Fuel Injector

[Nagaj54]

What should the PSI be at the fuel injectors on an 8.1 HO 496 MAG?
I just sent out the injectors and 4 were not spraying good.
Had them cleaned and was told 36 PSI is what they are pushing?
1 was only spraying 7.

 

[hughespat57]

Not sure what numbers your quoting here, I think your mixing pressure and volume.

Fuel rail pressure is set by the fuel pump and the pressure regulator valve. It will be what all injectors on the rail see.
Injectors are tested for spray pattern and flow rate at a specific test pressure and specific cycle rate (usually 100%)
Flow is normally measured in CC or ML

 

[scoflaw]

4 bar system. 42psi

 

[hughespat57]

Delphi 8.1L "Marine" fuel injector. OEM # 881693, 881693002.
Direct Mercury Marine replacement for Delphi Part 25348180 & 25176061.

Specifications:
Coil Resistance: 12.0 Ohms
Static Flow: Rate: 43.5 Psi 38.9 lb/hr / 398cc/min / 4.31 g/s)
Factory fitted: With Viton upper and lower o-rings & Fuel Rail Locks.
Part Numbers: 17113739, 25348180, 25176061 Marine 8.1L, 496 Part Number 881693 Genuine Delphi Parts.

 

[Nagaj54]

So my flow test reads:
45 PSI static flow test - LB/HR
at 45 PSI - all Injectors are between 37.7 and 38.5 PSI
Is this an acceptable flow rate?
Before cleaning they were at 7.0, 20.0, 18, 19, 37, 37.5, 37.2, 37.4.

 

[hughespat57]

They are flowing between 37.7 and 38.5 LB/HR or Pounds of fuel per Hour not PSI
that's a high to low variance of 2.07%, less than 5% is considered acceptable, that's a good number
His test pressure is slightly higher than standard which is the 43.5 psi, no big deal.

as @scoflaw pointed out your boat should be running at about 42 psi, that's the pressure regulator setting.

You had four cylinders running very lean, did you do a compression check just to be sure no other damage was done to the cylinders or valves? If not I would do so at least to have a baseline.

 

[Nagaj54]

Yes, all cylinders 170 and 175.
Thanks for correction on PSI, this is all new to me.