Fuel level

Hi guys, I am new to the forum but I have a question
I have a 1995 BRMW all stock, only thing that has been done is the fuel pump and sender was replaced.
The problem is that when I put about 10.5 gallons of fuel in it it shows that it is full. But if I am not mistaken, that car has a 21.9
gallon tank. When it is empty (which is not very often), the gas light comes on so I have no clue what the problem is.....
Thanks for you input

This is the GM standard readout of your gas gauge. Everybody complains about it. There are ways to improve the readout, but it is easier to get used to it, and compensate mentally than to fix it. Fixing it requires modifying the potentiometer on the sending unit. That means dropping your tank. The instructions are either on this forum, or on impalassforum.com.

mrmajjikk wrote:

only thing that has been done is the fuel pump and sender was replaced.
The problem is that when I put about 10.5 gallons of fuel in it it shows that it is full. But if I am not mistaken, that car has a 21.9
gallon tank. When it is empty (which is not very often), the gas light comes on so I have no clue what the problem is.....
Thanks for you input

If you didn't have this problem before the new fuel pump and sending unit, I would say something got bent.

Tom

Actually, when I first purchased the car that was the problem. I replaced the pump and the sending unit...

For what its worth Ive never got more than 18 gallons in the tank,and Ive run it completely dry!

When I fill my RMS the gauge goes far to the right of full. When it reads 3/4 it is down to half a tank. When it reads 1/4 it actually has about 1/4. When the little yellow light goes on I have about 50 miles left. Once I learned its foibles there was nothing to be gained by fixing it as it is consistent.

I suggest filling it full from various positions of the gauge and memorizing the critical points.

GM learned a lesson with the first digital fuel guage it put in Cadillacs. They made it accurate from Full to Empty and dealers got bombarded by complaints about gas mileage sucking because the guage would drop pretty fast from full. People used to the old guages staying above 3/4 for most of the first actual 1/2 a tank thought the cars were total gas hogs, same type of person who NEVER actually figures out their true mileage. GM soon changed the digital guages to stay nearer to full for a lot longer to mimic the old analog guages and the complaints stopped.

just me wrote:

GM learned a lesson with the first digital fuel guage it put in Cadillacs. They made it accurate from Full to Empty and dealers got bombarded by complaints about gas mileage sucking because the guage would drop pretty fast from full. People used to the old guages staying above 3/4 for most of the first actual 1/2 a tank thought the cars were total gas hogs, same type of person who NEVER actually figures out their true mileage. GM soon changed the digital guages to stay nearer to full for a lot longer to mimic the old analog guages and the complaints stopped.

Is this accurate for everyone? When the light comes on you've got about 50 miles left? That seems excessive. Normally when my light comes on I'm at the "E" already!

Andebe wrote:

For what its worth Ive never got more than 18 gallons in the tank,and Ive run it completely dry!

MORON! Just kidding,only ran mine low enough to set off the low fuel alert maybe 3 time and it took around 21 gals to fill it back up and I don't keep filling after the pump cuts itself off.My gauge reads the same way too!

Since I replaced the tank straps, the guage never goes to completely full anymore. Stays under it and to get to the "normal" 400mi before filling her up again (the car that is) i drive till i'm way in the orange low fuel (i don't think the 93 Cappie has a warning light) Fuel consumption has not changed.

The Caprice should have a fuel warning light, and a chime warning as well. Depending on the low end of the resistance scale of the level sender, it may not trigger the chime or light.

Well the risk is running it dry. But i'll have a look, the light must come on as you turn the key? (as all of the dash lights)

Check to see if you have the multi function chime module. The FSM has the troubleshooting chart. If you do not have the FSM, the 92 is identical, and there is one on ebay cheap.

I'm kinda glad this got brought up. After my 89 Buick Electra got towed and had its 2nd transmission fiasco, the gas gauge became a bit wonky.

On a full tank, the gauge would go past Full and stay there for a while (150-200 highway miles). It rarely reached Empty. Now, it barely touches the full mark and goes to Empty much quicker. I have about half a tank left at empty now, so I've been using my tripometer for gas trips.

Kinda annoying since it was so good beforehand. Was curious how to go about fixing it.

The gauge reads resistance from the sender. The higher the resistance, the more full the gas tank is. If you have a weak short in the wire, it could make a parallel path to ground, and make the gauge think the sender is at a lower resistance. Other than that, the sender may have the coil stretched toward the bottom, and it never sees the one end of the potentiometer.

I think you are all mistaken. My tank has a little Leprechaun in it. He floats around in there and sends the signal. Now that we have ethanol in the fuel he is drunk most of the time and can't be trusted to stay on the job. Yet another unintended consequence of political folly...

rjathon wrote:

I think you are all mistaken. My tank has a little Leprechaun in it. He floats around in there and sends the signal. Now that we have ethanol in the fuel he is drunk most of the time and can't be trusted to stay on the job. Yet another unintended consequence of political folly...

Your leprechaun must be a democrat!