1979 Merc 120 HP - Boat won't start

[Bane333]

Hi,

After storage this winter my boat won't start.

The key turns the engine and it does try to start so I know the starter is fine.

I checked the spark plugs by taking them out individually and grounding them to a ground to see a spark and no spark.

I also checked the lead wire from the ignition coil for a a spark by holding it near a ground and still no spark.

Any issues what it could be?

Would faulty points in the distributor not allow the ignition coil to spark? Could it be the coil itself?

Your thoughts would be greatly appreciated.

Thanks.

 

[GA_Boater]

Does the boat have a man overboard lanyard, which would kill spark if not attached.

 

[alldodge]

See if you have 12V to the + side of the coil

If that is good, remove distributor cap and clean and adjust points, if not replace them with condenser

 

[Bane333]

No, there is no kill switch.

 

[Bane333]

See if you have 12V to the + side of the coil

If that is good, remove distributor cap and clean and adjust points, if not replace them with condenser

Thanks. I would use a multi-meter on what setting? continuity? ohms?

 

[alldodge]

Thanks. I would use a multi-meter on what setting? continuity? ohms?

Volts DC
Your looking for close to 12V, but if the points are closed when you take the reading it will be a bit lower

 

[Bane333]

Volts DC
Your looking for close to 12V, but if the points are closed when you take the reading it will be a bit lower

Thanks. I will give that a shot. Would bad points prevent a spark from the ignition coil?

 

[alldodge]

Thanks. I will give that a shot. Would bad points prevent a spark from the ignition coil?

Yes, When the points close, this charges the coil, when they open this releases the charge down the plug wire. The points must be adjusted so when the distributor rotor is turning, it opens and closes with each plug wire

 

[Bane333]

Thanks for the video. Very helpful. It just may be the points then. I will order the kit.

When I install new points does anything need to be adjusted? or just install in place of old ones?

 

[alldodge]

The point gap must be adjusted to .022 and when the motor is running it should have a dwell angle between 28 to 34 degrees. Probably don't have a dwell meter so try and get the gap adjustment correct and all good

Timing is set at 8 BTDC

https://www.howacarworks.com/ignitio...breaker-points

 

[Bane333]

Thank you!

I will let you know what happens.

Have a great day.

 

[Bane333]

Just an update. I checked the ignition coil for continuity and it was fine.

I also cleaned the points today too with newspaper. There was some gunk in them. Still don’t look as clean as I’d like them to be but I don’t want to use sandpaper on them. Afraid it will ruin them.

Tried starting the boat after cleaning and it still cranks and turns over but no spark

also tried starting it with the tacho wire off, nothing.

Ideas?

 

[alldodge]

Nothing wrong with sand paper or even a file, your not going to damage them.

What kind of voltage do you have at the + side of the coil

 

[Bane333]

Nothing wrong with sand paper or even a file, your not going to damage them.

What kind of voltage do you have at the + side of the coil

I used some sand paper to clean the contact points and still nothing.

the voltage reading I am getting from the plus side of the ignition coil is 11.5-11.96v.

i haven’t changed the spark plugs yet or the ignition cables, should I give that a try?

also I noticed that there is like a circular piece of fabric in the middle of the distributor. I clean it as it was turning black. But what is that for?

thanks again for your help.

 

[alldodge]

The cloth piece is to oil the distributor. Take a few drops of oil and put them on the cloth, doesn't need much

I would replace the points and condenser before replacing anything else.

You should be able to get spark with just the distributor and the cap off. Remove dist cap, and bump the starter until the points are closed. Take a small piece of wood (stick, non-metallic) and open the points with the key on, you should get a spark.

 

[Bane333]

The cloth piece is to oil the distributor. Take a few drops of oil and put them on the cloth, doesn't need much

I would replace the points and condenser before replacing anything else.

You should be able to get spark with just the distributor and the cap off. Remove dist cap, and bump the starter until the points are closed. Take a small piece of wood (stick, non-metallic) and open the points with the key on, you should get a spark.

Success! I got it started. Thank you for your help.

I ended up changing the spark plugs and it fired right up after I cleaned the points again.

I took it out on the water for a bit. It runs fine but after a while I get a whining noise from the engine. When I turn the engine off and start it up again the whining noise is gone.

I took a video today so you can see what I'm talking about.

Any ideas? loose belt?

 

[Scott Danforth]

Every spring. No exception

Take your wifes nail file and file the points, gap the points, verify dwell, set timing, then go boating

 

[alldodge]

The noise sounds to me like a bearing, either the alternator or water pump

 

[Bane333]

The noise sounds to me like a bearing, either the alternator or water pump

How do I determine which one?

 

[alldodge]

Remove the belt and feel for roughness and see if they spin easy. Look at the front of the ALT to see if the vanve blades on front have been scratching the front