Monmouth00's 1979 20 Hp 2 Stroke Merc

Monmouth00

Petty Officer 2nd Class
Joined
Nov 26, 2017
Messages
198
Hello Everyone,

I'm in the throws of restoring a 16 ft. Starcraft Kingfisher.

I bought the boat with what I think is a 20 hp two stroke Mercury O/B, circa 1979. Because my local lakes are 9.9 limited, someone stuck some 9.8 Mercury decals on it, and it's masquerading as a smaller engine.

After I would prime it with just a few squeezes on the ball, I would notice fuel in the water. Not a lot, but it was definitely there.

It ran great when it ran, but after it warmed up a bit, sometimes it would refuse to go into gear. It would stall, and I'd have to re-start and try to pop it into gear abut a dozen times before I could get moving again. Like I said, it seemed to be totally intermittent.

Then, on my last outing, it just wouldn't achieve higher RPMs. It would struggle and stall. It did not sound like it was running well at all. When I got back to the dock, I noticed I had gone through a ton of fuel. I think it was just pumping it straight out of the engine. I didn't notice anything in the water, but I was concentrating on getting back to the dock, and keeping my son calm (who was worried we were going to have to get towed in again).

The O/B came off the boat and went to a local small engine repair shop. They came with good recommendations and reviews, but since I'm new to outboards, I was wondering if anyone could tell me what I should be looking for in his diagnosis.

I think my gas tank is one of the new EPA-approved tanks, and have read about fuel being pushed through the engine on warm days. Was this a possible cause? I don't remember it being that hot that day, or the tank being any more swollen than usual.

Could it be float valves? Fuel pump diaphragm? Ball bearings? Deviating fratastat?

Doing my best to learn as much as I can, but truthfully, I've never been an engine guy.

Your help is appreciated!
 

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racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
The cowling indicates an 81 / 82 / 83 model.------Check fuel pump.---Check float valve.
 

Monmouth00

Petty Officer 2nd Class
Joined
Nov 26, 2017
Messages
198
The cowling indicates an 81 / 82 / 83 model.------Check fuel pump.---Check float valve.

Awesome. Thank you.

When it was dumping fuel, I thought float valve. Good to hear I'm on the right track.

What on the cowl indicates it's from the early '80s?

Can you tell if it's a 20 or a 25 hp?

Thanks!
 

Monmouth00

Petty Officer 2nd Class
Joined
Nov 26, 2017
Messages
198
Is there any way to get my portable fuel tank to stop oozing oil/gas mix all over the back of my boat?

I've gotten a drip pan to put under the tank because I don't want to ruin my new vinyl.

Thanks!
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
Second look shows the decal on the front to be a 79 or 80 model.---That engine was never marketed as a 25 HP
 

Monmouth00

Petty Officer 2nd Class
Joined
Nov 26, 2017
Messages
198
Second look shows the decal on the front to be a 79 or 80 model.---That engine was never marketed as a 25 HP

Fairly certain that someone changed the decals. I know it's not a 9.8.

Should I assume its a 20?
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,944
The colour/striping schemes are what give a quick reference to the years. The front cover cowl is a 79, the wrap around, 1980 - 83. Biggest 9.8 ever I've seen
There was a 25 marketed back them but it had a real boxy shape to the cowl, and it was a totally different engine
 

Monmouth00

Petty Officer 2nd Class
Joined
Nov 26, 2017
Messages
198
The colour/striping schemes are what give a quick reference to the years. The front cover cowl is a 79, the wrap around, 1980 - 83. Biggest 9.8 ever I've seen
There was a 25 marketed back them but it had a real boxy shape to the cowl, and it was a totally different engine

Shh! Don't tell the Rangers it might be something bigger than a 9.8 under the cowl!

I have to putt around the lake very slowly so I don't call attention to my oversized 9.8!
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
Perhaps these " rangers " are more knowledgeable that you think.-----They can identify motors like that in no time.-----I would hope they get at least some training on this matter.
 

Monmouth00

Petty Officer 2nd Class
Joined
Nov 26, 2017
Messages
198
Perhaps these " rangers " are more knowledgeable that you think.-----They can identify motors like that in no time.-----I would hope they get at least some training on this matter.

God, I hope not. If I'm caught I have to plead ignorance. "Sir, this is my first boat. I know nothing about outboards. It says 9.8 on the cowl!"
 
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