Fuel Filling, Fuel Filler Neck Questions (P0446, P0453)

BrianV70 · Post by **BrianV70** » 02 Mar 2018, 16:13

2000 V70 XC SE/AWD, 126,000 miles

Before I start further investigating my intermittent (but now persistant) tank filling issue, and tank venting issue (Codes P0446 and P0453), I have a question.

Is there any kind of flap or check valve where the filler neck enters the tank?

Sometimes it is so hard to add fuel (less than a quart at a time) that I wonder if there is an obstruction.

It seems to occur most often with sudden cold weather (Denver, CO) and a fuel at about 1/4 tank (I try not to let it get that low ever).

I have replaced the purge valve on the radiator shroud. I have tried fueling with the bottom hose (to the tank) disconnected. My next course of action is to look for the rollover valve, vent valve, and wherever the hose is where spiders might be nesting (I have found good threads on these topics here).

Before I tackle that, I'd like confirmation if an obstruction is possible.

In addition, there is often a very strong whoosh of air INTO the tank to releive vacuum pressure. I drive with the cap loose now so not to strain the fuel pump.

Thanks!

Post by **scot850** » 02 Mar 2018, 17:42

Blockage would be unusual. You are pointing to the normal suspects. I'd check the roll over valve as I think the will be the same as my 00 V70R. The roll over valve has a pipe that vents to atmosphere and runs up the outside of the filler tube to the inner fender near the fuel filler and has a filter on the end of it.

If the rollover valve sticks closed there is no where for the escaping air in the tank to go to and it cuts off the fuel pump with the back pressure.

I'd suggest starting there. It should be mounted on the RHS of the carbon canister and has a J hose running to it from the carbon canister. I think you can get some access from the top via the access hatch under the load area cover.

Neil.

Post by **sleddriver** » 02 Mar 2018, 19:42

BrianV70 wrote: ↑02 Mar 2018, 16:13Is there any kind of flap or check valve where the filler neck enters the tank?

There is a flap/check valve where the fill tube enters the tank...at least on my '98.

If your tank pressurizes, then the vent line is obstructed. Perhaps the vent itself is blocked or clogged with old, rotted foam?

Also, yours is an AWD and the gas tank is completely different than a FWD.

BrianV70 · Post by **BrianV70** » 02 Mar 2018, 21:18

Thanks dudes. I will report back when I find some time to look at it.