Ok guys so went over to my cousins the other day to help him get his 03 350z performance running. Basically he blew it up last year so we picked up an 05 longblock for it and I helped him swap everything over and drop it in. So we got it all wired up and tried starting it but it just cranks and cranks. Figured it was a fuel problem so pulled the feed line off and sure enough no fuel came out. So we turned the key and didn't hear the fuel pump priming.

So next we pulled the fuse - looked good, and the relay was also fine, we even tested it with power to hear it click. So we decided to pull the pump out and hardwire it to the battery to see if it was junk or not. To our surprise, the pump worked fine when hooked to the 12v source. So next I figured it was something in the harness going to the pump. Hot wired the socket that the power goes through to get to the fuel pump harness and the fuel pump turned on so it wasn't that either. Tested all the sockets on the fuel relay spot on the ipdm and they all checked out good, but I then discovered that there was no negative on the relay sockets, so the ECU isn't commanding the pump on

There is no security light on, so its not the immobilizer ****ing up. Can anyone point me in the right direction? Is there a ground that could be disturbed or another relay or what? Im stumped. If it helps, the car is sitting on jackstands and the 02s and stuff arent plugged in but I figured none of that would play a role.

Also when the motor started let go before he though his battery died and he put in a new one (yeah, I know) but he was in a rush and put the terminals backwards, melted the negative ground cable a bit. But none of the inline fuses on the positive terminal popped so does the ecu maybe have internal fuses or something that could have popped? Is it time for a new ecm?

Any help, diagrams etc would be appreciated. Tried following schematics in the fsm but im no electrical engineer lol thanks guys.

 

Hooking the battery up backwards is never good... probably fried a bunch of stuff like the ECM.

 

Agreed- reversing the polarity on the battery terminals will often damage the ECM beyond repair. But without a CONSULT II, I'm not sure how you'd check it.

 

will a consult II be able to tell us if the ecm is fried? And also, if the battery was hooked up backwards wouldn't it have popped the inline fuses that are in the box on the positive cable? or no?

 

Anyone?

 

CONSULT II has the ability to determine if a ECM is functional. As for the fuse box, I'm not sure if it will protect from a sudden voltage surge. Glad to say, I've never tested it!

In any case, taking it to the dealer is likely the best solution at this point. let us know what they (or you) find.