200 Optimax Idle niggle

[PeterM]

I recall reading ( but cant find now) a thread about rough idle on one of these . My old one has started doing it now ....

I 'think' one of the knowledgable guys said something about an air valve may be the issue...?

But its almost hunting at anything up to 1500 revs , and after thats its sweet. Not a misfire, just a slight surging feeling for a second then fine for 10 secs (ish) then the same again.

Any ideas - anyone find the thread ?

The new owner has a merc engineer but wondering if I point him in the right direction it may be quicker/cheaper for the owner, gain me points so I can keep using it

Ta

Pete

[jambo]

Pete why dont you give uncle al a pm I'm sure he would fix you up

[uncle al]

it could be the throttle position sensor either sticking or knackered, ot the throttle roller got a wear groove in it, i am now on holiday for a fortnight if this is not the problem give either Robby or Sam a ring at Blackdog marine

[HUMBER P4VWL]

Different block, but our 175 used to hunt at idle, did it fir two seasons, it got worse over time, then started missing sometimes. Then it got v bad, but intermittent. Tried throttle sensor, idle position, injectors!, spark plugs etc etc. Turned out to be a chafed wire on the entry in to to the engine. V annoying! Worth checking the loom where it moves and could rub.

We got a new loom in the end.

[martini]

Sounds much like one of mine, ever since I changed the loom it hunts a little bit on idle, runs fine otherwise (or it did till I got to Paris )
I've never looked into it in any great detail, it'll be interesting to hear what the verdict is.