Hello everyone! It’s been a while since I’ve been on 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. 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. I didn't think to check for any codes prior to the battery disconnect so I don't know if there were any. Still assuming it was the pass lock system, and after reading posts regarding similar issues, 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 hole saw 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? Also, now that the car has started and run for a bit I checked for codes and found "fuel pump primary circuit" but I can't be sure that the code is from my introducing separate power to the fuel pump. I feel like I’m close to figuring things 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. I should also mention I went ahead and installed the entire new ignition switch cylinder 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!

 

I approved your thread that was moderated by somebody else. Don't know why the moderation except when you ask a question, ask it ONE TIME then WAIT for answers. Yeah you wrote a book but left out the important info..........

How long did the H3 sit before you tried to start it and discovered this problem?

Are you still using the Crappy Azzed Battery Terminal Connectors?

Did you clean the fuel pump connections with CRC Electronic Cleaner?

Is there any OBDII codes stored? If you do not know, scan it and report.

 

Hi Doc Olds, thanks for the reply! I did wait 24 hrs before I posted a second time. Does it normally take that long to post? I thought maybe something went wrong because my first post never posted. My second post came up right away. Here is the info you requested:

How long did the H3 sit before you tried to start it and discovered this problem?
OVERNIGHT

Are you still using the Crappy Azzed Battery Terminal Connectors?
YES, THEY ARE IN GOOD SHAPE AND CLEAN

Did you clean the fuel pump connections with CRC Electronic Cleaner?
NO, BUT AS YOU CAN SEE FROM MY TESTING PROCEDURE IT SEEMS TO RULE OUT CONNECTION ISSUES. I WILL GO CLEAN THE TERMINALS NOW AND REPORT BACK.

Is there any OBDII codes stored? If you do not know, scan it and report.
I DID NOT THINK TO LOOK FOR CODES INITIALLY AND I DISCONNECTED THE BATTERY. DOES THIS ERASE STORED CODES? IF NOT THEN, NO CODES WERE STORED INITIALLY. I RE-READ THE CODES AFTER APPLICATION OF SEPARATE POWER TO THE FUEL PUMP AND STARTING THE CAR. IT READ "FUEL PUMP PRIMARY CIRCUIT". AGAIN, I DO NOT KNOW IF THIS COULD HAVE BEEN CAUSED BY THE APPLICATION OF THE SEPARATE POWER.

 

Doc, I cleaned the terminals and connector for the pump...no change.

 

I do not care how many times you clean the OEM Battery Terminal connectors, they are complete 100% GARBAGE. Known issue in all H3/H3Ts and should be the first mod done to every one of them. Replace them with a quality aftermarket set like Stingers or your favorite brand. Do a search here regarding battery terminal connectors here to see the 100s of time this has been discussed. That is a side issue, but still potentially related.

You PCM stores the last 300 ignition cycles power or no power.

You may have a toasted fuel pump. Think of like a seized starter due to worn brushes, you can put 12V to it, but it does nothing.

 

Swap relay #66 with #72. Check/replace fuse #25.

 

Thanks, Doc Olds. I see what you mean about how crappy they are and I have been keeping an eye on them as potential trouble makers but they're not the issue in this case.

So if the codes were not erased when I disconnected the battery then there were no initial codes when the no start condition first happened. To be clear the engine is turning over, the fuel pump isn't getting power.

The fuel pump isn't toasted, it runs perfectly fine when I put a separate 12v source to it. The vehicle will start and run with the separate power to the fuel pump.

 

Thanks, Hummerz, I already did the relay swap. In fact I even tried putting in a jumper to bypass the relay with no change. I checked fuse #25 and it is ok...along with fuse #3.

I'm getting power to the connector for the wires to the fuel pump when it is disconnected, but the power goes to zero when I plug the connector back onto the fuel pump.

 

Go back to the fuse and measure the voltage with the pump connected then go to the relay and check. If good, send a jumper from relay 66 pin 87 to the fuel pump gray wire to check.