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  #1  
Old August 10th, 2009, 05:58 PM
avius avius is offline
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Default Mercury 90 HP Carburetor Sync gauge

Need to sync my carbs now that I've taken them apart again.... But I'm not sure what kind of gauge I can use I could use some help.... Found this on ebay, but not sure that it'll fit my motors:

http://cgi.ebay.com/ebaymotors/Carburetor-Synchronizer-carb-sync-Gauge-CB-450-500-650_W0QQcmdZViewItemQQ_trksidZp4634Q2ec0Q2em14Q2el 1262QQhashZitem4cea65b67dQQitemZ330350048893QQptZM otorsQ5fAutomotiveQ5fTools

Anyone got any answers? Thanks...
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  #2  
Old August 11th, 2009, 04:33 AM
saumon saumon is offline
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Default Re: Mercury 90 HP Carburetor Sync gauge

You don't need that at all.

In an OB, synchronizing the carbs simply means that they open at the same time. Loosen the link rod, so they'll be all closed, and retighten.
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Old August 12th, 2009, 03:48 PM
avius avius is offline
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Default Re: Mercury 90 HP Carburetor Sync gauge

Thanks saumon I'll do that. That seems perfectly logical now that I think about it. But I wonder why the Seloc book adds in the stuff about the motor needing to be under load and using a sync gauge and all that. Is syncing the carbs anything to do with "link & sync?"
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Old August 12th, 2009, 04:22 PM
saumon saumon is offline
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Default Re: Mercury 90 HP Carburetor Sync gauge

Quote:
Originally Posted by avius View Post
Is syncing the carbs anything to do with "link & sync?"
Yes. Actually, it's the first step of the entire process. After that, you'll adjust the throttle and set the timing.
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Old August 12th, 2009, 06:05 PM
hondon hondon is offline
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Default Re: Mercury 90 HP Carburetor Sync gauge

Is this unit a 2 or 4 stroke?
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Old August 12th, 2009, 07:51 PM
avius avius is offline
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Default Re: Mercury 90 HP Carburetor Sync gauge

Quote:
Originally Posted by hondon View Post
Is this unit a 2 or 4 stroke?
Its a year 2000 4 stroke
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Old August 20th, 2009, 05:22 PM
avius avius is offline
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Default Re: Mercury 90 HP Carburetor Sync gauge

Would out of sync carbs cause the motor to die when WOT in gear?
Doesnt happen in neutral, but in gear under load it boggs then dies.
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Old August 22nd, 2009, 09:12 PM
saumon saumon is offline
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Default Re: Mercury 90 HP Carburetor Sync gauge

I'm not very familiar with 4-strokes engines but in 2-strokes engines, the first thing i'd look for this particular problem would be the fuel pump diaphragm. As yours is a carbed one, it should have a fuel pump too.
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Old August 24th, 2009, 11:41 PM
avius avius is offline
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Default Re: Mercury 90 HP Carburetor Sync gauge

Quote:
Originally Posted by saumon View Post
I'm not very familiar with 4-strokes engines but in 2-strokes engines, the first thing i'd look for this particular problem would be the fuel pump diaphragm. As yours is a carbed one, it should have a fuel pump too.
Thanks for the advice Sauman. When I took apart the carbs for cleaning I also took apart the fuel pumps (I have two per motor). Aside from a little varnish from the old fuel, they appeared to be okay. Naturally, I cleaned them up. The diaphragm itself was fine, had no tears or holes that I could see. I spoke with the Mercury outboard support guys and they told me that the only way to sync my carbs was to get a hold of a sync gauge set. This is the one I bought online : http://carbtune.com/. Haven't received it yet, but I'll be sure to post the results. HOPEFULLY this fixes my problem! I'll definitely post my findings though so that it may help the next guy that has similar problems.
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