Fuel tank filler leak

[Packer fan]

In the past I noticed that when I filled the gas up all the way I could smell gas in the garage. I didn’t see any fuel on the floor. Fast foreword to this last week when the roads were salt free and I went for a ride. Wow was that fun, you forget what it was like after a long winter. I did a counter clockwise donut and on the second time around I saw a line of fuel on the ground. When I came home I discovered that the pinch weld below where the filler neck goes into the tank through the grommet was covered with fuel. My questions are. Does the filler neck go all the way in so the bead rests against the grommet? Mine doesn’t. And mine is on a bit of a angle going through the grommet in order for it to attach to the fuel cap flange. I guess it may have also leaked from where the filler neck goes into the rubber hose. I noticed that the clamp was not all they way at the top of the hose where the hose clamp wasn’t at the very top so when looking in from the gas cap there is a gap until the clamp location.

Thanks

[frankeeski]

You need a new one of these, the seal dries out and then leaks. Remember to lubricate the inside of the seal before install. Petroleum jelly works best.

https://www.rockauto.com/en/moreinfo...134133&jsn=465

[michael everson]

The bead does not need to be all the way in. Its actually there to keep the pipe from coming out if you used the keeper bracket that FFR supplies.
Mike

[Packer fan]

Thanks

[mike223]

I did a counter clockwise donut and on the second time around I saw a line of fuel on the ground. When I came home I discovered that the pinch weld below where the filler neck goes into the tank through the grommet was covered with fuel.

Every one of these cars (including mine) that I have seen autocrossed hard spewed fuel from the vent hose as soon as they were put in a long left hand turn with the appropriate level of enthusiasm.

The fix for that problem is the vent hose needs to come up about a foot toward one side of the car or the other (typically it comes up toward the passenger side with the Mustang tank in the roadster), then it needs to drain toward the opposite side of the car.

The object is to route the vent line toward one side of the car until it is near vertical, "U" toward the other side of the car then drain toward the other side.

That way when the fuel crowds to the vent side of the tank it just fills the vertical tube (to the "U") and has no further to go.

When the g-force subsides - it drains back into the tank.


Instead of just spewing out the vent line for the duration of the corner (or doughnut).


I've seen people try various check valve upgrades - but none of the (pricey) check valves close fast enough to prevent this effect in autocross, in my experience.

We always ended up rerouting the vent line as (roughly) pictured below (pictured looking at the back of the car).

That always cured the problem.

I'm not certain you have the same problem - but you might.


Vent.jpg



P.S. - Anyone who finds this problem is well advised to get a good road racing oil pan - complete with extra capacity, wings, baffles, trap doors - the works.

Because your oil is running up the side of the engine the same way your fuel is running up the vent line - except it's happening in both left + right hand corners.

Oil starvation follows - nothing good comes from that.


Yes - I had to replace bearings, polish the crank, and install a RR pan too - and considered myself lucky to figure it out before it became a catastrophic failure.


Good luck - words to the wise.

[Packer fan]

Every one of these cars (including mine) that I have seen autocrossed hard spewed fuel from the vent hose as soon as they were put in a long left hand turn with the appropriate level of enthusiasm.

The fix for that problem is the vent hose needs to come up about a foot toward one side of the car or the other (typically it comes up toward the passenger side with the Mustang tank in the roadster), then it needs to drain toward the opposite side of the car.

The object is to route the vent line toward one side of the car until it is near vertical, "U" toward the other side of the car then drain toward the other side.

That way when the fuel crowds to the vent side of the tank it just fills the vertical tube (to the "U") and has no further to go.

When the g-force subsides - it drains back into the tank.


Instead of just spewing out the vent line for the duration of the corner (or doughnut).


I've seen people try various check valve upgrades - but none of the (pricey) check valves close fast enough to prevent this effect in autocross, in my experience.

We always ended up rerouting the vent line as (roughly) pictured below (pictured looking at the back of the car).

That always cured the problem.

I'm not certain you have the same problem - but you might.


Vent.jpg



P.S. - Anyone who finds this problem is well advised to get a good road racing oil pan - complete with extra capacity, wings, baffles, trap doors - the works.

Because your oil is running up the side of the engine the same way your fuel is running up the vent line - except it's happening in both left + right hand corners.

Oil starvation follows - nothing good comes from that.


Yes - I had to replace bearings, polish the crank, and install a RR pan too - and considered myself lucky to figure it out before it became a catastrophic failure.


Good luck - words to the wise.

Thanks
I have a moroso oil pan with the hinged flaps/ baffles and a little extra volume. I will be looking at my vent line also. It does go up a ways. This one was definitely coming from the filler side.

[Packer fan]

I think I found the culprit.
I used a little fuel lube this time.20210402_102841.jpg