunch of BS faults by the FPCM. I can put all the settings at 100% duty cycle as shown, but not sure if the Desired Fuel Pressure tables for Low, Normal, and High Flow will be an issue when using a boost referenced return regulator, as the FPCM will see varying pressures as the regulator adjusts to boost?

[hjtrbo]

FPCM will throw a couple of faults but those need to be turned off. I still have my FPCM connected on a boost referenced staged return fuel system. I did as you have and set all tables to 100%. There isn't much that needs changing. All my settings are in the screenshot.

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[cc-rider]

My tuner told me he had to license the FPCM to make adjustments to it so that it wouldn’t throw code. I have no idea what this is or how to do it…but apparently it can be done. And must be done if you don’t want to deal with check engine lights.

[jdmcrx]

looks like we will be attempting to do the same objective . More info on this ?

[Alvin]

Its nice when the fuel pressure sensor is still active with a FPCM whose only purpose is to report back fuel pressure because then the ECM fires the injector properly for the fuel pressure.

When setup like this you don't do the flat injector flow rate like you normally would with a vacuum referenced line.

[ldlombardo]

relocate the pressure sensor. i put mine in an extra port on the regulator.

[hjtrbo]

Careful

There is an internal fuel pressure model in the fpcm. For the OS that I deal with under high fuel flow rates I.e. on boosted engines it will incorrectly report fuel pressure. Logging sensor volts with the following formula for delta pressure is a quick check to see if your OS exhibits this issue. (27.809*[6507.10]-20.717)+[50032.98]-[50030.98]. This formula assumes fuel pressure sensor for 2016 Holden, likely common across many models. If your OS does exhibit this issue, then consider the flatlined IFR method.

If choosing to remove the primary fuel pump and using the trigger wire to fire your new pump setup; there are DTC's that need to be switched off before removing otherwise permanent DTC's will be thrown.