Thread: Problems after installing Walbro 255

I installed a Nismo FPR, Hallman proRX manual boost controller, then my walbro fuel pump. I ran my car for a few days just with the FPR installed so i know thats not the problem, The car is hesitating real bad, the fuel lines on top i know arent backwards. But the lines inside im not sure about. My fuel pressure went up since i installed it. If i had the inside lines mixed up would it even run? Maybe to much fuel? Can anyone give me insight on this?

What's your fuel pressure showing right now? What's your setup?

its over 40psi when warm and at idle when before it was at aboue 36psi before the fuel pump install. My setup is

USDM 9.5:1
U12 T25 setup (stock boost) i have had it up to about 9.5psi before.
JWT S4 cams
3inch exhaust
front mount.. etc...etc

are you looking torun 3 or 4 bar with it

i have a 3bar program

when your car is sitting there and idling and you rev the engine up manually with the butterfly from the thorttle body, does the psi fluctuate? or hesitaate that was too?

Turn the fuel pressure back down to 3bar then. with vac line disconnected and capped off it should be 43~44 psi at idle. Sounds to me like it's dumping enough fuel to cause a rough idle from an incomplete burn.

EDIT: Should have mentioned, Walbro 255lph pumps generally push a few PSI more than the standard fuel pumps, given the fuel pressure regulator stays the same.

Meaning, if you had a stock FPR and swapped from OEM to Walbro 255, you'd be seeing anywhere from 3~5 or so PSI more than stock. So just turn your FPR back down to what it needs to be

Rob,

let the car run, pull the fpr vac hose... adjust it to 44-45psi, then reconnect.

if you vacuum is around 18inHg it should drop to 36 with the vac hose connected.

You didn't swap the lines backward at the pump, you would know.

Tekster beat me to it.

GET A WIDEBAND COT DAMMIT!

Yeah it fluctuates.



I kinda figured maybe its dumping to much fuel. Ill adjust it and let you guys know how it goes.



Yeah i think if i reversed the fuel lines id have major issues.

Not really, it just wouldn't run...

if it still hesitates at idle, its your cams... raise your idle a bit if you can... if that isn't it, I would like to know if you have the right tee on the VC hooked up to the intake pipe...

if it hesitates when it hits boost its likely your plug gap...