changed thermostat, m50nv won't start now

[ScHpAnKy]

I was fixing some drivability issues (throttle cable, dipstick o-ring, thermostat housing/thermostat) and after bleeding the coolant system once and adjusting the throttle body set screw and throttle cable the car just shot the idle way up and when the coolant started to sputter out from the bleed screw I shut it off because the gauge was started to get too close to the danger zone.

I tried starting it when the block and coolant were cooled down, and there's no "buzzing" / priming sounds when the key was in the on but not crank position, now I don't get anything except an engine that cranks and cranks.

Plugs are brand new, injectors are newish, coilpacks are newish and in good shape, I'm getting voltage at the in-tank fuel pump and just to be safe I swapped the fuel pump with the good one in my iX and the iX started just fine.

Unfortunately, this also happened at night time so I didn't get a chance to OHM out the CPS, but I'm thinking that the CPS died when some of the coolant leaked on it when I was changing the thermostat. Possibility?

I'm literally finished with the car now except for one more coolant bleed, so it's frustrating that it just doesn't want to start now.

[eurosport22]

sounds right to me. except i think usually it takes the cps working to run the fuel pump relay. mine will turn the pump on with the key every now and then

[ScHpAnKy]

sounds right to me. except i think usually it takes the cps working to run the fuel pump relay. mine will turn the pump on with the key every now and then

so you're saying the fuel pump relay will only work with a working CPS, that leads me to believe it's definitely the CPS, then... I tried swapping the fuel pump relay too when I noticed it wasn't priming anymore, so it makes sense that it's dead

[7pilot]

I don't believe you'll have the pump prime circuit on an 88 up 325, ie, the single pump cars.
The twin pump cars have the priming circuit, and this includes the M3.
Coolant spilt on the CPS won't hurt it but make sure that the CPS bracket has not been bent, plus ensure that the CPS is within the recommended distance to the trigger wheel.
If you jump T30 and T87 on the fuel pump relay, it would rule out a bad relay and bad pump wiring if the pump runs in the swap chassis.
Revise the work that you did during the T'stat replacement in case you left a MAF unhooked.

m

[ScHpAnKy]

I'll have to lookup the distance, but replacing the CPS got my car to fire right back up again - so happy to have one problem knocked out.

[trackjunkie21]

Check the injector harness ground which connects to the aluminum bracket on top of the T-stat.