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Catalina/Capri 25/250 Sailor's Forums

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Tohatsu Outboard

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ngrinich
1st Mate

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28 Posts

Initially Posted - 10/03/2010 : 20:48:14

I have had my 9.9 Tohatsu for a little over a year now and am finally getting around to connecting the electric start. When I first got the outboard, I engaged the starter for a moment in the garage with the motor connected directly to a 12 volt battery. It turned the motor over just fine. Since then, I have removed the starter cables from the motor and have just used the pull start. To connect the electric start on the boat I have run very large size gauge marine quality wire from the motor via a 30 amp in line fuse to the battery. Now, when I try to start the motor with the electric start, it blows the 30 amp fuse. My question is, should I keep the 30 amp fuse? I cannot find anything in the owners manual about putting a fuse in line but I recall running across that recommendation on one of the posts. I have checked with the ohm meter to make sure there is no short in the wire circuit and it checks out ok. For now, I am back to the pull start.

Nick
C-25 FK/SR '87

Edited by - ngrinich on 10/03/2010 20:51:58

Mark Maxwell
Captain

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Response Posted - 10/03/2010 : 22:02:28

I can't see a reason to put a fuse there. I also think the amp draw would be much higher than 30amps. Now on the charge line from the alternator then yes fuse that one for sure. It should be installed by the factory somewhere in the motor head.

So, I'd say remove that fuse on the start line, make sure you are using at minimum 10ga. wire. Isolate the battery with a switch and enjoy.

Edited by - on

Dave5041
Former Mainsheet Editor

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3758 Posts

Response Posted - 10/03/2010 : 22:46:08

Call a dealer/service shop to find out what the starting current is for the motor. I suspect that it is well over 30A. It won't be anything like 150 HP motors that can draw 800 - 1000 A, and I couldn't find anything in a quick web search, but 30 A or 360 watts seems really low.

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britinusa
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Response Posted - 10/04/2010 : 05:12:29

My Dealer installed Tohatsu 9.8 has only 2 electrical cables running from the engine to the battery. No fuse

I could not find the fuse size either, I did read that one owner has a 125A fuse inline, but that cable is sure going to get hot prior to that puppy blowing.

Normally a fuse would be inline as close to the battery as possible. That would require that it be in the trunk. The engine is normally really easy to start with the pull cord. I assume that if the battery/starter fuse did blow, then the problem would be in the starter motor, and unless seized into the starter ring, the engine would still start with the pull cord.

Paul

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tinob
Master Marine Consultant

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1883 Posts

Response Posted - 10/04/2010 : 06:57:36

I also have two lines direct to the engine from the battery without fusing.

Val on Calista # 3936
Patchogue, N.Y.

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John Russell
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3444 Posts

Response Posted - 10/04/2010 : 07:15:38

My 2005 Tohatsu has a fuse under the engine cover in the forward portside corner. Essentially, it's right above the start button. It's in a yellow case. I know this because I connected the cables backwards a couple of years ago and took forever to figure out why the motor would pull start just fine but not crank when I pushed the button.

I think your addition of a 30 amp fuse is just duplicating the one that may already be blown.

Go to this website: http://site.nissantohatsupartsstore.com/PartsCatalogMFS9.9C-15C-20C20081.pdf

Look in the middle of page 30 of the document and you'll see items #24 (Fuse Cable) and #24-1 (Fuse) The parts list says it's 20 amps.

Edited by - John Russell on 10/04/2010 07:28:23

Ed Cassidy
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Response Posted - 10/04/2010 : 16:24:38

I think the 20 amp fuse is intended to protect the charging system. A side effect is that when blown by hooking up the battery backwards, the starter solenoid does not work, preventing the started motor from spinning. I don't think you will ever find a fuse inline with a starter motor. The draw is just too unpredictable. A cold day and a cold engine will cause the engine to spin over much slower than on a warm engine, causing a dramatic increase in amps compared to a warm engine.
Ed

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John Russell
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3444 Posts

Response Posted - 10/04/2010 : 16:54:41

All I know is that my engine started like a charm after I replaced the fuse.

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Voyager
Master Marine Consultant

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5378 Posts

Response Posted - 10/04/2010 : 17:06:55

Ed - good point on the variability of the current draw.

Nick - Here's why I'd recommend a fuse on ANY wire pair coming from (or to) your battery:

Big fat wires can draw a lot of amps. If a short developed somewhere along the line (say, near the engine end), you could draw a huge amount of current (> 100A). That would quickly melt the wire which would start a fire in the plastic/fiberglass of your boat. The boat would burn to the waterline.

So, I would place a fuse on the positive lead near the battery end of the starter cables.

For my 8 HP Honda engine, Honda recommends an 80A fuse for the starter. According to the shop manual, the starter motor draws < 40A with no load and < 80A under max load. I currently have a 60A fuse in line, and have not had it blow out yet. I sail only rarely when temps are below 50 degrees.

You are probably familiar with common small inline fuse holders with #10 AWG wire. These are usually used up to about 30A. You would not want to use this type for a starter. However, you can find high amperage fuse holders and fuses at West Marine.

Here are a few suggestions:
Maxi Fuse Block for 30-80A Loads
BLUE SEA SYSTEMS - Terminal Fuse Blocks - Appropriate for DC Main, inverter, windlass, and bow thruster circuit protection.
BLUE SEA SYSTEMS - Maxi Fuses - this is a larger size of a conventional inline fuse. For example: 60 Amp Maxi Fuse P/N 594384 5141

The main benefits are:
1. If you reverse wire your engine one year, the fuse will save it.
2. If the cables short out somewhere down below, the fuse will save your boat.
3. If it's too cold to sail, the fuse will blow!

If the engine has a charging circuit, it probably supplies between 5-10 or 6-12 amps. That's well below the fuse rating, so no problem there.

Edited by - on

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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.