LS2 Fuel Pump Wire Not Energizing?

[1967ls2]

I purchased a harness from Current Performance few years back. I have a 2005 LS2 from a GTO.

I'm having a problem with the fuel pump signal wire not energizing. I believe the problem is either with the fuel pump relay at the fuse box or at the ecu connection. I was hoping to get some help diagnosing.

The fuel pump relay at the fuse box has a red power wire that is hot under cranking and when the key is in the accessory position. There is a black wire that appears to be constant ground. There are two other wires, green/white and a gray wire. Neither have power under cranking or accessory position.

I was hoping for some operational understanding. I believe the green/white wire goes to the ecu which is signal (blue ecu connector #45)? And the gray wire is the fuel pump wire that brings power to the pump?



If the gray nor green/white wire ever receive power I'm thinking the ecu is either not sending signal through the green/white wire to the relay or the relay is bad? I tried swapping the relay with the identical ignition power relay but nothing changes.

Any help would be greatly appreciated.

[1967ls2]

So I jumped the red wire to the green wire and the fuel pump kicked on. I did the same to the gray wire and the fuel pump kicked on.

So now I need to figure out why the power is not being sent through the green wire from the ecm when the accessory power is keyed?

[csouth]

I have a wiring diagram from Current Performance that might help. Send me your email address....

[1967ls2]

Thank you for the response pm sent with my email address.

[csouth]

Sent diagram. You need to find the wire in the CP harness that is for key on/run, its pink in mine. That should wire to what would be your coil wire I belive if you still have the factory harness. I my CP harness its pink/black.

[1967ls2]

I don't think that's the issue. When I hit the key everything turns over as it sounds like it wants to start. I think there is an issue with that green/white wire?

Or are you saying there could be a problem with the pink ignition wire?

[csouth]

I don't think that's the issue. When I hit the key everything turns over as it sounds like it wants to start. I think there is an issue with that green/white wire?

Or are you saying there could be a problem with the pink ignition wire?

So in my setup, I have a pink wire(body harness) connected to a pink/black wire in the CP harness. The pink/black wire in my CP harness is for 12v switched power. Do you have a test light? If you don't have a pink\black wire in your CP harness, you have to find the wire that is 12v switched. I'm assuming the red wire is connected to the hot side of your starter?

[1967ls2]

So my ls2 has been wired for years in my 67 Camaro. I recently moved the pcm under the dash and relocated the coils. I never moved or unconnected the five wire hookup that has been spliced into the car but I guess I could have unintentionally bumped the 12v wire or maybe blew the ignition fuse. I have a test light and will check to confirm the 12v wire is hot when the key is on. I think I assumed the pcm was getting power because the red power wire at the fuse box was hot but I guess it actually receives power through the alternator which is tied directly into the battery.

Hopefully it's just a blown fuse and I don't have to chase the ignition wire down.

Thank you for the help and suggestions.

[1967ls2]

I just confirmed the ignition wire had power at the splice into the harness and all the way to the ignition relay at the current performance fuse box. Scratches head? I assume I could just make a jumper wire from the pink 12v ignition wire at the fuse box to the green/white wire next to it in the fuse box so they both trigger at the sane time and trigger the relays and that should kick on both the pcm ignition and the fuel pump.

But the bigger question is why am I getting no output from the pcm to the signal wire for the fuel pump relay?

[1967ls2]

I just powered the fuel pump by running power directly to the pin on the connector. I guess that tells me the harness, connector and relay are good.

Does the pcm have to be grounded separately? I thought the pcm and harness were grounded from the harness on the back side of the driver's side head. If that's not it, then the pcm is malfunctioning?

[1967ls2]

I tried to ground the pcm but that didn't change anything. I also ran a jumper wire from the ignition 12v wire to the green/white wire assuming having the pump on then the engine would start but it didn't.

Now I'm really stumped. Not sure what else there is to try.

[csouth]

No, you are correct the PCM is grounded via the wire on the head. I'm assuming your motor is also grounded? So the pump does not prime at all when you put the key to the "on" position?

[1967ls2]

I have a ground from the battery directly to the frame and a ground from there to the engine. I also have a ground from the battery directly to the body.

When the engine is in the run or in accessory position the fuel pump does nothing.

I'm so confused here. The engine has been in the car for years running perfectly. I've had the current performance harness for at least 3 years without issue. I decided to relocate the pcm from the fender to under the dash and relocated the coils off the valve covers. The only modification to the harness was extending the plug that plugs into the coil harness by about a foot and a half on both sides. I soldered all the conections and used heat shrink to wrap them. Other than that nothing has changed. I'm perplexed. What would cause the fuel pump wire not to energize? And when I jumped power directly to the fuel pump wire the pump starts priming and I assumed the engine would then fire up, but it just cranked.

[1967ls2]

Ok, I think I'm ready to call off the search party. I went back and double checked all the fuses in the current performance fuse box and wouldn't you know it I must have missed one because I found a blown pcm ignition fuse. I didn't have a spare so I swapped the trans fuse and bumped the engine and heard the fuel pump starts priming. I couldn't fire it up because the babies sleeping but I'll give it a go tomorrow to confirm it runs. I feel like an idiot for not seeing it the first time. I looked them over but I guess not close enough.

[csouth]

Glad you got to the bottom of it.

[1967ls2]

Now I just have to figure out why it sounds and feels like it's only firing on 6 cylinders.

[csouth]

Now I just have to figure out why it sounds and feels like it's only firing on 6 cylinders.

Is your MIL hooked up?

[1967ls2]

I purchased a Bluetooth OBD2 reader and pulled the codes. Turned out 2, 4, 6 & 8 were throwing codes. I went to pull the coil harness to confirm I didn't screw up splicing the connection to the harness where I extended it to reach the relocation spot where I mounted the coils. I noticed the coil harness was unplugged from the engine harness. I must have forgotten to connect it after I bolted the coil mount to the engine. They are mounted down low and hard to reach. I didn't get a chance to fire it up because my 10 month old was sleeping but I'll confirm it fires up tomorrow and all is well. I'll let you know.

[1967ls2]

Yep, fired up. No trouble codes. Thanks for helping me find all my bonehead things I overlooked!

[csouth]

Yep, fired up. No trouble codes. Thanks for helping me find all my bonehead things I overlooked!

Glad you got it worked out....