2002 Yamaha F225 unstable RPM's

[Caribbean Dinghy Dog]

Took the boat for a spin (very windy and choppy seas) and noticed that a few times the starboard engine rpm's were all over the place (up to 4,600, down to 2,300 and so on). As soon as it happened, I put the engine in neutral and then back to the required rpm's to match the port engine and this worked for a while but eventually rpms started jumping all over.

Can you give me some suggestions as to what to check that may be causing this rpms' behavior? FWIW, I had some issues with the throttle cable in this engine, my mechanic made a temporary fix while a new cable arrives.

TIA

[99yam40]

need to watch the temporary fix while problem shows up to see if that is somehow moving the throttle.We have no idea what he did to it

Watch the throttle on motor to see if it is moving or if something else is varying the RPMs

[TownsendsFJR1300]

Plus 1 ^^^.

Do both engines pull fuel from the same tank, fuel / water separator?

Perhaps the additional bouncing around kicked up water in the fuel tank and the engine
responded to "it". Check the under cowl fuel filter (if equipped-transom filter) for any water / crap

Wouldn't hurt to drain and catch the fuel from the VST checking for crap / water either..

Once the throttle is fixed, see if the issue stills exists on smooth water and/or with a small auxiliary fuel tank plumbed direct to the problem engine(known fresh/good fuel).




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