Help diagnosing fuel pump

TonkaChuck

New Member
Joined
Oct 30, 2018
Messages
3
Location
Maryland
First post!
I have an 00 Wrangler TJ Auto 6cl. One day the Jeep cut off on me and I couldn’t hear the fuel pump humm on the priming cycle. I had the pump replaced, but still no start. I almost got to the point where I was going to replace the PCM, but I decided to hook the pump directly to the battery and try to start the Jeep. Started right up and was able to run. I checked the relay and I can hear it click on prime cycle. I bridged the relay and I’m getting 12 v across but no fuel pump running. Does anyone have ideas?

No check engine light. Replaced CKS In the troubleshooting process.
 
I suspect that something is triggering the ASD relay which cuts power to the fuel pump. Something else is going on.

What have you done to the Jeep? Loose connections to a sensor can cause this.
 
Do you get voltage at the connector at fuel tank? Good ground?

I dont get voltage at the connecter, but ground works. The ground is actually bypassed around the connecter. So when I ran the hot wire from the battery, it works. I'm thinking i may have a broken wire somewhere between the relay and the connecter?
 
I suspect that something is triggering the ASD relay which cuts power to the fuel pump. Something else is going on.

What have you done to the Jeep? Loose connections to a sensor can cause this.
I would agree, but my understanding is there is nothing between the relay and the pump that would cut off the voltage. I get 12V at the relay, but when bridged, there is 12V across the relay but nothing at the pump.

I've replaced the CKS and the pump and that's the extent of my replacment.

I actually was forced to move my jeep today so they could pave my parking lot and I was able to drive it by running a wire from the Relay input (so that the wire was post-fuse) to the Positive line on the pump with a desklamp switch halfway on the line. Flip the switch, pump starts up, started the jeep immediatly after and the thing ran like a charm. No code pops or anything; just the fuel level sensor reading empty.