i have a 1997 sti v3
mods are: simtek ecu,fmic,740 injectors,unequal headers and full exhaust 3inch,induction and few other bits

when i had it mapped from simon he told me fuel pump wasnt a walbro and i would need to change it soon (it always had a whine on ignition and idle and was told its not normal for a constant whine from pump)
i got the walbro 255 fitted last week and when the old one came out that too was a walbro 255 lol,however since fitting the new one there is no constant whine and have a issue with the car...
it seems to have a fuel cut issue or a misfire,i have to rev it hard to pull off when its warm otherwise it wont pick revs up and feels like its cutting out,
could this be that its running very lean or rich due to a new fuel pump?
i dont want to adjust the FPR as it might mess the map
it boost fine after 3.5k rpm without any cuts
also it had a issue of spluttering/jerking before i changed the fuel pump and when i changed the plugs and coils it stopped...however got alot worse when i changed the pump..

i have added a short vid that might help what im on about as my explanation might not be clever enough lol



any advice or help would be highly appreciated
zak

 

Have yot tried putting the old pump back on and see if that cures it

 

no i havnt done that,i would have thought it wasnt fuelling right as the old fuel pump was set to high flow fuel pressure and the new one isnt...however its a direct replacement so therfore it shouldnt make a difference...unless the old pump was knackered??? if that makes sense lol

 

It rather sounds as if your mapper needs to look at your car again. Get Simon's views as he has first hand experience of your vehicle.

 

You will need the new fuel pump to produce as much pressure as the old one, and definitely more than the pressure setting on the fuel pressure regulator... 3.2 bar to 3.4 bar at a guess with vac line removed from FPR when measuring.

If the new fuel pump is giving less pressure then fuelling will be off, if less pressure than FPR set for then I guess weak mixtures, certainly off the map.

Read the gauge on the FPR - or put one on the FPR or in line and check the fuel pressure.

 

i would say you need to get straight back on to simon as your car needs re mapping by the sounds of it . it could be your old pump was fooked and now the new one is pushing too much fuel through but then again it could be something that isnt to do with the pump but simon will tell you more

 

thats what im hoping,im planning on putting a bigger turbo on and getting simon to come out and tweak the map,i forgot to mention it happens only when its upto optimum temp

 

sounds as though its overfueling when have you had any problems with the lamba.
my sti was giving me problems when warm esp when moving away at normal speed when warm but ok when cold and that was my front lamba.

 

i thinks thanks cause the front lamba sensor is an air/fuel mixture sensor