HELP! Quick fuel pump wiring question

[exboatracer]

My fp relay wire is connected to the grey wire that comes from the c-100 firewall connector and it powers right up. Also my oil pressure sender is not installed yet and the engine runs. I also thought the tan wire from the oil sender needed to be hooked up to the fp wire so thats a puzzle to me too. Like gagliano7 said, maybe theres a different way to connect them. This is on a 1990 truck,5.3 4l60e swap with a NP harness. Try checking your grounds.

[lost06]

Ok. Heres what I have so far....

Terminal 86 on the relay should be a constant ground. But with the volt meter, it shows to be putting out around 12v. I am attaching a generic diagram I made. I was thinking that maybe i should ground the relay directly???

[exboatracer]

I forgot to tell you an important part of my initial start-up. My first attempt to power up the fuel system (to check for leaks) failed.I turned the key and nada. Went looking and found a blk/wht wire coming from c-100 and according to my wiring diagram it was a ground. Hooked it to the firewall and the f/p powered right up. I'm not good with wiring but I hope this helps or someone else can chime in.

[lost06]

Thanks. Ill look when I get home. However, I cut the wire and grounded the end going to the relay and it primed but quit cranking. So I reconnected the wires and it would crank again but no fuel pump.

[capricefrk013]

Untitled5.jpgGoing through the oil sender is probably a safety feature to shut the fuel pump off in case of a roll over. Pin 87A on the relay "should" be connected to the oil sender. This could be incorrect and maybe some will chime in to confirm that.

I forgot to tell you an important part of my initial start-up. My first attempt to power up the fuel system (to check for leaks) failed.I turned the key and nada. Went looking and found a blk/wht wire coming from c-100 and according to my wiring diagram it was a ground. Hooked it to the firewall and the f/p powered right up. I'm not good with wiring but I hope this helps or someone else can chime in.

That Black white is a ground feed fed by the ECU to trigger the relay to turn the pump on.

Thanks. Ill look when I get home. However, I cut the wire and grounded the end going to the relay and it primed but quit cranking. So I reconnected the wires and it would crank again but no fuel pump.

I Need to know what wire does what to better help you figure this out but maybe this pic can help you figure out what goes where.

[lost06]

Please see my post here. http://www.ls1truck.com/forums/lsx-t...ease-help.html

it might be a little more descriptive.

Thanks for the help and advice

[exboatracer]

Thanks caprice for that oil sender rollover info. When I removed the old 350 I marked that tan wire that came from the oil sender since it was tied into the f/p wire. (I had no idea why oil sender and f/p relay could be related). Now I'll tie it back in.