Starting Problem - need help

Sundog · Posted: Sat Apr 09, 2011 12:29 pm Post subject: Starting Problem - need help

Hi All,

Would love to borrow your knowledge. I have a 50 HP Tohatsu and it will not start with the key. I turn the key and it does the usual high pitch noise saying it is getting juice but when I turn the key it does not make any noise at all. I am able to use a rope and pull start the motor and it starts right up. Any ideas what might be the culprit?

Thanks,

Joe

Dan McNally · Posted: Sat Apr 09, 2011 1:13 pm Post subject:

Sounds like the starter is hanging up, pull the cover and see if when you turn the key that the gears on the starter move out to engage the flywheel. It should loosen up if you do it manually a couple of times.

thataway · Posted: Sat Apr 09, 2011 1:27 pm Post subject:

Be sure that the shifer is in neutral (work it back and forth) there is a safety which will not allow starting in gear.

The most common cause is not putting in the safety lock with the lanyard--but that usually does not allow alarm.

If the engine is tilted up too much there is also a safety interlock and it will not start.

Check all of the connections from the battery (plus and minus) clean them with a wire brush, be sure that any nuts are tightened with a wrench--not using just wing nuts (if you do, use a wrench on them). Check connections on the selenoid (which could also be bad)--you should hear the selenoid click if the starter Bendix gear is stuck.

As above, if it is the bendix gear, then you may want to work it by hand (battery disconnected), and then spray the shaft with silicone. Depending on the gear, you can also put lithium grease on the gears and flywheel if sticking there.

I like to spray my entire engine with "corropsion block" about every 6 months, after cleaning connections and the block.

50 hp will give only marginal speed on the C Dory 22. You may end up wanting to put a second 50 on it, if this is a new motor...

forrest · Posted: Sat Apr 09, 2011 2:45 pm Post subject:

I'm not saying I know what your problem is but here is some additional info. On some smaller motors, and I don't know what Tohatsu is like, you don't have a starter solenoid but you do have a starting relay. If the relay is burnt out, or the control wiring from your switch is corroded or you have a solid state relay,you won't hear anything. If you do hear the starting relay 'clicking' in, the contacts inside the relay may be corroded or burned out which in that case the relay must be replaced. If you have an digital volt-ohm meter, you can measure the voltage drop or resistance across the relay depending on which scale you are using. I guess what I'm trying to say is don't immediately blame the starter if you don't hear anything. Pull the starter and hook it directly to the battery with some jumper cables to see if it works. Disconnect the power lead from the relay to the starter and see if you can read continuity across the relay with the key on and turned to the far left in the start position. If you are going to check for voltage drop across the relay you must have the starter hooked up so there is a load (if the contacts are bad they may show 12 volts across them without a load but will drop significantly when under load). If the starter is bad and all your connections and relay are good, usually smoke is released from the starter. That usually means worn bushings, bad brushes, or open windings(from letting out the smoke).

tsturm · Posted: Sat Apr 09, 2011 5:08 pm Post subject:

forrest · Posted: Sat Apr 09, 2011 9:04 pm Post subject:

Oops. I should have said turn the key to the far right in the start position instead of left. I guess I need to proof read a bit more. The difference between a solenoid and a relay is while both have a set of large contacts to control starting current to the starter motor, the solenoid also does mechanical work by engaging the the starter pinion with the ring gear of the flywheel. When the solenoid is energized, it operates a plunger or lever which forces the pinion to mesh with the ring gear and closes a set of large contacts to supply starting current to the starter. The starting relay only closes a set of large contacts, which supplies starting current to the motor. The centrifugal force of the rotating starter forces the pinion into the ring gear when you have a starting relay. I'm not a mechanic but I think on smaller motors, that use smaller starters, a relay instead of a solenoid is used. Not sure about that though. Edit: Your keyed switch supplies a small current to energize the solenoid or relay and the solenoid or relay then closes a large set of contacts that provide the starting current for the starter.

Sundog · Posted: Sat Apr 09, 2011 11:17 pm Post subject:

Thanks a bunch all - I actually ended up selling it with the problem today but I still hope to figure it out tomorrow and will use your ideas for sure.

Cheers from the Sundog Crew!

hardee · Posted: Sat Apr 09, 2011 11:47 pm Post subject:

Sundog,

Congrats on the sale and GO TWINS --engines I mean Thumbs Up

and in your case go Triplets too or should that be three. Smile

Looking froward to following your trip north, and hopefully meeting at Friday Harbor too.

Harvey
SleepyC Moon

forrest · Posted: Sat Apr 09, 2011 11:55 pm Post subject:

One final thought. There are no contacts in a solid state relay. You will hear nothing. You have to use a meter to check out the relay.

thataway · Posted: Sun Apr 10, 2011 9:32 pm Post subject:

Forrest makes some good points--and on many engines there are both relays and solenoids. When you get into modern larger RV's then there are multiple relays and many are solid state. I suspect that is probably true on many of the larger more complex boats. The nice thing about C Dory's is for the most part they are simple.