MK1 Mazdaspeed3 hesitant to boost/rev

[wmp]

Hi guys I have a MK1 Mazdaspeed3 at the moment , and I've noticed a weird problem on mine.When I seem to go below half tank on mine the car seems to really struggle to boost cleanly and feels very sluggish.

I can hear a slight whine or whirr below 1/2 tank in the cabin but it's hard to figure out where it's coming from.Filling up and letting the car stand for an hour or so / resetting the ecu seems to bring back normal driveability.

Could bad gas be the problem ? I've filled up at least 5 times now.My cars been in twice , and booked out by Mazda as having no problem.

Anybody perhaps have any tips / suggestions what it could be ?
Any help would be appreciated.

*Sorry if this is in the incorrect section to post in*

 

[Huligan]

I suggest you take it to the dealer.

 

[Darth Vader]

How helpful, Huligan, he says he's done that twice. I'd suggest getting a Dashhawk or something that can measure DI fuel pressure. The in-tank's pretty good for a stock part, it's usually the DI pump that is crap. However, your report of weakness when 1/2 full suggests a plugged filter or a failing in-tank, since the fuel level affects performance. Why that reasons out is the in-tank primes the DI pump and high fuel level helps by adding the force of gravity to the tank feed. Plus, fuel is used to cool the in tank and as it gets low, it can't do that. That's why you should never run an EFI car on low fuel for long periods.

 

[JamesCH]

Before you go replacing fuel pumps make sure it's not something silly, try throwing in some dry-gas to make sure it's not a moisture build-up problem. Having said that, if a fuel pump is failing and it runs super-lean you could toast your motor...