1998 Mercury Force 90 HP Outboard Carb Question

bwillaub

Seaman Apprentice
Joined
May 12, 2008
Messages
40
Just got my boat back on the water after a couple of months of powerhead trouble. The motor ran great until the powerhead decided to throw a piston rod thru the side of the block. Ordered a powerhead. Installed it. Having problem with idle. Will not start without throttle and dies when putting into neutral. Is there a video out there somewhere that will show me how to set proper idle? One more thing: I rebuilt the fuel pump. When I opened it up, I found that the black rubber washers were not installed. Only the thin plastic washers were being used. Any ideas on why this would be? Thanks. Bob
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,926
The pump uses thin plastic diaphragms instead of the rubber in the old ones.
.​Ones as good as the other.
If you backfire it can hurt both styles.

Top few posts in this forum cover setup and timing.
 

bwillaub

Seaman Apprentice
Joined
May 12, 2008
Messages
40
Thanks, jerry. I installed both with the thin plastic ones on top of the rubber ones. Thot the diagram showed to use both. Is this why I don't have the fuel flow for idle?
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,926
You just added way more resistance that it can overcome.
​Use the newer plastic.
Making sure not to bend or warp them.
If warped they don't seal and fuel can leak into a piston.
 
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