moochman4life

Sup guys. So, my latest track day event turned out to produce a recurring "problem": After two 20-minute sessions, my gas gauge winds up reading empty or close to it even though, in actuality, my car would have a half-tank or more left. This has happened on all of my previous track days. After a 20-30 minute session, I'd park the car, let it sit, then check it again and the gauge would go back up a little bit. If it sits for a longer period of time (a few hours), it winds up correcting altogether.

However, if there isn't a lot of time between sessions and I have to get back on the track, my car starts sputtering...you know, like it's not getting fuel. Then I'd get done with that session, let it sit for a while (like over lunch or something), and the gauge reading corrects. I take it for a test drive and, yep, sputtering goes away.

Is ripping around the track causing my gas to get "stuck" in one section of my tank? Please tell me if I'm wrong, but does our tank basically have two sections...instead of it being totally flat on the bottom of the tank, the middle goes up and over something underneath? Every time I've had it up on the rack, I've never thought to check this. Funny, but I always think of this stuff while I'm at work...

Has anyone else experienced this? Thanks!

hammeron

yes, you are not alone.

occasionally if my tank is say between 1/4 and 1/2 and i take a corner to fast, the fuel gauge will drop down near empty and i may get the low fuel warning. it then takes awhile for the gauge to return to normal.

i have an upgraded fuel pump (gt500), so i don't think it's a pump related problem. i don't see an easy way to keep it from happening, without modifying the tank and/or pump(s) design.

Simon1

There are two pick ups in the tank. One sould be running dry or near it causing the issue. Put more fuel in your tank.

My car used to do that but I rarely get to corner carve anymore.

Vapour Trails

That's normal, I've had it happen many times, but never with sputtering. The tank is split, with the pass. side emptying first. It's possible fuel from the drivers side is sloshing over to the pass. side, creating a fuel starvation issue.

I would not allow the fuel to ever get below 1/2 on the track!!!

FI combined with fuel slosh and you could have a lean condition and a snapped rod pretty fast.

moochman4life

I hear ya, and although this has become my norm (topping off the tank), I shouldn't have to. Especially when trying to keep weight down.

Thanks for the responses, guys. Confirms what I've been thinking.

AZ06GT

Had the same issue when under warranty and took in into the dealership 3 times. They never got it fixed, but I got the impression that there are two fuel level sensors, one for each side of the tank. Normally there is some kind of averaging function that provides you with your fuel level. When the fuel starts sloshing in the tank things get confused and the car indicates low fuel. Problem does not occur when the tank is full.

Never had the sputtering, but the car would hesitate sometimes when I rolled into the throttle. There was a separate TSB related to air bubbles building up on the fuel pickup screen causing a hesitation in the 05-06 Mustangs (corrected in 07+). Dealership was able to fix this by swapping out the part.

moochman4life

Cool, thanks man. That's good info. I'll have to find that TSB.

Import_Slaya

Happens all the time on the track. As others have said, keep the tank at least half full to avoid it. Nice avatar pic, by the way--Summit Point Shenandoah by the looks of it?

BigDinTexas

Could switching from the OEM fuel tank to a fuel cell possibly mounted in the trunk eliminate this problem?

Don

moochman4life

I shouldn't have to keep the tank that full, though. I read something somewhere about a gallon of gas weighing XX lbs or so (I really don't want to do the math lol). I would love to keep the weight down.

However, I'm not trying to replace with a fuel cell, either. My car is a "road trip, DD, street/strip, take it to the track and have as much fun as possible without dedicating it to one specific purpose" kinda car.

I just don't see a middle ground here unless I make a new tank...which I'm not doing.

So, I just have to keep it at 1/2-3/4 at all times while on the track.

Oh, yep, Shenandoah Circuit. Love it. Either I'm going back with TrackDaze in May, or I'm going to see what the National Captial Region SCCA has cooking when they promulgate their schedules. I'm looking into their time trials gig. You?