VST filter question 250 OX66

[scjmc]

Hello all. I have been reading on this site for some time, but now I need to ask your advice! I have a 1997 Yam 00x66 250. This weekend it intermittently (did it twice) lost power and the RPMs backed down. If I reduced the throttle, they would come back up. Only shutting off the engine and restarting it solved the problem. From reading on here I want to clean my VST filter. Where is it located? I think there may be trash partially blocking it. Any other suggestions would be appreciated. Thanks!!

 

[PBJohn]

Re: VST filter question 250 OX66

The VST is on the port side of the engine. You will need to remove the phillips screws to seperate the tank. The filter is locked into the bottom of the fuel pump. Also check your low pressure pumps that are mounted on the same side.

 

[scjmc]

Re: VST filter question 250 OX66

Thanks for the info, I will check that filter. Can bad low pressure pumps cause intermittant power loss, or would they be a problem all the time?

 

[scjmc]

Re: VST filter question 250 OX66

Is removing the pump to get at the filter self straight forward, or is there something I should know?

 

[snowmon]

Re: VST filter question 250 OX66

you should really get a yamaha manual. shows proper assembly and disassembly. this is pretty easy stuff. i find it easier to remove mounting bolts to block but leave all fuel/oil lines connected. remove the phillips head screws to seperate top from bottom. you'll find the electronic fuel pump inside the case. the filter assembly is attached to the bottom of the fuel pump and is easy to disassemble. i clean filter by blowing wd40 from inside of filter out as most of the blockage is on the outside. i then blow compressed air to finish and dry the mesh. also if you haven't changed your low pressure pumps do it. these also will cause rpm drops and worse if there is a tear can dump raw fuel into block and hole in block will soon follow. the things you should check as well are o2 sensor, throttle position sensor, all filters including those on the injectors. if your in an area that just switched to e10 fuel this can also create a pile or issues including killing priming bulbs, check valves and clogging filters. good luck

 

[scjmc]

Re: VST filter question 250 OX66

Thanks for the advice. I just bought this boat, and don't know what fuel was used in it before. There are 2 marinas that sell non E10 fuel, and I will be using those. From further reading I agree about the O2 sensor, injector, and regulator filters as well. I looked in the tank with my boroscope and it looks like very old fuel.

 

[scjmc]

Re: VST filter question 250 OX66

Resolved!! Got the VST filter off and it was clogged with very fine particles. I back rinsed the filter and then carefully (92$ filter) blew it out with air. I also noticed fine particles inside the VST tank, so I cleaned it out also. I put everything back together and went on my shakedown run... Went to Marathon key for the boat races (about 70 mile round trip). It weas WINDY I had to power through about 20 miles of 3-5 footers until I could get into the gulf. The motor performed flawlessly. The trip ran 29.1 gallons through the motor with no problems.