hey guys i have a walbro 255 pump in my s4 TII and i think im having problems with it but its only 6 months old....it seems as if it only wants to pump sometimes and other times it wont start and even when it does start the car runs lean under boost like its not pumping enough fuel....so my ? is could this pump be shot already? could i have gotten a bad pump?has anyone else had one go out on them?

 

Check your pump voltage first, and then output pressure (while driving) if you think it's the pump.

 

i checked the voltage at idle and it was a 9 volts....i dunno what else it could be besides the pump..i have a new fuel filter new injectors...i know its not getting fuel when it doesnt start cause i can try starting it for like 5 min and no smell of gas and i pulled a plug and it was bone dry

 

Try jumping out the fuel pump test connector (green connector by AFM). With it jumped out the pump should run continuous with the key on.

DON`T go into boost until this problem is fixed or you`ll be buying a motor.

 

i only have a piggy back SAFC 2 for now and i took and cranked the fuel up to plus 30 and it still ran lean... so im thinking its gotta be the fuel pump

 

has anyone had one go out on them?

 

ok well i guess ill just buy a new one and eliminate the chance that it is the pump

 

dont jump to such fast conclusion.

you say you tested the voltage at the pump and it was 9v at idol. obviosly you cant check it while your driving, unless you have your mate sitting in the boot.
It sounds like your not switching to 12v which can mean a number of things
try cleaning up the earth on your fuel pump and also try the rewiring trick.

 

I had a walbro in TII did not like it at all. The car ran perfect on the stock pump, no fluctation on the narrow band display I was using at the time. So I droped in the walbro and tested the car on 7 psi, the same amount I was running before on the stock pump. This time I would see dips on the display around 5,500 rpm not good. So I decided to rewired the pump as the write up instructs, got 12 volts much better, still didn't see improvements past 5,500 rpm.

Long story short, I never pushed the car past the dip I always got off the gas before hand. But the damage was done, and shortly after dropped a seal trashed my new motor and freshly rebuilt turbo. I also noticed the blip at 3,800 rpm was alot worse, and I'll bet thats where most of the damaged occurred.

 

The narrowband will not tell you anything about this situation. In fact, it may even tend to read lean when it is too rich...

Anyway, in order to diagnose a pump you must first eliminate any other problems. It's likely that you need to do it anyway, so do the fuel pump rewire. If you still have pump issues even with fresh wiring, then it's most likely a bad pump.