Car Running Ruff After, Replacement Of Fuel Pump

[4drftn]

hi, i recently replaced my walbro (255 LPH) fuel pump with the same walbro fuel pump (255 LPH) in my r33 (rb25det) and my car is running a little ruff, at idle it would bounce from 800 rpm to 1100, when starting sometimes it would stall or nearly stall, and of a morning (when it is cold) it will idle anywhere between 1500 rpm - 2000 rpm!... replacing the same fuel pump shouldnt change a thing so i thought. and yes the part no. is the same (GSS342).

what could it be? any suggestions or info will be great.

cheers 4drftn

[jeffworld2]

try changing the fuel filter, its in the engine bay near the plenum and costs about 30-40 bucks from nissan.

If thats not it, unfortunately you will have to open the fuel tank and have a squiz. similar thing happened to me, where the bosch 040 was installed with a hose that got eaten by the petrol and so the pressure was not getting through 100%. (despite the repco guy telling me it was submersible efi hose- bastard)

what ecu is that on? if not stock perhaps the low rev light load maps need looking at

[4drftn]

yeah i replaced my fuel filter going back about 2 months ago... would the fuel get eaten away that quick? i know the piece of hose between the pump and the bottom part of the bracket might not as it was a bit of left over hose from when i changed my fuel filter... might have to look at that... not looking forwards to taking it back out though

my ecu is a microtech LT-8 which controls my fuel and ignition so could be it... sadly i dont have a hand set, but i should be able to take it to a performance place to get it checked out.