I have a 2002 Outback sport. I began having hesitation problems about one year ago. The hesitation would only occur after a fuel fill up and last for about 1-2 minutes then gone. Did not occur at idle, only when driving. Now, I've been having the issue at varying fuel levels regardless of fuel fill up or not and the hesitation appears to be worsening. The Knock sensor has just been replaced with no improvement in the hesitation. 

I've suspected the fuel filter, water in the fuel, what else? Any thoughts?

Fuel pump possibly.

replace fuel filter first, see it that helps. If not, then suspect fuel pump as dinky suggests.

Is this a year where the Fuel and Filter is a combo unit?

02 still has the filter under the hood as far as I know.

 

How old are spark plugs and wires? Air filter? PCV valve?

^^^ look for oil in the plug tubes too.

 

might not hurt to try a tank with a bottle of Techron, or maybe SEaFoam too.

I think I recall an emissions equip problem that would fill the charcoal cansiter with gas when filling/driving, which would then cause a too-rich condition.

 

Sound familiar to anyone?

^^^ hmmm, I think I read where there was a weight limit on how much a canister could weigh. maybe find that value and pull the canister and weigh it? Saturated cansiter would weigh a lot more than 'dry' I'd guess.

 

maybe the gas tank's vent valve stuck open would lead to this? Or a malfunctioning Purge valve?

Edited July 22, 201411 yr by 1 Lucky Texan