Fuel Pump Not Priming
03-02-2014, 10:43 PM
#1
Teching In
Thread Starter
iTrader: (2)
Join Date: Apr 2011
Posts: 33
Likes: 0
Received 0 Likes
on
0 Posts
Fuel Pump Not Priming I'm ready to drive the car and then this happens! I have a 97 Z28 with a Racetronix 255lph pump and the upgraded wiring harness. It sat for 6 years, but has been running and was recently dyno tuned and driven around the block. The last time I started the car a week or two ago I noticed the fuel pump wasn't priming and my pillar gauge was showing no pressure when I turned the ignition on. I tried it again a few minutes later and it seemed fine. Started and ran with full fuel pressure. I go to start it again today and no prime, no pressure. I have:
Turned the key off and on multiple times to see if I can get it to prime. No luck.
Cranked the car a little. No luck
Checked the PCM Batt fuse and the Racetronix wiring harness fuse and both are good.
Run 12v to Fuel pump prime connector. Heard click at back of car but no prime.
Run 12v to gray wire from the fuel pump relay on driver floorboard. Heard click but no prime.
Ran 12v to gray wire at the back of the car going to the pump. I got it to prime once for a second or two but I couldn't get it to prime again.
Visually the under car pump electrical connector and pump relay as well as visible wiring look fine.
Does anybody have any suggestions before I pull the tank and chase what I'm thinking is a loose connection on the pump? I need to pull the tank again anyway, but wasn't ready to do it just yet.
Turned the key off and on multiple times to see if I can get it to prime. No luck.
Cranked the car a little. No luck
Checked the PCM Batt fuse and the Racetronix wiring harness fuse and both are good.
Run 12v to Fuel pump prime connector. Heard click at back of car but no prime.
Run 12v to gray wire from the fuel pump relay on driver floorboard. Heard click but no prime.
Ran 12v to gray wire at the back of the car going to the pump. I got it to prime once for a second or two but I couldn't get it to prime again.
Visually the under car pump electrical connector and pump relay as well as visible wiring look fine.
Does anybody have any suggestions before I pull the tank and chase what I'm thinking is a loose connection on the pump? I need to pull the tank again anyway, but wasn't ready to do it just yet.
03-07-2014, 03:34 PM
#2
Teching In
Thread Starter
iTrader: (2)
Join Date: Apr 2011
Posts: 33
Likes: 0
Received 0 Likes
on
0 Posts
Just in case anyone looks for an answer to this later on, it was not a common issue and luckily did not have to pull the pump. Turns out the 300amp Moroso master cutoff switch is only rated at 300A on the battery posts. The alternator posts are only good for 20 amps, so I was using a 210 amp alternator to send 20 charging amps to my battery and fuel pump (also explains why the car was eating batteries for breakfast). I had my pump wiring harness to the downstream side of the switch, so I guess eventually the 20A circuit went bad. Moved it to the battery side of the switch and primed right up.
Talked to Moroso, and they offer a 250A relay that negates the need for the 20A circuit in the switch and still shuts off the alternator current when the cutoff is turned off. It's on the way and should be here mid next week.
Talked to Moroso, and they offer a 250A relay that negates the need for the 20A circuit in the switch and still shuts off the alternator current when the cutoff is turned off. It's on the way and should be here mid next week.
03-07-2014, 10:50 PM
#4
Teching In
Thread Starter
iTrader: (2)
Join Date: Apr 2011
Posts: 33
Likes: 0
Received 0 Likes
on
0 Posts
They do when they want to reroute and wrap some wiring and do a couple of other things while the tank is out. It's an aftermarket tank and the edges are razor sharp. I think I protected the lines and wires well, but I'd like to do my paranoia check on them. Plus, I have two amps and a nitrous bottle/heater on a rack on the deck that would have to be disconnected and removed to cut the access panel.
