New Pump & Sending Unit but Gauge Still Fluctuates

[blk95lumina]

Hello.
I have a 95 Lumina 3.1L w/ ~155K mi.
The fuel gauge has always moved erratically whenever making turns, accelerating, and braking since I have had the car for 2 years.

I recently replaced the fuel pump and sending unit in the tank.
Surprisingly, my fuel gauge still reads erratically as I make turns, etc. even with the new sending unit. It reads accurate and steady so long as you are driving straight. The wires at the sending unit seemed fine, although I did not trace them all the way to the instrument panel.

Do Luminas around this year usually have sensitive gas gauges/sending units which fluctuate as you turn, etc.?

This is the first Lumina I have owned and driven.

Thanks.

[kevinb70]

cliff notes version: new i/p cluster assembly, reprogram eeprom on car. TSB recommendss replacing fuel level sensor on all but lumina and monte carlo



File In Section: 06 - Engine/Propulsion System

Bulletin No.: 99-06-03-007C

Date: April, 2001

TECHNICAL

Subject:
Fuel Gauge Inaccurate/Fluctuates, Premature Low Fuel Chime (Exchange Instrument Panel Cluster, Replace Fuel Level Sensor, Reprogram EEPROM)

Models:
1997-99 Buick Century, Regal
1997-99 Chevrolet Lumina, Monte Carlo
1998-99 Oldsmobile Intrigue
1997-99 Pontiac Grand Prix

This bulletin is being revised due to part number changes and deletion of the parts table. Refer to the parts information catalog for the correct part number. Please discard Corporate Bulletin Number 99-06-03-007B (Section 06 - Engine).

Condition

Some customers may comment on the following conditions:

^ The fuel gauge reads incorrectly.

^ The low fuel chime sounds prematurely. For example the chime may sound when 19-22 L (5-6 gallons) of fuel remains in the tank.

^ The fuel gauge may fluctuate from full to empty and then back to full after a fill up and a hot soak.


Cause

These conditions may be caused by several factors which are vehicle specific:

^ Fuel contamination to the resistor board (sender card) of the fuel level sensor in the fuel tank.

^ Calibration changes within the EEPROM of the PCM.

^ Software revisions to the I/P cluster.


Each of these factors affect the accuracy of the fuel gauge and/or the low fuel warning system.

Correction

1998 Oldsmobile Intrigue vehicles built prior to May 7, 1998.

Request an exchange I/P cluster from the A-C Delco(R) Service Center. This cluster must contain the software modifications in Delco Electronics Bulletin # 98 IDPD07ISA.

Installing this new cluster will result in the elimination of the low fuel chime.

Important: You must advise the customer about the elimination of the low fuel chime, as this is a change to the Owner's Manual information.

All 1997, 1998 and 1999 vehicles built prior to December 1, 1998.

In order to improve the accuracy of the fuel gauge, replace the fuel level sensor in the fuel tank. Refer to the procedure in the Engine Controls sub-section of the Service Manual.

1998-99 Oldsmobile and Pontiac vehicles built prior to October 1, 1998.

Reprogram the EEPROM using any Techline CD numbered higher than CD # 21 for 1998 or the TIS 2000 # 12 CD or higher.

Parts Information

For the correct part number for the fuel sender card, refer to the appropriate Parts Information Catalog.

[blk95lumina]

Thanks.

How do I reprogram the EEPROM?

If it is the cluster, then I'll live w/ it unless the gauge just dies.

Thanks.

[kevinb70]

Originally Posted by blk95lumina

Thanks.

How do I reprogram the EEPROM?

Probably by paying someone, like I would since I don't have a multi-thousand dollar tech2 or whatever scan tool. Ask first to see if a flash would even fix the problem.

Simplier is use odometer to measure the distance you can go on a full tank in the city, then highway. fill up by resetting tripmeter (fillup @ 200 city, or 250 highway) also know that when sitting still your gas guage is correct?

my gas gauge varies, might be at 1/4 then going downhill it goes toward E... i live with it. but it is more accurate when driving straight and level.

[99MonteCarloZ34]

I would like to know (sorry for interrupting your thread with unrelated topics) if there is any gauge cluster from a new monte carlo or different chevy/gm model that will fit a 99 monte carlo? If anyone knows it would be a huge help!

[master87]

actually i would check the fuel send float there is 2 needles on the board check to make sure they are touching if not thats your problem they wobble off and on push the pins back on the board and test to make sure thats the problem

[Tech II]

Master87, that post is almost a year old....but he replaced the sending unit.......so I doubt that was the problem....

Funny, someone posted a TSB that did not apply to the vehicle involved...

Since the pump and sending unit were replaced, the other possibilities were a bad connection in the circuit, a bad cluster(some clusters had a "buffer" built into the fuel level circuit to prevent this), and it could be a bad fuel tank......he had only owned the this vehicle for two years, and the problem was already there........so something could have happened in the 13 years prior to him getting the car.....

Ran into a crazy one years back.....same problem......erratic gage......I jounced the rear end and the gage was all over the place....said it needed a sending unit....customer said in the last 3 months, it had a new tank, pump, and 3 sending units installed......Quick road test and it was all over the place.....backed out the sending unit wires from the harness, and I think I attached a 45 ohm resistor, and the gage showed half full.....road test and steady as a rock....so the problem was from the harness in.....dropped tank, removed pump and sending unit, and nothing wrong, electrically......and then I noticed it......looking inside the fuel tank, guess what was missing? There was no baffle in the tank......so that float was sloshing all over the place.....new tank fixed the problem.....