Hey guys, I filled my tank up yesterday afternoon and my fuel gauge was reading full tank like normal. When I got in my truck this morning the tank was reading 1/4 tank! I had only drivin 50 miles, and as I was driving the guage started to slowly drop and now is just stopped at empty.

so my question is, is there a fuse that might have gone bad, a sensor, or do you think the guage just took a crap on me? I have never had this happen to me so, I would like to fix it myself rather than take it to the dealer and spend lots of $. any help would be appreciated.

thanks

 

well i know with the 1st gens it is a common problem that the sending unit gos bad or comes apart and gives the wrong reading.
i have to gauge how much gas i have by my milege and fuel light.

 

This thread might help you better understand the inner workings of the in-tank FSU. Your problem sounds pretty extreme though. But it does sound like the FSU took a dump somehow. It almost sounds like the float/arm got stuck in the down position...

Are you still under warranty by any chance? If you end up going to the dealer, I highly recommend Tempe Toyota (ask for Jason Briggs if he's still there).

 

It might not be your FSU but your Fuel Gauge mounted in your dash. The Analog gauges works by polarity and magnetic attraction through coils in the gauge. Disconnect the wires from your Fuel Gauge in the dash and supply power and ground to them. Straight polraity should read Full, reverse should read Empty. If you supply straight polarity and gauge still reads 1/4 tank than it's your gauge. The float on your full pump is a variable resistor. To test that still disconect the wires leading to your FSU do the same thing as the fuel gauge, supply power and ground. Once again straight polarity should read full on fuel gauge, reverse should read empty(if gauge works correctly).

 

Sender should read 3 ohms full, 110 ohms empty:
http://www.4crawler.com/4x4/4R_TechI...tml#Electrical

 

Drive it and then fill it back up and keep an eye on it. If the same problems then yes it could be your FSU, but also keep in mind the other contibutors that are even listed in the 99-00 4Runner TSB EL010-00 -circuit card (or just the gauge), fuel pickup tube