Yamaha 9.9 4-Stroke Auto Choke

[Inselaffe]

Morning!

I am about to start trying to find out why the automatic choke on my outboard doesn't disengage as the engine warms up.

Anybody had any experience with these / can offer any tips?

More details:

1990 Yamaha 9.9HP 4-stroke (white)

Engine number starts with 6G8L

Choke is activated by vacuum from inlet manifold which pulls down a plunger (i.e not the electrically operated later version).

The choke comes on (ie plunger is pulled down) but doesn't come off as engine warms up.

I currently disengage the choke manually by holding the plunger up with the little pivoting clip, but I think that this method is maybe causing other problems in the slow running as it warms up.

It used to work a year or so ago!

Any help most gratefuly received

Edit: Am I right to think that plunger up is choke off?

 

[Rakos]

Hello,
I am having the same problem now: the mptor 'surges' until it has warmed up. I am pretty sure it is the auto choke. I was just wondering if you soled the problem? I can be email to john@rakos.com
Thanks,
John


I am about to start trying to find out why the automatic choke on my outboard doesn't disengage as the engine warms up.

Anybody had any experience with these / can offer any tips?

More details:

1990 Yamaha 9.9HP 4-stroke (white)

Engine number starts with 6G8L

Choke is activated by vacuum from inlet manifold which pulls down a plunger (i.e not the electrically operated later version).

The choke comes on (ie plunger is pulled down) but doesn't come off as engine warms up.

I currently disengage the choke manually by holding the plunger up with the little pivoting clip, but I think that this method is maybe causing other problems in the slow running as it warms up.

It used to work a year or so ago!

Any help most gratefuly received

Edit: Am I right to think that plunger up is choke off?[/QUOTE]

 

[Rakos]

Yes, the plunger up opens a jet so it is enriched(on), plunger down plugs the jet so choke off. I am still having the problem. Best would be if I could completely disengage this troublesome bimetal air valve and manually operate the plunger. I tried disconnecting the hoses, but there are many going all over the place. Where can I get a service manual that shows the positio and function of all these hoses?

 

[Rakos]

anybody got a souton yet? Is there a detailed parts/service manual available (need to see where all those little air pirpes go) Where can I buy the bimetal valve? Thanks

 

[NZ Outboard]

Did you ever find a solution to this issue? I have a 1989 Yamaha F9.9hp doing the same thing. It runs for 30seconds, then the choke plunger shoots down and the engine dies instantly. If I lock the plunger in the up position the engine will continue to run.