Screwy fuel gauge question

heavy4x4 · June 13, 2005

Hi,

I'm new here and not sure where to post, but this seemed like a reasonable choice. Please move to the correct forum if this doesn't belong here.

I just bought a 2000 Chevrolet Silverado 1500 4x4 Z71 Extended Cab Short Bed about 2 weeks ago. It has 128,000 on the ticker and runs very well. I have noticed some issues with the gas gauge however...let me explain what I've seen.

-Sitting in park, sometimes the gauge will fly up to full and then down to empty and back to where it should be...all jerky motions

-about 75% of the time I start my truck, the fuel gauge will read empty and remain there (turning on the "low fuel" light). If I start driving it will S L O W L Y creep up to where it belongs.

-I just filled the tank up to the top yesterday and drove about 60 miles on the interstate. During the trip, the gauge would randomly change from reading full to empty (no where in between).

-Today I noticed that when I start my truck and the gauge reads empty, that if I put it in gear, move forward a bit, and then slide it into neutral, the gauge will jerk up to where it should be.

Any ideas? I've read some stuff about the sender being a bad design and getting junked up with sulfur. I added GM's fuel treatment this past weekend with little change in gas gauge performance. I also read something about a "module" of some sort in the engine compartment that has control over the gas gauge.

What do I need to look at/change to get rid of this problem. I can live with it, but I prefer not to.

Also, if you feel it's the sender, does that mean the fuel pump is about to go?

If it is the sender, can I get the part number for the sender? Can I just replace the sender and not the whole pump unit?

Thanks for all help!

-Steve

heavy4x4 · June 21, 2005

A couple more details on my on-going issue.

I'm now starting to think it's the module moreso than the sender itself...what do you think?

1) The $15 GM fuel treatment didn't do anything.

2) When I fill up my gas tank to the top, my gauge stays at empty for at least 20 miles and there's nothing I can do to make it come off empty and a "low fuel" warning light. (this lends to me thinking it's a bad sender...but, read #3)

3) Whenever I turn on my truck after this initial 20 miles after a fill-up, the gauge is almost always on empty with the low fuel light. All I need to do is pull out of my parking spot, drive 10 feet, and then slide the shift lever into neutral...at that point I watch my gauge go up to the correct level almost instantly.

Does that sound like module or sender?

Thanks.

71GMC_3/4T · June 13, 2005

I've heard these gauges are overdamped when you're in gear to prevent annoying fluctuations. The damping is shut off when you are in park, presumably so you can watch the gauge when you're filling up.

The first thing I'd try is a can of BG-44K fuel system cleaner and a bumpy road. It might clean the sending unit enough to make it start working again. Yeah, it's pricey (~$22 / can), but your injectors probably need cleaning anyway. If it doesn't work, you're probably going to have to put in a new sending unit. I'd shotgun the fuel pump while you have it apart, if you got the extra cash and time.

Welcome to the board!

shelbytt · January 16, 2006

Hye I seen your post and was cutious what you did to fix it? Did you replace the sending unit? I have a 2000 Chevrolet Silverado 1500 Z71 with the exact same issue.. Let me know Thx [email protected]

Hi,

I'm new here and not sure where to post, but this seemed like a reasonable choice. Please move to the correct forum if this doesn't belong here.

I just bought a 2000 Chevrolet Silverado 1500 4x4 Z71 Extended Cab Short Bed about 2 weeks ago. It has 128,000 on the ticker and runs very well. I have noticed some issues with the gas gauge however...let me explain what I've seen.

-Sitting in park, sometimes the gauge will fly up to full and then down to empty and back to where it should be...all jerky motions

-about 75% of the time I start my truck, the fuel gauge will read empty and remain there (turning on the "low fuel" light). If I start driving it will S L O W L Y creep up to where it belongs.

-I just filled the tank up to the top yesterday and drove about 60 miles on the interstate. During the trip, the gauge would randomly change from reading full to empty (no where in between).

-Today I noticed that when I start my truck and the gauge reads empty, that if I put it in gear, move forward a bit, and then slide it into neutral, the gauge will jerk up to where it should be.

Any ideas? I've read some stuff about the sender being a bad design and getting junked up with sulfur. I added GM's fuel treatment this past weekend with little change in gas gauge performance. I also read something about a "module" of some sort in the engine compartment that has control over the gas gauge.

What do I need to look at/change to get rid of this problem. I can live with it, but I prefer not to.

Also, if you feel it's the sender, does that mean the fuel pump is about to go?

If it is the sender, can I get the part number for the sender? Can I just replace the sender and not the whole pump unit?

Thanks for all help!

-Steve

<{POST_SNAPBACK}>

GM-Tech · June 21, 2005

Does that sound like module or sender?

Understand that the "module" is just a big plastic can lookin' thing that holds the fuel pump and the fuel level sender and a few fuel lines and wiring. It's not an electronic module and in no way affects the fuel gauge. Well, I suppose if the plastic broke and interfered with the float arm, yeah, then it could, but I have never seen anything like that happen. On some models, if you buy the module, you don't even get the fuel level sensor with it!

Your problem is most certainly the fuel level sensor. Replace just that unless you have money to burn.

heavy4x4 · January 17, 2006

I have done nothing about this issue, except I have learned the following things.

- I get the "Low Fuel" message mostly when the tank is freshly filled. After about 20 miles of driving, the gage starts reading accurately.

- If I put the truck in park, the fuel gage will drop to empty after about 1 minute...not a big deal.

- If at any point after the initial 20 miles after a fill-up I get the low fuel message, I only need to put it in neutral (while moving) and it will read properly. Most of the time I don't even do that...I just ignore the message.

Every time I fill up, I reset my trip-odometer. When I get to about 330 miles, I know it's about time to fill up again (usually end up putting about 20-22 gallons in the 27 gallon tank).

My advice is go off the odometer if yours is doing the same thing. I know it's hard to see a gage needle go flying one way or another when you're driving and have a warning light come on (still sends a shock through my body of..."what was that!"), but, for as much time and money it costs to replace, you're better off waiting until the fuel pump fails to replace the sender module.

-Steve

lucky13 · June 15, 2005

it needs a fuel level senser about $150.00 gm list

i would recommend changing the whole pump though with that milage all though it is a little pricey

if you do it yourself (not that hard)

remove the bed dont drop the tank its alot easier that way

good luck

heavy4x4 · June 21, 2005

Does that sound like module or sender?

Understand that the "module" is just a big plastic can lookin' thing that holds the fuel pump and the fuel level sender and a few fuel lines and wiring. It's not an electronic module and in no way affects the fuel gauge. Well, I suppose if the plastic broke and interfered with the float arm, yeah, then it could, but I have never seen anything like that happen. On some models, if you buy the module, you don't even get the fuel level sensor with it!

Your problem is most certainly the fuel level sensor. Replace just that unless you have money to burn.

<{POST_SNAPBACK}>

Thank you for you input. I apologize...I was under the understanding that the "module" was an electrical circuit up in the engine compartment somewhere that received information from the sender and sent it to the dash. I'm not sure where I got that from though.

-Steve

P.S. Do you have the GM part number for just the sender? My local dealer only saw the whole fuel pump/sender assembly. Vehicle: 2000 Chevy Silverado 1500 4x4 Z71 extended cab short bed (27 gallon tank, I believe).

DEV1ST8R · June 15, 2005

Fuel sending unit. . .MANY chevy owners have the same problem. It's an easy fix if: 1.) You have the part, and 2.) You take the bed off

GM-Tech · June 21, 2005

Well, the fuel sender does send the signal to the PCM, so that's a module. But I've never seen one of those cause a fuel gauge problem whereas as the sending unit causes this by the score.

Here's a TSB on this issue. Part numbers for the sensor only are near the end.

Cranks But No Start, Stall, Inaccurate/Incorrect Fuel Gauge Reading, No Fuel, Vehicle is Out of Fuel and Fuel Gauge Reads Above Empty (Replace Fuel Level Sensor) #04-08-49-018E - (Jan 5, 2005)

2001-2004 Cadillac Trucks

1999-2004 Chevrolet and GMC Trucks

2004-2005 HUMMER H2

with Gasoline Engine (VINs Z, X, V, T, U, N, G,6, 8 -- RPOs LU3, LR4, LM7, LQ4, LQ9, L59, L18,LK5 , L52 )

Parts are currently available for vehicles with Variable Fuel (VIN Z -- RPO L59) vehicles. Please refer to Corporate Bulletin Number 04-06-04-012B or newer for Variable Fuel (VIN Z -- RPO L59) vehicles.

This bulletin is being revised to include information on the Chevrolet Colorado and the GMC Canyon. Please discard Corporate Bulletin Number 04-08-49-018 D (Section 08 - Body and Accessories).

Condition

Some customers may comment on the vehicle stalling and will not restart, vehicle ran out of fuel, vehicle appears to be out of fuel but the fuel gauge reads above empty. The fuel gauge may read 1/4 tank.

Cause

Contamination on the fuel sending card may cause inaccurate/incorrect fuel gauge readings.

Correction

Follow the service procedure below for diagnosis and repair of this concern.

Confirm that the vehicle is actually out of fuel.

- If the vehicle is not out of fuel but Engine Cranks but Does Not Run, refer to the appropriate Service Information.

- If the vehicle is out of fuel and the gauge does not read empty, test the fuel gauge. Refer to the following information:

• Fuel Gage Inaccurate or Inoperative Single Tank (SI Document ID #850196)

• Fuel Gage Inaccurate or Inoperative Dual Tanks (SI Document ID #850195)

• Fuel Gage Inaccurate or Inoperative HUMMER H2 (SI Document ID #826250)

• Fuel Gage Inaccurate or Inoperative Colorado and Canyon (SI Document ID #1292631)

If testing reveals that the fuel gauge is operating correctly, replace the fuel sensor assembly and auxiliary tank fuel level sensor if equipped.

Replace the fuel level sensor. Refer to the following appropriate service information:

- Fuel Level Sensor Replacement 4.8L and 5.3L Engines (SI Document ID #1332662)

- Fuel Level Sensor Replacement 6.0L Engine - Front Tank (SI Document ID #1333086)

- Fuel Level Sensor Replacement 6.0L Engine - Rear Tank (SI Document ID #1333087)

- Fuel Level Sensor Replacement 8.1L vehicles with Front Tank (SI Document ID #1333104)

- Fuel Level Sensor Replacement 8.1 L vehicles with Rear Tank (SI Document ID #1333105)

- HUMMER H2 vehicles refer to Fuel Level Sensor Replacement (SI Document ID #861702)

- Fuel Level Sensor Replacement 2.8L Engine (SI Document ID #1220030)

- Fuel Level Sensor Replacement 3.5 L Engine (SI Document ID #1219948)

Parts Information

Parts are in limited quantities. Please DO NOT order parts for stock.

Part Number

Description

89060635

Sensor Assembly, Aux Tank, Rear

2001-2003

360364 0353, Cab/Chassis, Reg. and Ext Cab

with LQ4 or L18 and minus NQZ (with aux fuel tank)

89060636

Sensor Assembly, Main Tank, Side

2001-2003

360364 0353, Cab/Chassis, Reg. and Ext Cab

with LQ4 or L18 and without K53 (robust fuel system)

89060637

Sensor Assembly, Main Tank, Side

2000-2003

159259 0636, C/K, Long Wheel Base Utility

with LM7 or LQ4 or LQ9 or L18 and without K53 (robust fuel system)

89060638

Sensor Assembly, Main Tank, Side

2000-2003

157 06, C/K, Short Wheel Base Utility

with LM7 or LQ4 or LQ9 or L18 and without K53 (robust fuel system)

89060640

Sensor Assembly, Main Tank, Side

1999-2003

100200300 034353, C/K, 2 Dr, 4 Dr and Ext Cab Pickup

with LU3 or LR4 or LM7 or LQ4 or LQ9 or L18 and -- K53 (without robust fuel system)

2004

100 0353, C/K, 2 Dr and Ext Cab

with LU3 and without K53 (robust fuel system)

89060642

Sensor Assembly, Main Tank, Rear

2000-2003

259 0636, C/K, Long Wheel Base Utility

with LM7 or LQ4 or LQ9 or L18 and without K53 (robust fuel system)

88965384

Sensor Assembly

2004-2005

HUMMER H2

88965817

Sensor Assembly

2004-2005

Colorado / Canyon

Parts are currently available from GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation

Description

Labor Time

L1197

Sensor, Fuel Level (Tank Unit) - Replace

Use published labor operation time

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION