OX66 250 Question

[Skatermike24]

I have a 2001 ox66, at around 3500 rpm it seems to surge, only happens at this rpm, lower or higher , everything is fine. When it surges it will surge a few hundred rpm's, changed everything I can think of pumps filters etc, dont think its a fuel problem cause it run perfect at a higher rpm....any idea's

[Tucker]

Have you tested the 02 sensor skater?? Ever clean it?? Need the harness and the boat needs to be running between 3000 & 4000 RPM. Voltage should be .3 volts. You checked HP fuel pump pressure right?

[Skatermike24]

I cleaned the 02 sensor end of last year. Have not yet checked fuel rail pressure, is there a easy way to do this?????

[Tucker]

Gauge kit from Harbor Freight.

[Tucker]

Also, make sure you get the right size fitting to fit the schrader valve. I have 2-gauges with fittings that are too big.

[Skatermike24]

Can someone tell me the proper pressure to look for... do I need to run the boat or is idle fine.

[rodbolt17]

all testing MUST be done at the PROBLEM rpm and load.
rail pressure must stay at about 35 PSI.
much more and its rich,much less and its lean.