I'm just curious about the old style sender/pump assembly. When I bought the car at 78,000 miles I noticed the classic symptom of the gauge only going to the 3/4 mark. Since then, (now at 86,000) I have pretty much ignored it 'cause it seems accurate enough after it passes 1/2. The question is.....what happens next? Will it get worse, fail completly or stay the same. I am not inclined to change it just to see a little higher reading when full.

tks all

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Litton
'90 420 SEL (sold)
'72 280 SEL 4.5
'98 ML320 (for sale)
'86 560SL
'05 Jeep Grand Cherokee Ltd (offroad in style)
'87 Chevy Blazer (AZ Pin Strips)

I have a 98 ML and the fuel gauge never showed completely full. Moreover, the tank was empty when the pointer first touched the lower white bar in the gauge. This situation continued without any problem from the fuel pump. Do not fix it just for this minor irritation. While under warranty, we had the dealer try to fix this problem, but it was never fully corrected.

However, I then had to replace the fuel filter as I was approaching 130K. I read all of the threads on the task and did it myself. In the process, I unplugged the fuel pump and noticed blue corrosion on the 12+ Volt contact. When I reattached the plug, the pump was not working. Ultimately, the fuel pump failed and I replaced the sender/pump and the wiring harness. The new pump has an arrow molded into the white plastic, and this marker should line up with an indentation in the fuel tank. The mark should be pointing across toward the right side of the truck. For minor adjustments, when looking down at the fuel pump and after loosening the big plastic ring which secures the pump by one full turn, twist the pump counterclockwise a few degrees to raise the gauge closer to the full mark on the gauge.

Sorry to be so long-winded.

Thanks, I appreciate the info. I don't think I will replace it just yet. Funny thing, as the needle moves past 1/4, the low light comes on and if I do a refill, it is dead on where it should be.....adding the amount to fill by the manuals stated reserve which is where the light comes on.

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Litton
'90 420 SEL (sold)
'72 280 SEL 4.5
'98 ML320 (for sale)
'86 560SL
'05 Jeep Grand Cherokee Ltd (offroad in style)
'87 Chevy Blazer (AZ Pin Strips)

I run my fuel tank empty and then I fill it up to the max. I never had any trouble until my gauge showed half full. Some one on your sight explained on how to reset the fuel gauge by unplugging the connecter at the left/diver side, forward of the rear wheel. Then turning the key to on (but not starting the vehicle) and then plugging it back in. It also stated that it resets the logic. It worked great. THANKS. What the logic does is that it keeps the gauge from bouncing around with the fuel level. I ran a little test, gauge works fine for a while. But when I fill my tank up with my key in the on position or with the vehicle running so I can watch the gauge go up as I’m fueling, the logic system seems lock up and cause the error. Fix for the fuel gauge error (at least for me), Reset it and fill it with the vehicle in off. Its been working. Good Luck.