1982 9.8 HP Won't top out

[adominique0313]

Hello, I have a 1982 Mercury 9.8 HP. I replaced the impeller when I bought the motor from a friend. He had it on a 18ft pontoon and he said it never really went over 4 or 5 mph. So I thought I could put it on my 1968 astroglass (boat weight is about 400lbs I am 250lbs so with gear it is about 700lbs) 14ft fiberglass and I thought I would be able to get 8 to 13 mph out of it however, I can only get about the same as his pontoon got (4 to 5 mph) the motor seems to engage in gear OK and the engine seems to rev up OK but that's all I got out of it. So all I can think of is 1. wrong prop 2. rod that engages gear is not pushing the gear forward far enough 3. engine might not be reving up enough. I don't know what the right thing to tear into first is. Any thoughts or help or maybe someone has herd of this before. anyhow thanks for any replys

 

[Scott Danforth]

If the motor was on a pontoon, its most likely a long shaft motor. Is your astroglass a 15" transom or a 20" transom. If you have a 15" transom with a long shaft motor, the prop is too deep

 

[adominique0313]

Thanks Scott for answering so quickly. I guess I for got to add that information. It is a long shaft and the transom depth is 18 inches. The top of the prop is two inches below the bottom of the boat transom. So that means the whole prop + 2 inches is below the boat. So that means it's too deep in the water. Ohhhh and here's the deal I want to use this motor as a kicker motor and because I live in Pennsylvania most of the lakes are 20 hp max. I just bought a new to me 2003 crestliner super hawk 1700 with a 90 hp on it.

 

[racerone]

Need to gather the facts and post them,---What does a compression test show ?------Do you have spark that will jump a gap of 3/8" on both leads , yes or no,----Is the throttle opening fully, yes or no ?------Likely has nothing to to with not being fully in gear.