Originally Posted by FabFlatFour
Ahh...I didn't realize that there is a jet pump that transfers fuel from a sub-compartment. Depending on how the jet pump is arranged if the fuel sloshed in the tank it may cause a vapor pocket and choke the actual fuel pump causing the car to die as Kean mentions above. Hmm interesting...I think this is device is kind of like an "ejector"...it would make sense as the return fuel from the engine would be like the motive fluid flow and the fuel from the tank would be the entrained fluid flow.
I wonder why the tank would be set up like this...perhaps to reduce sloshing that a single compartment tank could possibly have?
I should add that what I wrote is definitely true for my 02 wrx. I cannot say for sure that it is that way for all Impreza models and years post 2002. My first mod was a full set of Service Manuals for the first year wrx in the USA, figuring that even the dealerships were not up to speed yet on the car.
There's lots of nice grease and dirt on some of those volumes now.