Hey all you Squirters,

I finally finished the new wiring harness for the ECU & relay board on my MS install.

Did any of you have to bypass the stock Fuel pump relay to use the MS relay board's fuel pump relay?

Initially for fuel pump control I ran the #19 wire from the white connector on the stock relay board to the MS ECU.

Now that I'm using the MS relay board, my fuel pumps not coming on when connected to it. Fuse checks out, and if I run the single ground wire for the FP to engine ground instead of the MS relay board - FP runs fine.

Any thoughts?

TIA

Gerard

I'm not following your description. I'm using the MS relay board and no problem

Dave

On mine, I left it stock. works well

Dave, Crash,

Thanks. What I'm wondering is what lead(s) did you run from the FP to the FP connection on the MS Relay board?

Did you disable or jumper the FP relay on the factory relay board in any way?

TIA,

On mine, I left the wiring stock from the relay board to the fuel pump.

On the megasquirt relay board, no connection to any of the terminals for the fuel pump.

Now, I did have the ecu plugged in to the harness...I am not sure where the fuel pump gets its 3 second delay.

crash - which ECU are you refering to? Stock or MS?

Stock ECU left in place. all sensor inputs went to the megasquirt. All I did was remove the sensor wires from the devices, then attach the megasquirt wires to the devices.

I did not touch the stock relay board.

I really used the megasquirt relay board as a big terminal strip...

Dave,

How do you have your MS realy board wired for the Fuel pump?

Crash,

So you're relying on the stock ECU rather than the MS-ECU for the Fuel pump control.

I've pulled the stock ECU out completely and am relying on the MS relay board and ECU only.

I guess I'lll have to go through the schematics again for both relay boards and see if the redundent relays aren't creating an open circuit some how.

Thanks again,

Gerard

It just comes off the pin on the terminal strip. I don't remember the number. I hooked up the + and ground backwards at the pump one time and it didn't run. It's hard to see so that is easy to do. If that doesn't work check continuity on the relay board for the pump circuit. Check the relay by swapping it with the others. I that stuff but sometimes you have to do it.

Dave

OK Dave,

I see what you're describing. You rewired the FP directly for the MS relay board. That makes sense.

Where I'm running into trouble (I think) is that I'm only taking the ground side of the FP connection (#19 wire from stock relay board) and running that to the MS relay board. THey're both ground so that parts fine.

What's messing me up is that the #19 wire on the stock board comes after the FP relay, then goes to the other relay on the MS board.

I'm now going to get the FP ground side from in front of the stock relay (bypassing it) and run it to the MS relay. Then all should be fine.

Thanks for letting me think out loud.