9.8 Mercury "coughs" when cold!

[Rodman738]

Im working on a 9.8 mercury in think 78.Motor starts fairly easy but until the motor warm up it will randomly cough.After it warms up runs fine. Motor has new cdi ignition. Have tried different coils. Have not tore into carb yet! Any words of wisdom would be appreciated!!

 

[flyingscott]

Leave the choke on longer or adjust the low speed mix screw if it has one. It's called a lean sneeze.

 

[racerone]

Open the low speed mixture needle 1/8 turn at a time and test.-----Some 9.8 motors have a provision for a thermostat and some do not have one.-----And there could be other issues as well, crankshaft upper and lower seals might need replacement.

 

[Rodman738]

Thanks for the advice I will definitely work on the low speed idle mixture setting!

 

[Rodman738]

Adjusting the low speed needle did the trick! Starts without the sneeze! Thanks for the advice!!

 

[green4themoney]

Im having the same prob with my 9.8. It helps backing the idle mixture out when cold, but than too rich while running lol

 

[green4themoney]

Open the low speed mixture needle 1/8 turn at a time and test.-----Some 9.8 motors have a provision for a thermostat and some do not have one.-----And there could be other issues as well, crankshaft upper and lower seals might need replacement.

Do you know where to buy the 9.8 exhaust cover with the thermostat? Im thinking it stays a little rich with the motor still cold i.e excessive idling and no load on motor

 

[racerone]

Likely won't find it on AMAZON.------Try your local Mercury dealer to see what you need.