Tomkat80222

Last fall when the weather was over 80 degrees, I would get a smell of gas at the rear of the car. It seem to get worse when there was more gas in the tank. I messaged with Greg B about this and he said,

"It sounds like you may have intake vacuum sucking on the fuel tank. Somewhat common.

This condition will "suck" the fuel tank down and cause the fuel to boil at low temperatures."

He was going to get me additional information on what to look for and I have tried to get ahold of Greg again, but have not heard back. I'm getting ready to change the coolant and wanted to tackle this at the same time. I have searched, but not found any solutions.

Shark_gts

Actually the opposite. Fuel expands like crazy with temperature - increased pressure forces vapours out of any system leak. Supposed to be a closed system with vapors going to the cannister.

So you either have a loose hose/clamp up top, crack in your tank in the fender well or there is a seal issue perhaps (at the hatch access)

FredR

If the tank breather system fails open and too much vacuum is applied because the evacuation system is open longer than it should be, then indeed a vacuum canbe applied to the tank and it does not take too much vacuum to cause the tank to collapse. If this happens one has to wonder whether tank integrity will be lost and if so, where is the most likely point of failure. For there to be a smell of gasoline at the rear of the car there would logically have to be some leak path. If the leak path is high up or in the filler down pipe, then one might not see leaking fuel. If the leak path is below the wetted level, then you would expect to see a leak. You say the problem is more noticeable when the tank is full - is that a clue?

As the car is driven, the fuel is circulated into the engine compartment and returned to fuel tank via the fuel cooler which is cooled by the a/c system. The system generally heats up and as it heats the vapour pressure will increase and more vapour will be generated. The vapour system has two valves in the engine bay, the first one is opened[?] by vacuum in a valve that sits under the coolant expansion tank, and the other valve is on the front of the engine just below the filler neck extension and this is electrically operated although by what criteria I do not know. Both these valves need to operate for the system to vent.

Finally, the fuel return line to the fuel tank should be checked for signs of any leakage.

Trust the above gives you some food for thought.

Mrmerlin

I would take a look at the tank and see if you find any traces of fluid dripping,
if so then their is a good chance the transfer hose has sprung a pinhole leak.

NOTE if the vacuum valve at the front of the engine has failed then this will cause the tank to implode, a few cycles of the tank moving this way can cause the plastic in the tank to fracture,
this can also cause fluid weeping and usually a replacement tank will be needed as the fracture line could be long.

Also worth a look remove the fuel pump cover and inspect the pump filter assembly for weeping, sometimes the check valve comes loose a bit and can cause a slow drip of fuel while in operation.

Also inspect the 3 way connector under the RF fender liner,
if this is broken then fuel vapors will not be cycled into the intake, this can cause fuel smells.

Inspect the tank sender and its return line its getting time to replace the tank return line and the transfer hoses

worf928

Is the fuel smell from the inside? Or the outside? If the former:

Is there anything fixed to the right side of the deck in the hatch area? A big audio amp? CD changer? Or, perhaps there used to be one?

Randy V

Yeah, that happens with That Guy when he gets busy.

My go-to communication method with him is telepathic thought transmission.

Tomkat80222

Thanks for the responses. The smell doesn't happen unless the temperature is warm. I think it may be the return line. I smell the gas at the rear, never upfront. It's somewhere around the tank. I was also having some higher running temperatures and replaced the thermostat, collant and radiator cap. The new thermostat runs a bit cooler. I tested the old thermostat and it opened, but not as much as the new one. Is it possible the hotter conditions in the engine compartment is heating the return fuel line creating increased pressure?