Mechanics

FUEL GAUGE STAYING PAST FULL AND SUCKING ENOUGH JUICE TO MAKE TRUCK STALL.

1997 Chevrolet Blazer • 133,595 miles

I had and erratic fuel gauge needle and truck was sluggish. Suddenly the needle went past full and stucked there. Later I got a check engine and truck stalled. After further tests the P0107 MAP low voltage code came out but the problem was not the manifold absolute pressure sensor. There is a 5 wires connector sticked to the driver fender that I unplugged and the engine started fine and ran fine. After further test the EGR and MAP voltage went back to 5 volts instead of 2.08v before I unplugged that connector also the fuel gauge went back to empty position. No more engine code, engine starts fine and run better but as soon as I plug it back the engine stall or perform sluggish and needle go back past the full position. The five wires are black, green, pink, white and grey. The grey give the 5 volts and the pink the 12 volts. Strange thing is that both side of the connector the grey wire give the 5 volts when grunded to the battery. I'm joining an image so you can help me identify this connector and what's for exactly. Thank you !


Avatar
Takwakin
December 31, 2011.



Also you can see a free round connector in the picture. It's a big red wire and I don't know what it is used for because it was there when I bought the truck. Maybe the starter wire they changed and left the older there. Not sure.


Tiny
Takwakin
Dec 31, 2011.
Shorted fuel gauge, wiring, or sending unit.


Rivermikerat
Dec 31, 2011.
I would need the location of connectors so I can test it. I have the full wiring diagrams but don't show the exact location of the connectors.


Tiny
Takwakin
Dec 31, 2011.
Purple wire on instrument cluster connector, pin 29 to fuel level buffer module, pin L, under the cluster. The schematic I have doesn't show any intermediate connectors. Instrument cluster, fuel level buffer module, engine control, and pump. Pump is in the top of the tank.


Rivermikerat
Jan 1, 2012.
Ok thank you I will give it a try but before I will get the diagram location because pin L, pin 29 and purple. It don't give me the exact location. For now with the connector underhood unplugged the truck run fine. Also do you know what is the exact usage of this connector?


Tiny
Takwakin
Jan 1, 2012.
I'm not sure about the connector. But, there is a set of wires that runs to the engine control module for the pump from the fuel level buffer module. I'm guessing this might be the wires/connector you disconnected.

Pin 29 is on the instrument cluster. The dash gauges. Where the speedometer and fuel gauge are.
Pin L is on the fuel level buffer module. It's behind the dash in the center.


Rivermikerat
Jan 1, 2012.
What is the usage of this fuel level buffer module? Nothing seems to change when its unplugged except the needle not showing the fuel level?


Tiny
Takwakin
Jan 1, 2012.
I'm not sure, because there's nothing definitive in my reference, but I would say voltage stabilization. I think that's why when you unplugged the wires from it to the engine control, things went back to normal.


Rivermikerat
Jan 1, 2012.
I printed the 4 pages for wirings of engine but from a Jimmy 1997 instead of a Blazer so the wires are not the same color. I have to find what is where prior to further testing.


Tiny
Takwakin
Jan 1, 2012.
Here.


Rivermikerat
Jan 1, 2012.
Page 1 of 3