In Need of Some Help 1996 Z71 Stalling Issue
March 29th, 2011, 6:30 AM
#1
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In Need of Some Help 1996 Z71 Stalling Issue
I have been battling an issue with my truck for about a month now and decided it is time to take it to the boards for some much needed help as it has me very confused now.
About a month ago I was getting ready to leave from work and my truck died in the parking lot. I quickly figured out that the fuel pump was not running. I was pretty frustrated at the time because the pump in the truck was only about 15,000 miles old, and the sending unit was replaced about 1 1/2 years ago because I had to replace the tank so I replaced that at the same time.
Popped the hood and was checking things while trying to get it started, I don't think the problem is coming from there. Every time the key comes on the pump relay pulls in for a few seconds as it should and it always seems to come on at the right times (when its cranking/running/when key comes on to prime). Decided to run 12V (direct from the battery) to the plug at the tank and try that. When I did at first the pump did not run. Out of frustration I gave the tank a whack and the pump started, and the truck ran. Plugged the pump back in normal and it still ran. Immediately assumed it was the pump was shot. Dropped the tank put in a new pump. Truck ran fine for two days same problem came back.
Next put in a pump relay, truck started once or twice didn't go anywhere, problem still there. Unhooked plug from at the main harness and sending unit by the tank, sprayed in some PB Blaster on both ends of the plug, tightened up the pins in the plug some, put on some contact grease and the truck ran fine for a week and a half. Then same problem came back. Cut off the ground connector stripped back new wire, put on a new ring connector, drilled a new hole in the frame, cleaned up the frame there with the grinder, used a new bolt put contact grease on all of it. Truck ran for 2 days and the same thing happened again.
I laid under the truck with it running, wiggling and pulling on all the wires/connections and the pump never even sputtered. It will start run and it may run for 5 minutes may run for an hour. In the last two days I drove it for 45 miles with no issue. This morning I started it and it was running for 5 minutes to warm up in the driveway and it died. Turned the key and it started back up like nothing was wrong.
Oh and the whole time the check engine light never comes on (except for the normal) or throws any sort of code.
At this point I am so confused I have no idea. Maybe now the problem is somewhere else, I have no idea none of it makes sense.
Any Suggestions?
About a month ago I was getting ready to leave from work and my truck died in the parking lot. I quickly figured out that the fuel pump was not running. I was pretty frustrated at the time because the pump in the truck was only about 15,000 miles old, and the sending unit was replaced about 1 1/2 years ago because I had to replace the tank so I replaced that at the same time.
Popped the hood and was checking things while trying to get it started, I don't think the problem is coming from there. Every time the key comes on the pump relay pulls in for a few seconds as it should and it always seems to come on at the right times (when its cranking/running/when key comes on to prime). Decided to run 12V (direct from the battery) to the plug at the tank and try that. When I did at first the pump did not run. Out of frustration I gave the tank a whack and the pump started, and the truck ran. Plugged the pump back in normal and it still ran. Immediately assumed it was the pump was shot. Dropped the tank put in a new pump. Truck ran fine for two days same problem came back.
Next put in a pump relay, truck started once or twice didn't go anywhere, problem still there. Unhooked plug from at the main harness and sending unit by the tank, sprayed in some PB Blaster on both ends of the plug, tightened up the pins in the plug some, put on some contact grease and the truck ran fine for a week and a half. Then same problem came back. Cut off the ground connector stripped back new wire, put on a new ring connector, drilled a new hole in the frame, cleaned up the frame there with the grinder, used a new bolt put contact grease on all of it. Truck ran for 2 days and the same thing happened again.
I laid under the truck with it running, wiggling and pulling on all the wires/connections and the pump never even sputtered. It will start run and it may run for 5 minutes may run for an hour. In the last two days I drove it for 45 miles with no issue. This morning I started it and it was running for 5 minutes to warm up in the driveway and it died. Turned the key and it started back up like nothing was wrong.
Oh and the whole time the check engine light never comes on (except for the normal) or throws any sort of code.
At this point I am so confused I have no idea. Maybe now the problem is somewhere else, I have no idea none of it makes sense.
Any Suggestions?
March 29th, 2011, 11:43 AM
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The pump I replaced 15,000 miles ago was the original which I replaced with another direct from GM pump. When I dropped the tank the other day I replaced it with an aftermarket one.
March 29th, 2011, 12:00 PM
#4
Okay, one thing you can do is to measure the voltage at the 20A ECM-B Mini fuse against a known chassis ground under the hood. Compare that against the voltage across the positive and ground terminals at the fuel pump. There could be a significant difference due to the loss over the wiring.
March 29th, 2011, 1:07 PM
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You more than likely have a bad tank sending unit that is burnt out where the fuel pump connector attaches to the top of the sending unit. I replaced 3 pumps and on the 4th time I noticed this area had literally burned out. I don't see how it kept from catching on fore other than lack of oxygen to it. I replaced the whole unit with new pump included and have had no trouble since...
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March 30th, 2011, 7:40 AM
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I seem to have the same problem with a 6.5l Diesel. Thought it might be the Electronic accellerator as the engine does not run out of fuel just stops like yours...Humm
April 2nd, 2011, 12:41 PM
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Well I pulled the tank down Tuesday night, pulled out the sending unit and found nothing wrong. No burnt wires/connectors, nothing loose, nothing wrong. Tightened up all the connectors to insure a good connection and reinstalled. Took a resistance meter and checked the wires on the sending unit no issues. Have drove the truck for 150 miles since then. No issues.
Keeping my fingers crossed.