Fuel Gauge Not Working Properly

jdaniel83 · August 26, 2011

I've searched the site and only found a few threads about this problem, but none of them really addressed the issue I'm having. My '01 2500HD Duramax's fuel gauge has been acting strange and for the most part doesn't work at all. Most of the time my gauge reads empty and the "Low Fuel" light stays on. The last two times that I have been putting diesel in it the gauge starts working and shows the tank filling up as I'm putting the fuel in, but as soon as I start it up and start driving it drops back down to Empty. Occasionally it will jump up to Full while driving down the road but most of the time it just sits on Empty. A friend of mine suggested getting someone to replace the "stepper motor" (or something like that) in the instrument cluster for the fuel gauge and another said it sounds like my sending unit is bad. Which sounds more like the correct diagnosis and is there a way to tell which it is? Thanks.

txab · August 26, 2011

Sounds more like the sending unit.

ChevyTech77 · August 26, 2011

Sending unit.

jdaniel83 · August 27, 2011

Damn that's what I was thinking and have been fearing. Guess I'll live with the trip odometer method for at least another week since I have to work this weekend but I hope to get to changing it out next weekend. Any tips or advice on changing out the sending unit?

Shaners · August 27, 2011

I believe you have to pull the bed or drop the tank. If you have very many miles on it and have never changed the fuel pump then you may want to consider it as preventive maintenance. Maybe the sending unit is part of the pump... I don't really know.

born-to-fish- · August 31, 2011

My '05 Sierra does exactly the same thing.

Just track your fuel used in the DIC (if you have one)

It's accurate enough to trust somewhat

I've been doing this for 2 yrs now.

I've heard dropping the tank can be a real pain, so I

am in no rush to change the sending unit.

RockySierra · August 31, 2011

The less fuel in the tank the better when changing the sending unit. This was a VERY common problem on the GMT-800s and prior vehicles. With doing the fuel sending unit, your replacing the pump and the thingie that reads the fuel level so you kill 2 birds with 1 stone as the fuel pumps don't generally last very long in the GMT-800s.

Just a FYI, try to avoid driving with a tank below 1/4 as the fuel also serves as a way of cooling the fuel pump/sending unit. If the pump gets too hot, that leads to premature fuel pump failure. Something I learned about 8 or so years back when everyone on here had GMT-800s and had the same issues

jdaniel83 · September 1, 2011

Thanks for the advice. I don't have a DIC on my '01 but I've been going off of mileage so I'll keep doing that for a little while till I have the chance to replace the sending unit. I was told that the pumps for the Duramax's were different and that the sending unit could be replaced without replacing the whole pump assembly. Is this true?

jdaniel83 · September 4, 2011

Anyone have any ideas on whether the sending unit can be replaced seperately from the fuel pump assembly?

RockySierra · September 5, 2011

not that I know of. They are all part of the same unit from what I understand.

hd01chevy · September 5, 2011

my 01 with gasser had same problem, except my fuel guage would bounce all over the place......i changed just the sending unit on mine, which included cutting the main harness and put on an updated plug on since it for some reason was changed...

jdaniel83 · September 6, 2011

Thanks for the responses. I'm going to look into getting the fuel sending assembly and hopefully just change it out.

Sierra6.0 · September 6, 2011

my 01 with gasser had same problem, except my fuel guage would bounce all over the place......i changed just the sending unit on mine, which included cutting the main harness and put on an updated plug on since it for some reason was changed...

My GMT-400 Gen1 Vortec is having a bit of a stumbling issue that could either be the injection spider or fuel pump (I'm getting a fuel guage today to potentially eliminate the pump as part of the problem). Anyway, while researching I noticed that most 3rd party replacement fuel pumps contain a new wiring harness. Apperently the original GM harness has too small of wires which helped with over-heating when the pump was drawing full amps. The redeisgned harness was designed to handle the load better and give you more fuel pump life. I wonder if your '01 pump was similar.

The question I have, relating to the original topic:

Is it easier to drop the tank, or slide/lift the bed?

jdaniel83 · September 7, 2011

Well I've actually replaced the fuel pump in 2 different gas trucks but never in a diesel. The first time I dropped the tank and the other time I lifted/slid the bed back enough to get to the pump. The lift/slide method was a little easier but only because I had someone to help me lift and slide the bed back. I imagine and hope it will be the same or a similar procedure with the diesel as it was with the gas.

jwm65 · September 7, 2011

Thanks for the advice. I don't have a DIC on my '01 but I've been going off of mileage so I'll keep doing that for a little while till I have the chance to replace the sending unit. I was told that the pumps for the Duramax's were different and that the sending unit could be replaced without replacing the whole pump assembly. Is this true?

i have been going off of trip since 2004 on my 2001