What triggers the Fuel pump to come on?
 

The rx has been sitting for months as I slowly work on it. With relocation and having to rebuild my buddies car and my fathers vette, I've had very little time to work on the rx. I've gone through the system did braided hose, parallel setup with a walbro pump. I wanted to flush the system out, undoing the connections at key points and letting the pump run. However, I found that won't click the pump on with the engine off and in the on position. I took the DVM and I'm getting 12v from the white/red wire (88 T2), but is way to thin of gauge to be the power wire..let alone it doesn't connect to the fuel pumps terminal in that harness.

The only thing I can think is that the computer won't click it on because the CAS is unplugged along with a bunch of the other sensors that are come out of the drivers side harness.

So basically, what are the condtions that need to be met for the fuel pump to run.

Im pretty sure the mass air flow senser clicks the pump on, but there is a little yellow connector on the engine wiring harness that you can put a jumper wire on and it will turn the pump on when the ignition is on, the main reason for it is to check for leaks after you have worked on a part of the fuel system.

What he said. To test the pump you'll need to jumper the yellow check connector. Don't leave the jumper wire in though.

ahhh. I just powered the pump directly with a jumper wire from my charge terminals behind the license plate.

But it's normal for the pump not to turn on with the ignition on? Hence needing the jumper wire up front? I'm just wondering if it's going to fire once I put it all back together :D

Yeah its not suppost to come on till the motor starts cranking

Turn the key to start. That should kick the pump on, and then it'll run with the key in the on position without a jumper.

Thanks guys. I thought I'd some how screwed up some wiring..even though no wiring had changed. That's a load off.