How would i know if my fuel pump is having problems??? I just recently started running lean, and I have no idea why?! I just recently replaced my o2 sensor w/ a brand new bosch one and it still hasn't changed. Someone mentioned to me that it might be my fuel pump-- I have a walbro 255

 

do you have bucking problems with the car not having enough problems . Is the timing on-point? check your plugs and your wires ,fuel filter may be bad . If your reading it from of the a/f ratio guage then your wrong cuase its just a light show unless you have a wideband o2 sensor. and last but not least check the fuel pump relay.

 

the car doesn't buck at all, it kind of stutters every now and then around the 2.5k to 3kish area--- I haven't touched my timing, but i'll check it. Plugs are brk 7e's, wires are decently new. Haven't changed the fuel filter yet, and i've got about 67k on the car. I don't have an a/f guage for the same reason that you've said. The fuel pump is on, because I can hear the whining of it. But where is the pump relay at? Also, when I check the plugs they always look brand new, w/ some signs of lean-ness on them.