I just swapped out my stock fuel pump, because it was dying, for a Walbro.

Now when I turn the key to the ON position it goes to 38psi and when I start the car it goes upto 45psi and then throughout the day slowly goes down to 42psi or upto 46psi when I'm travelling at a constant speed at even 1200 rpm.

Doesn't matter how much I turn up the pressure on the Accel adjustable fuel pressure regulator it still goes down to 42psi.

Is it a bad regulator?

 

Sometimes initially it will go upto 46psi or so when I turn it up but later it drops to 42psi.

I wouldn't normally care but my O2 sensor voltage at WOT is about 854mV. Normally its around 895mV.

 

Anyone?

 

sorry i dont know the answer.........but i would just try changing out the least expensive part first...........its either gotta be the regulator, or the pump, since that is the part that has been changed.

 

Well I just swapped out the pump so I guess its the regulator.

 

could be..........but its always possible you got a bad pump too............im not sure if that would cause the problem though.

 

Is the regulator leaking, pull vac to make sure nothing is coming from there. I assume fuel filter is clean or new! Regulator is only a 5min(4bolts and take fuel rails off) swap and around 50 bucks, make sure to only use DELCO! Aftermarkets regs are worthless and poorly built.