1G 1G MPI Control Relay

[all black 4G63]

Would like to know if it will cause any damage to the ECU if the MPI relay is eliminated and switched B+ is ran to pin 107 (C-59) of the ECM?

I would also be eliminating all factory fuel pump control circuits (pins 56, 13, and 108 at the ECM) as I would run a HP pump on a separate replay and switch?

I am assuming pin 108 (C-59) is used as a crank sense to enable fuel pump control after the key is rotated from start to run and an RPM signal is obtained? I assuming the ECM does this by applying ground to pin 56 (C-60) after the key is rotated from "start" to "run"?

I am also assuming the ECM applies ground to pin 63 (C-60) to close the MPI relay contacts when IGN B+ is applied to pin 110 (C-59) when the key is switch to KOEO?

I have attached a photo of the MPI Circuit out of the 1992 Laser/Talon Electrical service manual. I am working with a 1992 TSI manual AWD

Thank you for your input and assistance.

 

[lasthope05]

If you are using a stock ECU you need to retain the power side of the MPI relay as the ECU needs to control the power down in order to be able to modify/save any tunes/changes. If you are using an aftermarket ecu, it shouldnt matter.

The fuel pump control can be run on a standalone switch if you wanted, but if you were running a stock ECU I would just allow the ecu to control it.

 

[all black 4G63]

Thank you for the information

 

[roukyweal20]

You can think of a relay as being just like the light switches in your house, but with one big difference: Instead of turning on the light by a little lever or button, in a relay you turn it on by sending it a small amount of electricity Tutuapp 9Apps Showbox.