fuel pump question

What should the voltage read from the connector that runs the fuel pump? Its for a comanche, but I assume the cherokee is the same. And is there any fuse that the pump runs on or not?

Thanks

well if it's like my 89 XJ..... I have just under 11v with the few seconds of prime, then on crank I have just about the same. Running I do not know as the one I am getting the readings off of has a bad ("brand new" grrrrrrrrr) fuel pump that I will be changing again of Friday.

creekscout said:

What should the voltage read from the connector that runs the fuel pump? Its for a comanche, but I assume the cherokee is the same. And is there any fuse that the pump runs on or not?

Thanks

Click to expand...

Tough question.

On my 90 the power to the fuel pump is provided in three different manners:

While starting, the power goes from the starter relay, the fuel pump relay and ballast resistor are bypassed, and 12v is provided.

When running at WOT the fuel pump relay and ballast resistor are again bypassed, and power is provided through the oxygen heater relay, and 12v is provided.

Normal operation the power is provided by through the fuel pump relay and then through the ballast resistor. I believe that range starts at about 5v, and I don't remember the upper limit of the ballast resistor, assuming it is working correctly.

And though not asked, the ground for the fuel pump relay is through the ECU.