2001 4runner. v6, 250k. I've had a code for evap emissions for 9 months now. Replaced the Canister last year, which gave me all of three months without a check engine light.
The car has to be warmed up, with 10-15 minutes of driving. When the gas pedal is touched, the car makes a rather trumpet like noise in the back. I bought a diff rebuild kit thinking that was the problem, but yesterday my dad and I figured out that the diff is quiet. Its the gas tank. taking off the cap doesnt change anything. The car has to be under load to make the noise. When idling its completely quiet. Speed doesnt change anything.
I tried to search for similar issues on vehicle specific forums, and nothing came up. I'm at a loss with this one.
Go over all of the fuel line connections and vacuum hoses on the tank. There are probably 3, at least, going to the tank. Feed to the motor, return to the tank (unless it has an in-tank regulator,) evap line to the charcoal canister, and on the RAV, at least, there's one that goes from the tank to almost all the way up the filler spout. There could also be a left-right small hose, connecting both sides of the tank at the top, depending on the tank. And the filler spout has hose clamps on it too, which could be loose and causing noises if flapping when under pressure. If all those are good, pull the fuel pump access panel and look for something loose or rattling in there, and the gasket itself.
I don’t see how it could be anything other than the fuel pump, but I can’t figure out how or why it could be make that noise.
Is it any different with a full or empty tank?
pjbgravely said:
I don’t see how it could be anything other than the fuel pump, but I can’t figure out how or why it could be make that noise.
Is it any different with a full or empty tank?
Doesn't make a difference. My thought is fuel pump as well, but wht would a fuel pump care about load? That's what throws me off.
It cares about load because they probably do some sweet PWM motor control so the pump isn't running full-bore all the time. Now, think about making trumpet noise with your lips. What actually makes the sound? Your lips vibrating as a pressurized fluid escapes past them. What changes the tone? Changing the pressure. I'm going to guess the failure is in the tube / pipe / whatever on the pressure side of the pump, inside the tank. Probably has a small split in it that only trumpets when operating pressure is high.
