Anti-Slosh Fuel Tank Mod

GTEASER

Posted February 19, 2015

- Share

Posted February 19, 2015

I am having a fuel starvation condition in my '92 SS that is a direct result of fuel slosh because of insufficient baffling in the OEM fuel tank. It only happens when cornering hard on right hand corners or highway clover leaf on-ramps/off-ramps and when the tank is about 1/2 full or less. This happens regardless of the fuel pump being used. The lack of fuel at the pickup for the period when the fuel sloshes causes the pump to cavitate and create an air bubble (kind of an aneurysm) in the fuel line which translates to a rapid reduction in injector pressure for just a few seconds. And if it happens often, especially on turbocharged motors, this condition could cook a motor as a result of this lean condition.

I did a little research as a result of a Facebook post in the 1st/2nd Gen Legacy Owners group and it turns out all the Impreza guys (1993-2007) are having this issue too, to varying degrees based on year and model. The STi's came with a "Box" on the fuel pickup sock in the tank to combat this condition, but the STi part is very expensive. The STi box looks like this.

A solution is a full-on surge tank setup, but this can be very expensive and requires a second pump. One company that offers a good one is Radium.

http://www.radiumauto.com/Standard-Fuel-Surge-Tanks-P515.aspx

On www.RS25.com I found another solution that only costs about $10-$50 depending on how far you want to take the mod. It uses a small 24-32oz R/C airplane fuel tank to create a box around the fuel sock that mimics the OEM STi unit. You can keep it simple by putting the "box" around the fuel pickup sock and redirect the return line/jet pump directly into the box, or go all out and remove the jet pump altogether, add an inline pump from the drivers side fuel tank pickup and direct both that and the return line into the box. Guys have gotten it work just fine both ways.