Tchleung

My setup is: Walbro 255LPH HP fuel pump with a B&M fuel pressure regulator.

I noticed today via B&M fuel pressure guage on my fuel filter, that at idle, if it's at 40PSI, and I gas it, the fuel pressures DROP to like 36 or so! WTH. It's supposed to go the other way in 0 Vacuum. So I unhooked the vacuum, and it red about 45PSI, blocked the holw with my finger on the vacuum line to the intake manifold to hold it at 45psi and keep idle the same. I then gassed it via throttle rotor and the pressures still dropepd teh same amontu roughly. WTF, failing fuel pump? But how can that be. I isntalled that and have only ran it for maybe 3 weeks tops. So I am thinking maybe it's the fuel pressure regulator, as I know how bad the B&M's are. So I replace it with a stocker, and it does the same thing. Fuel pressures drop. I'm boggled so I put the B&M back in and decide to jack the pressures to 45PSI idle and 50psi idle with vacuum line off. I test it again, and waht do you know, ti works correctly now and goes up like it is supposed to?!?! I then proceeded to do soem testing and have found out that anything in the low 40's PSI with vacuum on it, the pressures drop, but anything about 45+psi, the pressurse RISE?!?! so I don't think it's my FPR since my stocker did the same thing essentially. Now from my understanding, if a fuel pump is going, it CANNOT keep up with fuel pressure therefore droppngi in fuel pressure at all times under load. So that's why I'm 50/50 that it can and can't be the pump as it is fine anything over 45 or so PSI at idle. I've also changed my fuel filter, the last things are now is to repalce my "NEW" fuel pump, and tomrorow I'm gonig to try another fuel pressure guage to make sure the B&M isn't taking a **** either. Any ideas would be helpful. TIA.

Tchleung

TTT

Tchleung

Bump

gotboost95

Its that ragulator had the same problem. When I put my turbo on
it ran ok for a month then i noticed it running lean at full throttle
so I look at my fuel pressure gauge was ok but when I would tap
the throttle the pressure would drop from 45 down to 38.

93lsd

yeah sounds like your fuel pressure reg may be bad try a stock one and see if it drops down under wot.

Tchleung

In my first post I already stated that I swapped it uot for a stock one and it did the same thing sicne idle pressure was like 38 or something