How to handle Supra 9V-12V fuel pump ecu ?

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Halfwalker
Posts: 18
Joined: Sat Dec 07, 2019 1:44 am

How to handle Supra 9V-12V fuel pump ecu ?

Postby Halfwalker » Thu Dec 12, 2019 10:39 am

I have a 94 TT Supra that will be getting some Elite 2500 goodness shortly - UPS is delivering on Fri ! In the planning for the wiring, I have a question about fuel-pump control ...

The Supra has a fuel-pump ecu to control the pump. It's fed +12V via the main EFI relay, and feeds either 9V or 12V to the pump itself, enabled via a single input from the main ecu. The stock ecu has its own algorithms to decide when to bump from 9V to 12V, depending on RPM and probably other factors.

Haltech provides several sample maps for the Supra, but they all just seem to use the fuel-pump function and a DPO as a regular control signal - it's either on for the car running or off when it's shut down. This is a fairly typical setup for Supras with standalone ecus. However, I would prefer to replicate the oem control, enabling the 9V-12V bump as needed. To do that, I'm figuring on :

Disable the regular Fuel Pump function
Enable a Generic Output using DPO4 named FuelBUMP as a state output
Edit the Generic Output table :
Set axis 1 to RPM
Set axis 2 to Manifold pressure
Fill table with axis 1 = 0 up to say 4000 rpm and =1 above that, and axis 2 = 0 for MAP up to say 7psi and = 1 above that

Would this be the right approach ?

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HaltechMatthew
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Re: How to handle Supra 9V-12V fuel pump ecu ?

Postby HaltechMatthew » Thu Dec 12, 2019 10:40 am

You can do that if you want, but just switching it as we do has worked for the 1000's of people.

Halfwalker
Posts: 18
Joined: Sat Dec 07, 2019 1:44 am

Re: How to handle Supra 9V-12V fuel pump ecu ?

Postby Halfwalker » Wed Dec 18, 2019 1:58 am

True .... I'm assuming that you connect the fuel-pump control DPO5 to Supra ECU pin A22 (FPC) ? That's the pin that controls the fuel-pump ecu to switch between 9V and 12V.

That fuel-pump ecu input is a 5V input. Isn't the DPO putting out 12V ? DUHH, my mistake, it's a grounding output.

Control on the FPC pin for the fuel pump is :

    +12 - Starting and high engine load
    +9V - Low load and idling
Given that the fuel pump ecu and power to the pump is controlled by the main EFI relays which are controlled by the Haltech ECR pin A25/DPO6, is that fuel-pump control actually needed ? One could just tied that Supra harness pin A22/FPC to +12V so the pump runs at full speed all the time, but only while the master relay is on.

Do you have pin-matching map available for the Supra plug-n-play harness ? I've seen the I/O report for the Supra maps which show which Haltech pin is used for which function, but I don't know which harness pin they map to.

Rallly1
Posts: 16
Joined: Sun Nov 10, 2019 8:10 am

Re: How to handle Supra 9V-12V fuel pump ecu ?

Postby Rallly1 » Sat Feb 13, 2021 12:43 pm

Hello! I to have the elite 2500 with P&P harness to my MKIV Supra, and I am trying to figure out the best way to wire my dual pumps into it. Can you give me some help here Halfwalker?

Jay

Halfwalker wrote:True .... I'm assuming that you connect the fuel-pump control DPO5 to Supra ECU pin A22 (FPC) ? That's the pin that controls the fuel-pump ecu to switch between 9V and 12V.

That fuel-pump ecu input is a 5V input. Isn't the DPO putting out 12V ? DUHH, my mistake, it's a grounding output.

Control on the FPC pin for the fuel pump is :

    +12 - Starting and high engine load
    +9V - Low load and idling
Given that the fuel pump ecu and power to the pump is controlled by the main EFI relays which are controlled by the Haltech ECR pin A25/DPO6, is that fuel-pump control actually needed ? One could just tied that Supra harness pin A22/FPC to +12V so the pump runs at full speed all the time, but only while the master relay is on.

Do you have pin-matching map available for the Supra plug-n-play harness ? I've seen the I/O report for the Supra maps which show which Haltech pin is used for which function, but I don't know which harness pin they map to.

Halfwalker
Posts: 18
Joined: Sat Dec 07, 2019 1:44 am

Re: How to handle Supra 9V-12V fuel pump ecu ?

Postby Halfwalker » Wed Mar 10, 2021 5:32 am

I don't have the PnP harness, nor am I using dual pumps. I'm using the stock fuel-pump ecu with a soon-to-be-upgraded pump.

For your dual pumps, I would run a fused wire directly from battery to the rear, through a pair of relays (one per pump) and use the Elite DPO to trigger the relays.


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