Carburetor question???

[rhillman75]

I have a 1999 Mariner Jet 30 3cylinder 2 stroke outboard. I have a dumb questions... I say that because I am a complete fuel-injected guy and really am questioning myself. I just did a timing and syncing operation on this motor. The service maunal states that the sync the carbs you should loosen the screws for the links to the top and bottom carbs and for the cam followere until the throats are shut then tighten. I did this and I notice that if I go into wide open throttle and look into the throats of the carbs... the only one that is wide open is the cam follower linked carb while the others (top and bottom) are only open about 3/4 the way. So is it improper to make the cam follower linked carb (middle) fully open and then adjust the top and bottom carbs to full open as well? I know it states to make adjustments but it does not say to use the controls to perform a wide open throttle and then adjust them that way. The only way I can get all 3 to fully open is to have the motor at wide open throttle to get them adjusted to fully open throats. Any thoughts???

 

[roncoop75]

Re: Carburetor question???

I noticed this on mine also. Whoever set it up just left it like that.

When I would grab the cam follower and slowly start to open up the throttle plate the middle carb wouldn't move initially. There was play in the plastic linkage between the two. I loosened the coupler with the screw on the second carb and took the play out of it, making sure that when the top one was closed, the second one was all the way closed. This seemed logical to me because on the linkage you can see (at least on mine) there is a an arc shaped slot on the linkage to make this adjustment with. The bottom carb linkage had the same play (and same slot) in it so I did the same to that coupler. They now all close evenly and open 90 degrees at WOT.

 

[rhillman75]

Re: Carburetor question???

So I guess my next questions is... in order to botain a sequence of WOT and full close should go ahead and shift the commander to wide open throttle then adjust the carbs according to that and just make sure the carbs are closed when I shift back to neutral?

 

[Traceyh]

Re: Carburetor question???

The cam follower is kinda what sets your idle, when you do the sync operation, you MUST make sure the cam follower is NOT touching the throttle arm.
Then set all to closed, and you will be golden.

 

[rhillman75]

Re: Carburetor question???

I understand the position of the cam follower. It has about a penny thickness worth of spacing between it and the arm itself. My problem is that with the second carb (cam follower) fully at WOT the top and bottom carb are only about 60% open. My question was... should I adjust them to full open with the commander at WOT. For right now that is how I have all 3 carbs set and with that setting they all close. It just doesnt state that in the manual. I do not want to do any damage, but the way I have been running the motor this year before looking at what they were doing was the issue. The way it has been running is at WOT the second carb was fully open at 90 degrees and the top and bottom were about that inital 60% open, which is what brought me to sync thme with the commander at WOT and then fully opening the top and second carbs.

 

[Traceyh]

Re: Carburetor question???

You wont "hurt" anything by doing it that way, but you may not have a proper idle. I believe the answer to your main question is, Yes, they should all be wide open at WOT. If they are, then they should also be all closed at the same time.