Engine noisy when tank is low(!?!!?!)

You could try checking the fuel pressure with a full and near empty tank and see if there is a difference. That would be my first step. And yes if your pump is shot or fuel filter inside the tank is clogged you need to buy a new fuel tank. 77001-47090. Tracy Toyota internet price is currently 452.41 new. Or you could get a used one.

 

How LOW do you let it GO ??

The extra noise could be coming from a failing fuel pump......which you don't hear as long as it is immersed in fuel.

 

Do you mean the first dot? 1 dot lit? That’s pretty low, Prius gas gages are not known for their high accuracy. 9 gallons is a lot but I can’t say if you were about out of gas or not. You were pretty close though. Does it make the sound when you have 2 dots of fuel left?

 

Fuel pressure check then.

 

I don’t think there is a schrader valve to check the fuel pressure. You have to tap in. I’m sure someone here will post the procedure.

@SFO

 

I doubt its got anything to do with fuel level whats probably happening is the hybrid battery may be tdying and when that happens only thing left to power the car is the tiny little under powered engine. The engine will be screaming to go anywhere. I suspect the hybrid battery is bad because that's like the #1 reason people dump there used G2.

Next time it starts doing it monitor the battery level on the mfd. I bet the battery is in purple which is basically empty.

Or just watch the battery level....if it goes from blue to purple real fast and will not go back into blue within 2 miles its time for a new battery or a rebuild.

 

Why would you think it’s the battery when the fuel gets lower? If anything it would be opposite. The car gets lighter as the gas tank empty’s

 

You really need to check your fuel pressure. I guess best way would be to check it at home when the gas tank was almost empty, then throw like 2 five gallon gas cans in and see what the pressure reading is then. Plus I was not kidding about the gas gage. Plenty of posters here have run out of gas on 2 dots. The gas gage on a gen 2 prius is more of guess than anything else. It’s the stupid fuel cell. Even NASCAR has troubles with it. And they get millions to work it out.

 

If you ran diesel, I'd say you were sucking water from the bottom of the tank.

 

Is the gas station at the top of a hill? I mean I don't think it's that simple, but technically that would explain things.

 

Regardless of the noise you are trying to identify......THIS is a BAD habit and you need to work on changing it.
Someday it will bite you in the butt and the engine will go completely quiet......when it runs out of gas.

 

@Ianmeister my car does this as well..I am fairly sure what is actually happening is that there is an exhaust leak that is less apparent when there is more weight in the back (i.e. full tank). Did you solve your problem?