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8 hp Mariner Won't Stay Running...

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javadano
Deckhand

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USA
15 Posts

Initially Posted - 07/05/2005 : 19:49:16

After a 17 year dream/wait I bought my 1980 Cat 25. It came with a 1979 8 hp 2 cylinder, 2 cycle Mariner Outboard. The previous owner had nothing but great luck with the motor, taking her to all the Great Lakes, even taking her through 12 foot waves on Lake Superior. Since I bought her, I have had her out four times now. The first time, after an hour and 15 minute drive, 45 minutes stepping the mast, etc. etc. the motor did not start. The second two times, I got her out on Lake Michigan, I had to wait for three bridges (perfect timing with the train trestle...twice), which ideling the motor for so long, the motor just wasn't cooperating. I had to take her in with my wife on the tiller, while I hung over the side pulling/pushing the choke in and out...even after I cleaned the plugs...two days ago, i took her out for fourth time. It was a perfectly beautiful day. 74 degrees. 10-15 mph winds...gorgeous! Got the mast stepped. Sails in place. launched her in the water, and the motor...once again...didn't start. After taking the motor apart, the pawl was in six pieces, and the pawl spring was no where to be found. Searching the internet for these two parts...I cannot find anywhere to buy them. Anyone have a "favorite" place to buy parts? Please help me. My wife is loosing confidence.

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 07/06/2005 : 00:02:24

In a bit of irony, you've discovered that one of the most important things on a sailboat is the engine. Having a reliable engine is not just a convenience, but is a safety item and a marriage saver too.

Here's what I've learned in 40+ years of experience with 2 strokes.

1) Old gas = No good. If it's been in the tank too long, get rid of it. 2 stroke problems? Always start with fresh pre-mix.

2) Old gas mixed with New gas = Old Gas. Think of it as the "Identity Property" for gasoline.

3) Get good quality oil (I like synthetic) and mix in the exact ratio recommended for your engine... no more, no less. Mix with premium gasoline for best results and a bit longer life in the tank.

4) New spark plugs are a 2 stroke's outboards' best friend. Have a couple sets of brand-new extras with you, properly gapped. If in doubt, change 'em out. I've had best luck with NGK plugs in Japanese-built engines. You may want/need to go a heat range higher if you have a lot of low-speed use.

5) You may need a carb cleaning/adjustment. Haven't fooled with a Mariner for ages, but I don't think they were all that complicated in the carb dept.

6) A 1979 motor is starting to get pretty old. (depending on how much the previous owner used her) you might get a compression check.

www.marineparts.com seems to have a good selection of Mariner parts... haven't done any business with them.

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 07/06/2005 : 08:47:25

javadano,

I agree with what ClamBeach said.

Fresh premix, clean out carb, change plugs, compression test.

And while you're messing around with the plugs out, check spark. With a new spark plug hooked up and grounded against the cylinder head, when you spin the motor over you should see a thick bright blue-white spark at the plug gap. You may even be able to hear it snap. If the spark is thin and yellow (or not visible at all) even with the engine spinning over smartly, then check the igition system for problems. A shop manual for the motor can be extremely helpfull in finding and fixing problems quickly and confidently.

-- Leon Sisson

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 07/06/2005 : 09:55:16

Also check for air leaks in the lines from the fuel tank to the fuel pump to the carb. I once had a gasket go on a fuel pump which caused all sorts of idling problems.

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JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 07/06/2005 : 15:43:50

A new Nissan/Tohatsu 9.9 HP extra long shaft 4 stroke weighing only 88 lbs is $1900. You can even get electric start, but expect the motor to start first pull, every time, idle all day, and get 10 to 15 miles per gallon. No pre-mix, no smoke, so quiet you'll forget its running.

25 years is a long time for a 2 stroke outboard.

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 07/06/2005 : 18:56:15

Had a few more thoughts...

Make sure fuel tank vent is open. No vent = no fuel = engine dies and won't restart.
Don't overpump the primer bulb... when you feel resistance stop.
Don't underpump the primer bulb... make sure you feel the fuel flow to the carb.

Edited by - on

Tom Potter
Master Marine Consultant

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USA
1913 Posts

Response Posted - 07/06/2005 : 21:18:48

My first sail boat had a 4hp mariner on it. I had the same problems you discribe. Changed gas and plugs, the problem was still there. What I found is the 4hp had a small bowl on the bottom of the carberator that will collect water. Mine had a small brass drain screw that I could drain the water out. I would have to drain it every once in a while to keep the ole girl running. Hope this helps.

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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.