2000 Yamaha vmax 225 issues

[Jburton1008]

About 4 months ago I noticed that it was starting to bogg down on take off. I changed the LP pumps, plugs, fuel filters and the VST filter. Did not see the results that's I was expecting. About 2 months ago the motor started to cut out while running on plane and was still having the bogging down on take off. Tested the HP pump inside the VST tank and found that it was working intermittently. Replaced it and it is now not cutting out while on plane. But still has the bogging issue and running very rough. This past weekend while at the Skeeter owners tourney they had the Yamaha guys there working on motors at no cost (very cool I thought) but anyways I took it by their booth and they started looking it over and everything was checking out fine until they put a pressure gauge on the VST tank. It was pegging out his gauge. He said it should be at 35psi and it was getting over 100psi. I have a new pressure regulator on the way but is there anything else that you would check or do you think that this may be the problem. I do know that it is running very rich due to having an overload of fuel being dumped in the engine. But was just wanting to hear from anyone and what you think.

Thanks. Jonathan

[rodbolt17]

your going to have a spare regulator.
why did they not simply remove the regulator,remove the filter behind the regulator and clean it ??

but hey
that's just me.

[Jburton1008]

The guy that was looking at said something about not being able to get if off from the top of the VST tank top. Is the a special tool that is required to remove it. Would the screen being clogged up not allow the fuel to enter the motor and cause the excessive pressure.

[rodbolt17]

first thing ya gotta do is understand how the system works.

from the HP pump it goes to the rail.
to maintain an even rail pressure ,even when injectors are fireing, you have to have a regulator.
fuel returning from the rail to the VST goes trough this regulator.
for some reason Yamaha put a filter in the return path after the regulator and before the VST .

if it clogs rail pressure increases.

the ECU does not know you increased rail pressure .
same injector "on" time with double the pressure means double the fuel.

once you get the rail pressure correct go clean AND TEST the O2 sensor.

no special tools needed to access that filter.