Was loaned a mid seventies 20 hp 2-stroke. (Merc model 200). Under the cowling looks as new - REALLY! Has new gas tank and lines. Plugs are new. Wiring looks great.
It starts easily, accelerates quickly and runs smoothly at all revs. From cold start, after 5 or so minutes the revs drop to trolling speed. Only feathering the choke gains back a few rpms, but not enough to get boat back on plane. Retried the second day with same results. Doesn't stall, just won't rev up.
Discussions with others point to carb problems based on the reaction to choke. I'm not convinced as the timing of the problem suggests to me it could be heat related.
(Engine cooling system seems fine. Water output seems normal)
Any suggestions where to start?
It starts easily, accelerates quickly and runs smoothly at all revs. From cold start, after 5 or so minutes the revs drop to trolling speed. Only feathering the choke gains back a few rpms, but not enough to get boat back on plane. Retried the second day with same results. Doesn't stall, just won't rev up.
Discussions with others point to carb problems based on the reaction to choke. I'm not convinced as the timing of the problem suggests to me it could be heat related.
(Engine cooling system seems fine. Water output seems normal)
Any suggestions where to start?