DaleTx

I am having a problem with the connection between my wire harness (red and blue) connectors and my GM ECU. I have 12 plus volts going into the ECU but the output lead for the fuel pump measures only 9.8 volts. My fuel pump won't turn on with the low voltage, and the car won't start.

I suspect that I have a bad connection between the wire harness and the ECU. What can I do to improve the connection? The wire harness has been plugged in and unplugged several times and I think the connections are a bit loose now. The engine is a GM LS2 with a GM ECU.

I am looking for Ideas on how to restore a good connection between the wire harness (red and blue connectors) and the ECU. Thanks.

gofastwclass

iTrader: (2)

I'm going to take some leaps and assume a few things because you really haven't given much to go on, If you're like me (and many of us on here) you have more than one vehicle so I can't automatically assume it's the one in your signature...

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If I am correct about these things, your root problem is not 9V out from the PCM. The root problem is the PCM is designed to control a relay that controls the fuel pump. Since you are only getting 9V out, you may have damaged the PCM's fuel pump driver that controls the relay you don't have. The good news is 9V is still plenty to kick off a relay, but the PCM may not live as long as it could / should had it been protected by a fuse and relay it's entire life.

Of course this is all a wild guess because of the previously mentioned assumptions. If this doesn't solve your problem and it is a conversion or retrofit, you would get better response in the conversions and hybrids area.

DaleTx

Sorry for the lack of information… here is a bit more detail:

You are using this in a non-factory situation.
Correct… I have installed an LS2 into a Gen 1 Camaro.

You are using an aftermarket harness or modified factory harness.
Correct… I am using an aftermarket/custom wiring harness, GM PCM, and the engine is port fuel injected .

The engine (this combination) has never run in this vehicle.
No...the engine was built new, and fully tuned and tested on an engine dyno prior to installing in the car. The engine is set up with an OBDII port for tuning and diagnostics. The fuel system is set up with a Vaporworx digital control and a GM CTSV submerged fuel pump. The engine has been installed in the car and running perfectly with no issues for the past year. This week was the first time I have had any problems.

This vehicle was not previously fuel injected.
Correct… previously had a gen 1 small block.

You are running the fuel pump directly from the PCM.
No… the PCM supplies the 12V power supply as a switched trigger for the digital controller. The power supply for the fuel pump comes from a fused circuit connected to the battery.

Of course this is all a wild guess because of the previously mentioned assumptions. If this doesn't solve your problem and it is a conversion or retrofit, you would get better response in the conversions and hybrids area.

Really what I’m trying to do is troubleshoot my problem. I have tested the fuel system, alternator, and circuits supplying power to the PCM and everything checks out. My next step is to check the connection from the wire harness to the PCM (red and blue connectors). After that I will check for shorts or bad connections in the wiring harness. This started out as an intermittent problem (random engine shut down while driving). Right now the car won't start... and there are no codes showing. The voltage to the fuel pump trigger is only 9.8 V rather than 12V (not enough to turn the fuel pump on).

I do appreciate your input and if you have any ideas to help me troubleshoot the problem I would appreciate the help. Thanks