What's with all the fuel leaks at Gingerman? (Page 1 of 2)

After checking the evac lines, fuel lines and tank, we surmised we had an issue with the filler tube. Massive amounts of silicon and metal tape were applied in a fruitless effort to stem back the leak.

Such a disappointment as we were sure we were just minutes from blowing that engine to kingdom come!!

We had a working theory on the way home. 

We know that our cap and basically our entire fuel system was sealed shut and airtight - early in the race we heated and pressurized our tank.  It vented for over 30 seconds when we took the cap off. 

Vented caps vent at some small pressure (1-2PSI).  That's big if you are talking about air pressure - but less when you are talking about fluid pressure.  You can get 2 PSI under about 4' of static liquid.  Add dynamic pressure of sloshing and some static in-tank pressure and you will get the cap to vent gas under a few inches of movement.  Add all those long right hand turns and you get fuel moving dynamically up into the filler neck, slamming into the vented cap, and then coming out through cap vents. 

That is our working theory because once we worked out our tank vent issue and moved our exhaust away from the tank, we were still trailered with a gas leak. 

Of course, the second part of this is that the starter was along the front straight just after a hard right hand turn and was in prime position to catch any spillage that occured - unlike CMP where the flag stations are all on the inside of the right hand turns and generally don't have a good view of fuel leaks.

Rob, I'd second all that. I raced a brand new Mustang in SSGT some years ago, and it leaked too when you corner fast enough (Mid-Ohio).... Not sure we can totally avoid that without a fuel cell at some tracks. We got bounced, and not sure we can fix it short of a fuel cell. Maybe an add-on trap door?

Several of the leakers had fuel cells. The cell is not a cure-all for the leaky-race-car problem.

I've seen fuel leaks at every race I've done and often out of sight of corner workers-- outside of the last turn before the finishing straight at Thuderhill was the most recent spot that comes to mind. And as I mentioned previously, I have always seen a crown vic leaking fuel from it's filler neck-- at every race. Not trying to target them (and it may have been the same team -- but one had no trunk, I recall), but I wonder if there's something inherent in their fuel system/tank that causes it.

Someone suggested to me to wrap the fuel cell vent tube around the cell so that it would actually take a couple of rollovers to cause it to spill out of the vent tube. This is from an offroad guy. Our vent tubes have rollover valves in them, but it still doesn't sound like a bad idea.

I'm interested to hear how the fuel cells leaked fuel so I can check ours for those weaknesses.

Rob, sorry you guys couldn't get that issue closed out, but I sure enjoyed the work on that pseudo crown vic.  Great time hanging out as well!

If it helps you chase the issue, you did have gas spraying out on the 10-11 straight when I came by at around 4pm Sunday.  It was spraying out about 2ft and made for a nice water feature.

I'm still waiting to hear how the debodied Vic did other than the leak factor. Was it glued? Loose? Lap times?

it corners and stops really, really well...better than the MR2, we think.  it's neutral and easily catchable if it gets loose.  the steering sucks, though; i noticed 2-3" of on-center free play.

it is quick enough but not especially fast in a straight line; part of that is the crap diff (really tough to put power down out of corners), part is the auto tranny (lots of hunting for gears), and part is that it sat in a field for two years before we bought it.  Dave set our fast lap at 1:50.8, IIRC.

weird that the MR2 is the "fast" car and the Crown Vic is the "handling" car.  the wing makes a difference; flattening it on the straights raised our top speed 5-7mph.  with it up on the stright, you could see the downforce compressing the rear suspension.

How did you read that into what Rob posted?  They were hundreds of laps down and were not going to risk health and safety to run a car leaking gas.  They were black flagged Saturday from leaking fuel.  I was on the phone and texting with the guys and they thought they had the problem fixed when Sunday started.  Nobody on the STS would knowingly run with a gas leak.  The risks are way too high.  We've probably run a combined 20 car/races in three seasons with no gas issues until now.  We are watching too.

The turbo bird was gasoline tight, fortunately.  As far as water, we had a pinhole weeping in a line to the oil cooler with only a few hours to go.  Brought it in every 20-30 minutes and topped it off.

I talked to the starter after the race, as he was looking closely at the car as it passed for a few laps.  He didn't see anything, so no foul.

We weren't there with our "brake-rotor-shedding-alfa-fuel-tank-opening" Mustang so you can't blame us for the excessive leaks.

Everything that Buzz said... 

I think that the Vic stops better than the MR2 and has better corner entry grip, but the MR2 had better corner exit speeds.  I don't know who set our fast lap - it says lap 6.  Our transponder was mounted incorrectly (first time it didn't work like this and I think that the track wires weren't picking up a lot of cars) so I don't think that we got any of Daves laps.  So it would have been either Mike or Kurt - I don't know who got into the car after we fixed the transponder.