Installing TBI in my 89 Jeep Grand Wagoneer and have a question. Have everything hooked up, but have no fuel pump. I have injector pulse, and spark, and can make it run if I jumper the fuel pump, but ECM is not turning on the relay. Acording to my information, the controller sends a 12V signal to the relay to actuate it, which I am not getting. Checked at the relay and controller. Nothing!
So I guess my question is what does the controller need to see to send the 12V to the relay.

Thanks in advance, Andy

 

The power out, is only for ~2 secs., when you first go key on, then the power for the pump comes from the oil pressure switch.

Yes, it sends 12v to the relay winding, and the other side of the relay winding is grounded. If you have power *out* of the ecm to the relay, and no pump then it would seem there's a broken wire, a bad relay, or no ground for the relay.

 

Thanks for the reply. I do not get the 2 sec prime. Checked it at the ECM.

 

The output transistor for the FP relay commonly pops. Can be replaced with a 2N2907 (a little metal can xistr). I've done a number of them. Sometimes the PCB trace goes with it. Which is also easily repaired.

RBob.