2001 yamaha 150 ox 66 loses power for couple of seconds

[moseslake1]

Help would be appreciated, original owner 2001 150 trp, every once and a while at plane engine will cut back for a couple of seconds and then return to original set power. It seems to be happening more frequently. I will check the fuel filters, but I change them regularly. Any Ideas, Thanks

[lswjth3@yahoo.com]

You may want to start with replacing the oxygen sensor, I put the NGK equivalent on mine $38 vs $300 for the Yamaha, do the seafoam decarbing procedure, replace the plugs and see what happens next.

If this does not fix it then I would move into the 3 LP pumps on the side, the VST filter, Fuel regulator filter, primer bulb and water sep filter. hope this helps, good luck!

[jfbetz01]

Sounds to me like a clogged VST filter. When was the last time this filter was changed? Dirty 02 sensor will usually show up as a steady decrease in performance/fuel economy, not necessarily periodic sputters. When VST is clogged, it is often when you move into higher speed/RPM's, at a full throttle start, or when you hit waves while on plane.

[99yam40]

before throwing parts at it I would monitor fuel pressures when problem shows up.
may not be easy if it does not happen often.

just eliminate what you can with testing before buying parts

I am sure there are things to be check with proper test equipment

[jfbetz01]

Checking the VST filter will not cost anything, except maybe a replacement O-ring gasket. Once you separate the lower vessel from the upper, you can inspect the VST filter. It will not be difficult to see if there is build-up on the screen; the filter looks like the one in the pic. If there is significant build-up, this is likely your problem. and I would check the fuel in the VST for excessive water content. The glass on the right came out of my detonated OX66 250 VST tank.

If all is good, you will need to replace the filter and o-ring gasket. Trying to re-use the gasket is problematic...it seems to expand when it comes off and is difficult to get it to stay in the groove it came out of. Some people say putting it in ice water to shrink it a bit helps...but replacing would be best.