04 90hp help

[supersoaker548]

Hi guys ... I have a merc 90hp 4 stroke , just adj. carbs and was looking at the vac. gauge and rev.it up the two bottom cyc. drop vac about 10lbs and the top two only dropped about 4 -5 lbs

if I'm thinking right the bottom are good and top something is bad

looking for some ideas and where to look ?????

will run comp. test when I get back home

Thanks

 

[supersoaker548]

I'm sorry LOL..4-5 " not lbs

 

[Silvertip]

Could be as simple as the carbs are not synchronized such that all throttle plates open at exactly the same time and the same amount. Since you had the carbs off to work on them, synchronization is certainly the possible cause.

 

[supersoaker548]

I had just did the synchronization and a/f adj and rev it 1 last time and watching the vac. gauge when I saw this happen.
it has what looks like a accelerator pump on the side of the carbs 1 for bottom 2 and 1 for top 2 . but having a hard time finding any thing on them or how to test them

 

[supersoaker548]

[SUP]Thanks silver for the reply found problem blown head gasket [/SUP]