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MikesCoupeGT · Joined: 18 Oct 2006 Posts: 474 Location: Ontario Canada

At the end of last season I noticed that when the car was between 1/2 and empty, call it about 3/8ths and below in the gas tank, I would get a fuel starvation coming out of the the corners. The car would stumble. I still need to pull the tank and get the top quarter fixed to stop it from leaking, but I want to know if there is a way to correct this with a Fuel injector cleaner or something?

Any response is good. Thank you.
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Cheers;
MikesCoupeGT
'76 924
'83 944
''19 Elantra GT N-Line

Fifty50Plus · Posted: Fri Apr 03, 2015 5:15 am Post subject:

It's not a fuel injector problem.

The right side of the tank (looking from the rear of the car) is much deeper than the left side. The fuel pickup is on the bottom right side of the tank. When you are in a high speed right hand turn with minimal fuel on board, the fuel sloshes to the left side of the tank and away from the pickup. Shortly, you have pump cavitation and loss of fuel pressure to the injectors until you straighten out and the fuel sloshed back down to the pick up.
On my race car I've found that by starting a 45 mile race with at least 3/4 tank of fuel it doesn't cavitate. One half tank is iffy and it might starve a bit on the last couple laps.
There is no way to baffle the stock tank for this fuel slosh. I'm thinking of replacing the stock tank with a fuel cell.
BOL
Chuck
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1979 924 NA race car H-Prod SCCA
1982 924 NA race car - Sold
1981 924 Turbo sold
1982 924 Turbo sold
1972 911 E race car - traded for Cayenne Diesel
1975 914 1.8 Building for H-Prod SCCA

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

FWIW, the late plastic tanks don't seem to suffer from this. . .I can run my race car near dry with no sputtering, and we have a semi long third gear right hand complex at Portland.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

924RACR · Posted: Fri Apr 03, 2015 9:31 pm Post subject:

We have no problems running the #77 down to 3/8-1/4 tank. I won't risk it below that.

I'd be investigating your pickup, removing and making sure it's clean... maybe also review your plumbing from that to the pump...

Oh, I suppose one additional thing is, are you sure your gauges read properly? Full when full, empty when empty?

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

MikesCoupeGT · Joined: 18 Oct 2006 Posts: 474 Location: Ontario Canada

Thank you for all the replies.

I would go the plastic tank route if I was going to continue to track the car. This may be its last year for Watkins Glen, if I cannot source a good Fuel pump at a good price for the 944.

Otherwise to answer the questions. Sometimes the fuel gauge is sketchy below 1/2 tank in its reading, but if I am just cruising then I don't have the pickup issue.

If getting to the in tank pickup was somewhat easy i would be looking and cleaning that as well. I probably will look into it soon. I have to lift the car up anyway to replace the brake master cyl with the one I rebuilt which means a bleed of all the brakes. That might be the best time to do that.

Cheers;
_________________
Cheers;
MikesCoupeGT
'76 924
'83 944
''19 Elantra GT N-Line