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Mercury 225 Optimax lost rpms

T

tamungons

New member
Motor is running about 10 percent less than usual rpms. It did sit without going out for almost two months. Had close to full tank of gas 87 Octane. Could the gas have lost some octane during that sit time? And, would that cause the loss of rpms I am experiencing. Seems to sound ok running just not quite getting up to the usual 5500 rpms it tops at about 4900. Should I drain tank and try some 93 octane? I've changed p[lugs but that didn't have any response.

Thanks,

Tom
 
The old gas could have phase separated a bit (leached out some moisture).

I would start with fresh gas (and I would really get rid of all the old gas), you don't need to go to 93, but a mid-grade wouldn't hurt (89 would be fine).

If that doesn't bring it back all the way I would change the filter at the VST. It might be loaded up with water/crud.

Unstablized gas gets old in about 2 weeks. Always run stablizer and seal the tank when not in use (so for a built in tank that means covering the vent on the side of the hull)..
 
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