Recently switched from an MS3x ECU to a new MS3Pro PNP for my 1996 Miata and have an issue with the fuel pump running when the key is off.

Previously, I installed the Trackspeed fuel pump relay/rewire kit which I think is why it's doing this. It was fine with the MS3x, but I'm guessing when the PNP is turned off it puts the fuel pump to ground which is why the pump still runs when the key is off. With the Trackspeed rewire kit you are supposed to bypass the fuel pump relay under the dash and modify the wiring at the pump. So I'm guessing this combination of things is why my pump runs with the key off. Fuel pump primes for 2 seconds with the key on and then turns off as it should.

Currently, I have a little switch to disconnect the wiring so I can turn the pump off manually, but it's not a good solution and I'm probably going to forget and kill my battery one of these days.

Wondering if anyone else experienced this and what your fix was. I reconnected the fuel pump relay wiring under the dash but then the pump didn't come on at all so I put it back to the Trackspeed directions. Hoping there is an easy fix and I don't have to add another relay.

 

I don't think that's correct. Maybe it was a workaround for the MS3x. But nowadays, you keep the OEM Fuel Pump Relay intact. Instead of it providing power to the pump, you use it to engage the new relay.
FM keeps a copy of the instructions.

 

Thanks for the link. After looking closer at the pictures on Flyin' Miata the relay is definitely wired differently to the one I have. I got mine in 2019 from Trackspeed.

 

Got it solved. Anyone else who runs into this issue here is the fix.

I compared the new version Flyin' Miata fuel pump rewire kit to my Trackspeed version and was able to rewire it.

First, reconnect the OEM fuel pump relay under the dash to OEM configuration.

Cut the small gauge red wire loop on the Trackspeed relay, connect the small red wire end to the Blue/Red OEM wire.

Cut the blue wire that was connected to the Blue/Red OEM wire, and connect it to ground.

Now everything works with the key and doesn't run when the key is off!