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99 mercury 2 stroke wont run

M

magnumden

New member
"Have a 2 stroke 9.9 86 model,

"Have a 2 stroke 9.9 86 model, low hours ran great for years, last time out started acting up and would only run right on choke, then after a while would run great with no choke. Next time out wouldnt start. First pull fired, then nothing. Cleaned plugs, semi fouled, great spark, nothing. Then carb cleaner in carb and instant start, and ran till cleaner gone. Clean fuel, clean filter, gas punps in line to carb. Squirt gas in carb runs till gas is gone. suggestions? fuel pump? need help thanks den"
 
"Maybe the fuel pump, but just

"Maybe the fuel pump, but just as likely either the low speed jet or the float valve is all clogged up.

The carb and the fuel pump are all one unit on this model, so why not pull the carb, take it apart and give it a good soak in cleaner. Then put it back together with a new fuel pump diaphram and some new gaskets (about 20 bucks for everything).

Odds are high, that would cure all the issues..."
 
"Graham, thanks for the advice

"Graham, thanks for the advice, it is what I expected but wanted to confirm. Thanks again for being informative and gentlemen on this site. Denny"
 
Somthing this age could have p

Somthing this age could have popped the lower main seal. Than it only runs on the top cylinder.
 
"Maybe - it definately sounds

"Maybe - it definately sounds like it's getting too much air/not enough gas (or no gas somewhere).

I have an 86 and an 87 9.9, both with well over 1000 hrs each (and probably closer to 2000) and haven't really found them hard on too many parts.

A bad base gasket would cause problems too, but normally you get a cough/sneeze or backfire when that is shot (lost a couple over the years).

And I do have a bad upper crank seal on one of them - haven't got around to fixin' that yet (pain in the butt), but not causing performance issues yet, so I have left it alone for the past 3 or 4 years.

Merc has a nice "repair kit" (amongst others) for the carb on these - contains everything to rebuild the carb AND the fuel pump in "one box" - ya, goes for about 75 bucks, but it's an all in one, and that can usually cure everything that ails these little motors."
 
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