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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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My 1989 Yamaha 3 cycl. has no vacuum on bottom cycl. its a

Customer Question

my 1989 Yamaha 3 cycl. has no vacuum on bottom cycl. its a 40 h.p. elef. good compression 121.123.125. pull # ***** plug wire while running, nothing happened, just keeps running, pull other plug wires and it dies. a boat shop pulled powerhead, manifold said there was a leak. resealed it, ran fine for 3 or 4 minutes, then droped #3 again. what next, new owner? I had no idea I was running on 2 cyclinders till while running wot the thing took of like it has nos in it. then slowed down again. thanks j.d.
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hi JD, my name is Jason.
Can you be more specific by what you mean by the bottom cylinder has no vacuum?
If you place your hand over all 3 carbs with the engine running, can you feel suction against your palm, or does it spit back at you?
Customer: replied 2 years ago.
no suction on #3 but doesent spit back.
Expert:  Jason replied 2 years ago.
So no pressure or no suction then when you place your hand over #3, correct?