Hello everyone! It’s been a while since I’ve posted here. I used this forum a great deal when I first purchased my car in 2008. Those were fun times. My H3 base model and I have have a lot of good times together and at 140k she still a cool ride. For some reason the forum didn’t recognize my sign in so I’ve had to sign in with a different email address. I’m hoping the brain power here on the forum can help me further diagnose a fuel delivery issue. Sorry for the long post but there was a lot of troubleshooting going on.

I got in my hummer a few days ago and tried to start it, it would crank but not start. I thought it might be the pass lock system as I triggered it one time in the past and had to wait 10 minutes for it to restart. What I didn’t know was that the pass lock indicator light on the dash should be blinking when it’s in that triggered mode so I never looked for it. After several attempts and waiting the 10 min, it still didn’t start. I disconnected the battery to see if it would do a reboot of some sort. But no luck. Still assuming it was the pass lock system I purchased a new ignition switch with pass lock sensor. I removed the sensor from the new ignition switch and replaced the old one and still didn’t have any luck. I went through the re-programming sequence many times perhaps 10 or 12 and no luck. But it was then that I noticed that the pass lock indicator light on the dash never blinked, it was always on solid and would go off after a few seconds with key on. So now I am suspecting the fuel pump is bad. I found there was no fuel pressure at the fuel rail so I checked both the relay and the fuse for the fuel pump circuits. Both were fine. Suspecting the fuel pump, but not being absolutely certain and having a full tank of gas that I did not want to siphon out, I used a holesaw and cut a hole in the floor to access the top of the fuel pump for circuit testing. That’s when things got interesting. I disconnected the fuel pump power connector and tested it for voltage. (Gray wire positive, black wire negative) With the connector disconnected I got 12 V for a few seconds with the ignition on and then also when I cranked the engine. However, when I plugged the connector back in I got 0 volts at initial key on and 0 volts when cranking the engine. Maybe this is due to the load of the fuel pump? At any rate I connected a separate 12 V power to the probes I had in the connector with the connector attached to the fuel pump and the fuel pump ran and the car started. So the fuel pump appears to be good. So I get power to the connector when it’s disconnected but not when it’s connected to the fuel pump. It’s seems when a load is registered on the power circuit to the fuel pump, something shuts it off. PCM? Pass lock? Something else? I feel like I’m close to figuring it out but need some more experienced brains on it. With all the work I just put in to it I’d hate to have to take it to the dealership at this point. Failure is not an option. I should also mention I went ahead and installed the entire new ignition switch with the new pass lock sensor. I look forward to to the advice that you might have to help me figure this out....thanks in advance!