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I put a 5.3 in my 71 Camaro along with a Tanks inc in tank fuel pump.
My AAW update harness came with a fuse provision marked "fuel"...so what I ended up doing was using a 40 amp bosche style relay to pull power from that fuse and energize the pump.
The relay is attached to the fuse panel with a factory looking holder so it's all one piece.
I wired the relay with the trigger wire from the PCM exactly like this
My problem is, twice now I have had issues with the car starting and it ends up being the fuel pump isn't coming on.
typically all I had to do was turn the key to run and I could hear the pump come on and the car would start. Not this time.
I tinkered with it the first time and couldn't really tell you what I did. I just swapped relays, unplugged things and so forth. And when I turned the key on the pump came on.
From what I can tell after putting a light on the relay is that all points have power, and there isn't a break in the wire going to the rear of the car. The only other thing I can think of is maybe a bad ground to the relay...but it's tied into the harness ground and that's secure.
I can put a 12v jumper to the harness plug under the dash from the fuse block and the pump energizes and the car starts.
I can't think of anything else unless the PCM fuel trigger is doing something sketchy.
The fuel pump wire in your harness is coming from your computer correct? If so, the computer has a setting for how long that wire stays hot when the ignition key is turned on. I think the default is 5 seconds. That may not be long enough to prime your fuel system and allow the motor to start when cold. You can add time to it through the tune.
You can also run the pump without using the fuel wire and just trigger off your ignition switch. If you do that make sure your ignition switch stays hot during cranking. My 1960 Chevy switch did not and I had to get a newer version from AAW.
On my car using a Rick's tank with a1000 pump and aeromotive regulator, I was having cold start issues even with the pump trigger separated from the computer (no time out on the pump) I ended up adding a check valve on my feed line and it solved my problem.
Thanks for the reply, my car is at the shop being buffed right now. I had to put a jumper wire on it from the fuse box to get it to start for those guys. I'm about 2 miles down the road from there so this should get me home.
But I am going to do a re-wire and make the trigger an ignition switched source. I am pretty sure the ignition switch is hot during cranking, but will def look into that
07-14-2015, 07:37 AM
Fuel Pump power issues 
