90hp mariner running went dead, now sluggish

rosser1

Petty Officer 1st Class
Joined
Apr 5, 2009
Messages
360
took the boat out first time this yr, it ran great last yr. and ran great in the yard on muffs. But i cranked boat in yard the night before, ran good, next morning put boat in water cranked and was running good, but was in idle zone so was going pretty good and motor started running bad, idle higher and died. Tried to start it back and nothing, chocked and nothing, primed and chocked and tryed to start. so i had to reajust carbs idle screws and ran good, at top speed still sluggish. i was wondering if idled to high would make it motor run sluggish? Thanks.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: 90hp mariner running went dead, now sluggish

Verify the mechanical condition of the motor by testing compression, then you KNOW you have a solid foundation.

Next, test spark on each cyl, you need at least a 7/16 inch hot blue arc to make any power, anything less is a problem that needs further testing.

After that it is all in the fuel delivery. Disconnect the fuel hose between the fuel pump and carbs, point it into a suitable container and crank the motor with the lanyard pulled so that it won't start, you just want to see how well it pumps fuel. You should have a strong pulsed flow the diameter of the hose opening and at least an inch out, any less and the motor will not make full power at WOT.
 

rosser1

Petty Officer 1st Class
Joined
Apr 5, 2009
Messages
360
Re: 90hp mariner running went dead, now sluggish

ok thanks, only thing is the landyard is connected to switch. boat is 81 and motor is 79 model. when landyard is pull it turns switch off.
 
Top