Strange problem with 3 L mercruiser carby

[Oldsalt&au]

gidday all, my 3L mercruiser has been running a bit rough so I redid the timing, it was a little out, then it was the carby's turn. It's a 2004 model & doesn't seem to have a mixture screw. The other thing I did was to hold my hand over the carby throat & there was no change in engine speed & no suction. My old Mechanc's brain is telling me wt*. Can anyone explain why this is so,(no not my brain). Cheers.

 

[bondo]

The other thing I did was to hold my hand over the carby throat & there was no change in engine speed & no suction.

Ayuh,..... That, ^^^, is physically impossible,.....

I'd verify the fuel in the tank is still good clean gasoline,....
Change the fuel filters, 'n pull the carb, to rebuild it,.....

 

[fastjeff]

Huh! Double huh!


I suspect you have a major vacuum leak there, Mate.

Jeff

 

[RicardoMarine]

................ The other thing I did was to hold my hand over the carby throat & there was no change in engine speed & no suction.

Choking off the carburetor's air supply should have immediately created an excessively rich scenario, causing the engine to stall out.
It is very strange that this did not!


.

 

[Bt Doctur]

If its a TKS carb the mixture screw is under the anti-tamper cap

 

[Lou McGoldrick]

If its a TKS carb the mixture screw is under the anti-tamper cap

This probably doesn't have anything to do with your problem, but when I bought my 2004 3L it ran rough.
new plugs, wires, distributor cap, and rotor cured that.

 

[Oldsalt&au]

Thanks