2001 250hp yami ox66

[contender]

I have gone thru a lot of the threads about the problem I am having with one of my engines. The engine starts right up and idles fine. It will not do more than 3500 rpms. It does not surge or cut out. The engine has about 200hrs on it. So far I have done the following:

Cleaned vst tank. Not dirty
Changed plugs. Fouled
Changed fuel filter on engine.
Changed water seperators.
Cleaned o2 sensor. Not to much carbon buildup.
Decarbed with Sea foam.
Primer bulb does not collasp.

I have read that it could be one of the fuel pumps. Is there a way to test these before I start changing them or is there something else I should look into? Thanks for any info

[boats.net]

If a fuel pump is bad then the engine run worse if you pump primer bulb, you can take pumps loose from block and see if gas comes out hole in back when pump bulb.

[contender]

When the motor is running I did pump the primer bulb and nothing changed. What else could cause loss of rpms?

[jb123]

try running it with an auxillary tank hose and ball to rule out a supply side issue.
the vst filter should be cleaned regularly and 02 sensor should be also checked/tested.

[contender]

I have twin motors and I switched the supply line from the other side and it does the same thing.

[bonafishark]

I have the same engine-different troubles. I download the SELOC service manual online and there are a number of tests you can perform on the fuel pumps and also EFI.

try: http://www.selocmarine.com

[contender]

Thanks for the info. I had similiar problems like you are having on my other engine last year. It was the vst filter. I cleaned it and never had the problem again. There are so many things that can go wrong it's hard to figure it out.

[bonafishark]

Funny- I got yelled at by the marina owner today-telling me I was not allowed to work on the boat- wanted to charge me $400 to clean that VST filter. No kidding. Drunk fool.

Anyway, I cleaned the filter, put back together with new gasket, heard the HP pump come on and she started right up. Let her idle for 20 mins, shut her down, tried to start again and no go. Did not hear the HP pump come back on.

I am guessing the HP pump is bad but am curious as to whether that pump would work intermintanntly if bad or not at all.