Fuel starvation, can't fill tank to FULL?
 

I was getting what seems like fuel starvation at Thompson Speedway (CT) today. Starting with a full tank, I went out and after 5 good laps I started losing power. Back off for a bit and full power would return but hammer it for a few corners and it'd fall flat again. Feels like fuel starvation I've had before, but with a nearly full tank! I topped it off (2 gallons), went out again and same thing, falls flat after 4-5 laps. Topped it off again, another 2 gallons. This time I noticed the fuel gauge wasn't all the way up to above the "FULL" mark, but a bit below it, call it 7/8 to 15/16 indicated. Not normal for a fully topped-off tank, hmmm.... Took my student out and got the fuel starvation a bit sooner, 3-4 laps in. Brought it in, tried topping it off all the way to the fuel cap, but could only add 1 gallon this time, with the fuel gauge now indicating just below 7/8. WTF...

Backstory:
I got fuel starvation at NHMS a couple of events ago, coming out of 6 and 7 (extended banked left-hander), at 7/8-tank indicated. Could top it off after every session and it wasn't a problem. After that event I got the Verus fuel door and installed it in the drivers-side fuel tank/basket. The install went smoothly, no probs. Fuel door pins engaged the housing perfectly, and I feel certain I reattached the fuel lines correctly.
Next event was Palmer (MA), clockwise configuration. In this config Turn9 is an extended banked left-hander. I got exactly the same fuel-starvation issues I'd had at NHMS, at the same fuel level of 7/8 indicated. Again I could top off between sessions and it was no problem.

Today, it was a bit different as the fuel starvation seemed like it could happen anywhere, including midway through a right-hander after a long straightaway. And it's happening only a handful of laps in. *And* I can't seem to top off the fuel tank.

I suppose I'll inspect the drivers-side fuel lines and basket to make sure I didn't screw anything up, or see if the fuel door has somehow freed itself and is causing mayhem.

Anyway, DAMN! Ideas?

Are you running a stock pump?

Are you running E-85 or Flex-fuel?

Are you monitoring your fuel pressure?

Have you tried replacing your fuel filter or even the fuel pump?

Yes, stock pump. 93-pump fuel. Not monitoring pressure but may try to log data tomorrow. Haven't tried replacing anything.

Most likely will open up the driver side fuel tank tomorrow to inspect and maybe top that side off with fuel. I just tried filling it up again after 35 mile trip home and it took 1.5 gallons, but gauge reads below 3/4 now...

Not being able to fill all the way could be a collapsing fuel inlet line, I thought that problem went away by the 14 cars but it's possible it returned.

If I calculate fuel expended and refill gallons, it seems like I *should* have a full tank.
Arrived at track with full tank. Track miles: ~16 laps (over 3 stints) * 1.7 miles/lap = 27 miles, / 6mpg = 4.5 gal. I added 2 + 2 + 1 gallons at the track, 5 gallons.
Trip home, 36 miles, figure 27mpg, 1.33 gallons, and I just added 1.5.
So it seems like the tanks *should* be completely full, but the gauge keeps reading lower and lower... Currently just below 3/4 indicated.

Is that a fixable thing by a moron at a racetrack with a lot of friends with tools?

Probably not advisable, reaching up past the fender liner of the right rear, if you get halfway and get stuck you might be SOL. If you fill slowly you should be able to top it off to full instead of the fuel getting choked by the collapsing fill line causing the pump to shut off prematurely.

There's a diy/tsb floating around here somewhere.

Yeah, starting with monitoring the fuel pressure would be a good idea.

If you've run your pump dry, in the past, that could have been the beginning of your problem. Fuel pumps use the fuel as a lubricant and to cool themselves.

Wouldn't be a bad idea to purchase a new pump to have as a spare......just in case.

If I remember correctly, that TSB covered just the first few months of the first model year. The problem was remedied with a newer filler neck material shortly afterwards.

Can you hammer it in a straight line and have any problems?

Sent from my GM1915 using Tapatalk

This morning I went to pull the basket from the driver-side fuel tank. Forgot to pull the fuel pump fuse so got a bit of fuel spray! Fortunately contained within the metal underseat area, nothing got on interior bits. Lotsa fuel vapor inhalation... Unscrewed the big plastic collar, tried to pull the basket but immediately fuel fricking POURED from all around the perimeter. Lotsa fuel, still contained in the underseat metal area. More vapors inhaled... Gave up and put it back together. The good news is that the fuel gauge went from sub-3/4-tank indicated to FULL, which by my calcs it shoulda been. Jostling the basket a bit apparently freed the level gauge up and now it works fine. I'll have to run the tank to empty to investigate further. Have to suspect recent installation of Verus fuel door, which went very smooovely but I have to wonder if it mighta busted loose from its pivot points. FWIW the part I got was a 3-D printed plastic thing and NOT the aluminum part with steel(?) pin shown on the website here: https://www.verus-engineering.com/sh...-wrx-387#attr=.

After breathing normal air for a while, took 'er out for one practice session before TT. Got fuel starvation again after ~4-5 laps. Same as yestiddy. TT is 3 laps so no prob there but damn...

The good (GREAT!) news is I went way faster in the TT than in any practice session. Expected P3 with a high 1:23, but won my class with a 1:22.2 vs. 1:22.6x 2nd and 3rd places. Hellzyeh!

Did open track, again got fuel starvation after ~5 laps. Unlike at NHMS and Palmer, where it happened after extended >180 degree banked lefts, I seemed to be getting it most often halfway through the T1-T2 *right*-hand corners at Thompson Speedway, after a long straightaway! Very very weird...

I'd love to hear any theories about wat dafuq is happening, and solutions that don't involve replacing the stock tank with a fuel cell. TIA!

I think next step is to upgrade the fuel pump unit.

Sent from my GM1915 using Tapatalk

Have you begun monitoring your fuel pressure yet? Are you absolutely sure your engine is actually starving for fuel or could it possibly be something else?

Surge tank is the next step. I don't think the fuel basket holds enough fuel for long sustained corners to keep the car feed. I am still getting fuel cut too with the verus fuel door. I need to keep at least 1/4 tank in my car.