Fuel Gauge Sending Unit Design Question

[mtbtim]

Hey Dudes,

I know there's other related threads to this topic but I wanted this thread to answer a simple question. Did the Toyota Engineers design the fuel gauge sending unit to show empty when there's approximately 4 gallons left in the tank as a safety buffer so you have plenty left in reserve to make it to the next gas station? I have a 98 and 00 and both rigs only take around 14-14.5 when the dash gauge shows near empty and the light is on. I have a friend with a 97 and his is the same as well. Ideally, I'm hoping somebody who's been a 3rd Gen owner since Day 1 to chime in and let us know if the tank has ever taken close to 18.5 gallons when the fuel gauge first shows empty and the light comes on.

If this wasn't how it was designed, can it be fixed with a new sending unit?

I also know there's a TSB for the 99 and 00 models that involves replacing a circuit board in the dash and the sending unit. The fuel gauges on my rigs for all intensive purposes seem to work correctly other than the fact it shows empty with quite a bit of fuel still left in the tank.

 

[TheDurk]

You will never get 18.5 on a refill from an honest pump. I did get 18.5 starting from a bone-dry tank that had been out of the truck and POR15'd while I did the frame swap detailed in the thread linked in my sig. I added 5 gallons to start up and then slightly over 14 gallons at a fill-up six miles away and after a five-mile test drive. Allowing for 11 miles of driving and for refilling all lines and the fuel filter (all also totally dry), it pretty much adds up to an 18.5 gallon tank.

I had drained the tank using the fuel pump and I was unable to get the last 100 ozs. out. I measured, just out of curiosity. It is easy to imagine a moving vehicle would need more than that to maintain suction--two gallons is the popular estimate.

On some years the vent-pipe is longer than in others, notably '99 and '00. You may get more in by switching to the updated version of that part with the shorter pipe.

I tried shortening my pipe, but I seem to have overdone it as I leak to the ground when filling really full. Still figuring this part out. I hope to pull the tank again this summer.

 

[mtbtim]

Thanks for the reply [MENTION=10169]TheDurk[/MENTION]. I think I won't mess with it then.