Tohatsu M50D - fresh battery won't spin fast

[bertschb]

I have a 1995 Tohatsu M50D. I bought this engine used and I've just used it for the first time. It worked great with one exception - I have a new battery that is fully charged but when I try to start the engine it spins very, very slowly. It just barely turns over. After a few seconds the engine will start spinning a little quicker and then it eventually starts. Once the engine is warm it starts quickly. If I shut the motor off for 30 minutes it spins slowly again.<br /><br />I took the battery box cover off today and when I turned the key to the start position to start the engine I heard a sizzling sound and noticed a wisp of smoke coming from the negative post of the battery. Once the engine started I didn't notice any more smoke.<br /><br />When I bought the boat I removed the battery cables from the battery connectors and cut off a couple inches of cable, cleaned the connectors and re-attached the cables to the connectors. They were pretty rusted. The cables are firmly attached to the connectors which in turn are firmly attached to the battery.<br /><br />What's going on? Do I just need new battery cable connectors? What should the voltage be on a freshly charged battery. Mine is 12.8 volts.<br /><br />Thanks

 

[mattsaks]

Re: Tohatsu M50D - fresh battery won't spin fast

I would start by replacing the battery connecters/terminals. Sounds like there is a bad connection there. Make sure the battery posts are clean before you fit the new ones. I have found with the wingnut type battery terminals it is better to throw the wingnut away and put on a ny-loc or similar self locking nut. This will ensure you keep a good tight connection which is very important. Also check the battery voltage when the engine is running to make sure it is charging.

 

[igness]

Re: Tohatsu M50D - fresh battery won't spin fast

I agree with Matt. Every connection should be thouroghly cleaned. connecter to cable, "both ends of both cables", connecter to battery, and connecter to block and starter.<br />Here's a couple of other ideas. <br /> (1) It may also be that your cables are too small of a gage to carry sufficiant current.<br /> (2) If the battery you have now is a deep cycle, it will, by its very nature, not have as many cold cranking amps as standard battery.<br /> (3) I'm not familiar with this engine, if it's an outboard, this doesn't apply, but if it's an inboard someone may have put to heavy of a motor oil in it, which would cause it to turn over slower. Though a cold engine will always turn over a bit slower than a warm one.

 

[bertschb]

Re: Tohatsu M50D - fresh battery won't spin fast

It's not a deep cycle battery and it is an outboard engine (50HP). The battery cables are the factory cables that came with the engine.<br /><br />Any idea what would cause the battery to make that electrical "sizzling" sound and the tiny wisp of smoke from the negative terminal? I think that's where the problem is I just don't know why it's doing that.

 

[mattsaks]

Re: Tohatsu M50D - fresh battery won't spin fast

It will be a bad connection at the battery post.<br />Good condition battery terminals (not rusted!) are a must. they also have to be tight. I have seen a battery terminal put on "tight" after being knocked on with a hammer and it still sparked and smoked and barely turned the motor over. They other thing to check is that the other end of the battery cable (the negative one)has a good connection on the engine.

 

[bertschb]

Re: Tohatsu M50D - fresh battery won't spin fast

OK, I replaced the battery cable connectors with new ones. They fit perfectly on the battery posts and everything is tight. I tried starting it and didn't get any smoke or sizzling from the negative post. But, it still turned over slowly. The only difference is this time it started spinning faster after just a few seconds (maybe 4-5). It then started spinning quickly and started right up after that. I still think with a fresh battery it should have NO trouble spinning that little engine like a turbine.<br /><br />It's going to the shop next week for a new tach and trim gauge. I'll let the guy check it out then.

 

[mattsaks]

Re: Tohatsu M50D - fresh battery won't spin fast

No smoke is good! Now you need to load test the battery to make sure it's up to it. If it is, check all the wiring to the starter and all the earths. Look for bad or loose connections, or any corrosion on the earths. If there are no problems with that, you need to test the starter. Also, what is the battery rated for in terms of cranking amps?

 

[bertschb]

Re: Tohatsu M50D - fresh battery won't spin fast

I did a cursory check of the hot battery wires on the motor but not the ground wire on the motor. I'll try to do that today. The battery is like 550 or 650cca. Can't remember but it's just a 50hp motor so it shouldn't need much juice.<br /><br />Never thought about the starter. I figured if it turned over the starter was OK. I'll have the boat repair guy look at it.<br /><br />Thanks for your help!

 

[Navigator]

Re: Tohatsu M50D - fresh battery won't spin fast

Bertschb,<br />I had the same problem a few years back; replaced the connectors, but the battery couldn't turn the engine fast enough to get it to start easily.<br /><br />You said the battery wires came with the engine. These 10 year old wires are probably your problem. You can get corrosion inside the battery wires underneath the casing which blocks the flow of amps getting to the starter. Replacing the cables is the only fix. On an Ohm Meter, you still get a positive connection reading, but when you try to push heavy amps through it, it bottlenecks.<br />I replaced mine and the starter instantly came back to life.<br /><br />A quick way to check is to unhook the battery wires from the connections at the engine and hook a jumper cable to the posts. (make sure you dont short anything in the process) hook the jumper cable directly to the battery and try your starter. If you notice an increase in speed in the starter RPM's then you've identified the problem.<br /><br />Nav

 

[bertschb]

Re: Tohatsu M50D - fresh battery won't spin fast

I checked the ground and hot wire connections on the motor and they look pristine. This motor really does look brand new in most places (under the cowling).<br /><br />What it does now is spin real slow for about 3-4 seconds then starts cranking fast. If I kill the motor and wait a couple minutes then start it again it cranks fast and fires instantly. It always starts, it just spins slow on the first attempt of a cold start.<br /><br />Your theory about the wires may be a good one. I did trim off a couple inches from the end of the cables when I first got the boat because they looked kind of grungy. The cables are really long so maybe I'll cut another few inches off and see if that improves things. If not, I'll mention the cables to the repair guy next week.

 

[TOHATSU GURU]

Re: Tohatsu M50D - fresh battery won't spin fast

In addition to what everyone else has said, it could be a bad atarter or the rings sticking to the cylinder walls or a bad bearing in the crank. Usually its just resistance in the battery cables due to corrosion....which is what Navigator was refering to. Moisture gets into the cable(there may be no visual sign of corrosion) and you wind up with low voltage to the starter.

 

[bertschb]

Re: Tohatsu M50D - fresh battery won't spin fast

I think it was the cables. I trimmed about 12" off the ends and now it spins and starts much quicker. Thanks for all your help guys!

 

[igness]

Re: Tohatsu M50D - fresh battery won't spin fast

Some times bad brushes in the starter will cause this. But good luck trying to get them to sell you the brushes (if thats the problem), they like selling you new ones, or rebuilding them theirselves.

 

[bertschb]

Re: Tohatsu M50D - fresh battery won't spin fast

Dang! I thought I had this licked. I started it cold yesterday and it spun REALLY slow again for 3-4 seconds. Then it started spinning fast and the motor started up. Every subsequent start was instant even though the motor had only run for maybe one minute.<br /><br />To the shop to check all the stuff you guys mentioned....

 

[bertschb]

Re: Tohatsu M50D - fresh battery won't spin fast

Problem solved!<br /><br />It was a bad battery cable. I replaced the hot battery cable and it spins like a banshee now.<br /><br />Thanks for the help!