suction in fuel tank

[bazz61]

how much suction should there be after a 3 hour run from full tank, the DX ute 4.2 took a good breath when releasing the fuel cap today on a run from gladston to gold coast, and how do you go about checking fixing the breather pipe... thanx in advance and merry xmas to everyone, cheers barry

[MudRunnerTD]

There really should not be any suction. There is a Pressure Relief Valve on one of the lines coming out of the top of the tank. Its an inline valve and small. Not sure on the Ute but on the Wagon it is in the rear Right Wheel well just on the inside of the Chassis. Take off the inner rear guard section and you can reach it. Maybe take your breather off the top of the tank and blow some air through it.

This has the potential to be a big problem long term as there is No Non return valve between the tank and the pump so that vacuum is sucking off the back of the pump.

[bazz61]

thanx for that, barry

[brisz]

On the 300ZX the fuel cap has a releif vavle in it, sucks in through the cap and expels through the carbon canister. This can happen if you have a non releif cap on a 300ZX.

Only one i have seen, so not exactely common.

If you are getting just a little suction (think yourself lucky) not a problem but if you are getting a huge ammount maybe worth a closer look.

http://www.aus300zx.com/forum/showthread.php?t=279159