1999 RX300, 234K, original owner. The fuel tank has a capacity of approximately 17 gallons. The low fuel light has always come on with about 3-4 gallons of fuel remaining, and would always let me drive 50-60 miles before 'running out' which I didn't let happen very happen but in 18 years it did. Now, however, within 10 miles of the light coming on the car runs out of gas, despite that there is still at least 3 gallons in the tank. Why? TIA.

 

Your fuel level float may have been sticking and gave you an inaccurate reading

 

As far as the low light you can have two problems.
1. With enough gas it comes on
2. It comes on with very little gas left.

What is the actual capacity of the tank and then there is a usable capacity. The max I have pumped in was about 15.5 gallons and I was thinking that I pushed it too far.

For good health of the fuel pump, try not to go below 1/4 tank.

Jab, what is your basis of the claim that there is still 3 gallons in the tank? And yet you run out of fuel.

Fatnoypi has identified the easiest of all things ... replace the sending unit.

Diagnosis can be done if some one has the range of resistance to check by moving the float.

If you have been buying gas from a reputable station(s) then dropping the tank down and giving it a thorough cleaning may be an overkill.

Salim

 

Thanks guys but I'm pretty certain about the fact that the light consistently comes, as it always has as long as I have owned the car, with three gallons still in the tank. How do I know? After one of these recent 'incidents' I immediately fill up the tank and it takes 13-14 gallons, no more, yet the car won't run until I have added fuel. In other words, I don't think its the sending unit that is sending false information; I think it is the pick-up that no longer reaches as deep in the tank as it used to.

 

just a theory that it may have enough sediment that at low fuel levels, the pump cannot draw enough flow to feed the injectors.