Tohatsu 40C Problems

[CKboater]

I recently bought a used Tohatsu 40C and at first thought the engine was no good. I brought it into a mechanic/Nissan dealer who said that the spark and compression were excellent and he thought it was worth some fixing up. He got her running real nice except that I noticed some surging underway. The boat would speed up and slow down occasionally, sort of like it had a will of it’s own. Coming from a problem Evinrude I was willing to live with this oddity.

On Friday, however, I took her out on a first longer run. We were going maybe fifteen minutes at ¾ throttle when it seemed to get sluggish and soon came off the plane despite my going to full throttle. There seemed also to be some white smoke or steam that I hadn’t noticed before though cooling water was clearly pumping. We turned around and headed back at a slower speed and after awhile she was able to get back on a plane and got us home.

Today I took her out again and after just a short time she fell off a plane and lost power. I turned around again and started back and after a little while tried to power her up again but this time, after briefly speeding up, she just died. She would start again but now stalls whenever I try to put it in gear. I noticed also that the fuel hose bulb keeps getting soft like she’s maybe not drawing fuel and thought “fuel pump” but she starts and the fast idle lever seems able to speed her up though she won’t run at idle speed anymore and, as I noted, stalls when put in gear.

Any suggestions as to what this might be would be appreciated. I’ll probably bring her back to the mechanic but I’m not sure how much more I should put into what may be a sick engine. Recently, my luck with outboards couldn't be any worse.

Bill

 

[John_S]

Re: Tohatsu 40C Problems

I you have another gas tank and hose, just swap and try that. Doesn't help, move to carb and fuel pump. Both are easy to do, and would be recommended after buying an unknown condition motor.

You are also lucky, Elvin is in Tampa. He should be able to help you out. He will have all parts and manuals, and service if you need it.

 

[TOHATSU GURU]

Re: Tohatsu 40C Problems

Bill,

Surging can be either a fuel or ignition problem, but smoke or steam is a dead give away of a mechanical problem(Barring a cooling issue). What shop had it?

 

[ArtB]

Re: Tohatsu 40C Problems

I you have another gas tank and hose, just swap and try that. Doesn't help, move to carb and fuel pump. Both are easy to do, and would be recommended after buying an unknown condition motor.

You are also lucky, Elvin is in Tampa. He should be able to help you out. He will have all parts and manuals, and service if you need it.

I agree with all of this. My Nissan 40C was acting the same way and Elvin talked me through it. It turned out to be a bad fuel line connection at the tank. Good luck!

 

[CKboater]

Re: Tohatsu 40C Problems

I had her serviced at Northeast Marine in St. Petersburg.

To make matters more complicated, I fooled with it some yesterday evening to increase the idle slightly so it wouldn't stall all the time. Today I took it out for an hour and it ran fairly well.???? I still feel the occasional increase in speed (as if someone is smoothly giving her throttle) and then it drops back to the previous speed. I was wary of really pushing it hard not wanting to do that on a Sunday when the towboat services are so busy.

Some other thoughts: The carb was cleaned in the shop a few weeks ago. This trouble started after I used a second fuel tank. I put in clean fuel but wonder if maybe there was water or contamination in the hose. I'm back to the original tank now.

My friend dismisses the smoke we saw as normal but I'm not sure overheating isn't an issue.

I'm not sure what to do next other than go out again with my tow boat card, VHF radio, cell phone and some cold drinks and try pushing it. I'm thinking that bringing it to the shop again won't help if this only occurs under load.

Bill

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[TOHATSU GURU]

Re: Tohatsu 40C Problems

It could indeed be a fuel isue, but white smoke or steam would not be normal under any condition. Keep an eye on it.

 

[CKboater]

Re: Tohatsu 40C Problems

I took her out again today and she started and ran well for about fifteen minutes. Then it got that sluggish feel again and came off a plane. I reduced throttle and tried going slow but she stalled with much clunking and definite white steam or smoke coming from the engine.

It seems to be related to heat buildup so I'm thinking the water pump is not doing all it should though I do see a slow stream/trickle of water coming out the pee hole. You may recall I had much trouble getting water to pump out this engine when I was using cups and had it on a lift. I have to actually get the water started with the boat in the water and then lift it out with the cups attached and fresh water running. Of course I'm just guessing so I'd love to hear some other ideas and suggestions.

The good news is that after a short while I was able to start it again and run it at slow speed to get myself home without a tow.

Thanks.

Bill

 

[TOHATSU GURU]

Re: Tohatsu 40C Problems

Anything in the cooling system to a cracked engine block.

 

[CKboater]

Re: Tohatsu 40C Problems

Elvin,

Is this the sort of thing they should be able to pick up in the shop or am I better off having a mechanic come to the boat?

A cracked block certainly doesn't sound good so I hope thats an outside chance.

Bill

 

[TOHATSU GURU]

Re: Tohatsu 40C Problems

I'd take it in to them. Anything that could be the cause would show up on muffs. Water testing is almost always a waste of time and would just run up your bill with a service call. Also, techs hate doing house calls and will always pad the bill Based on your previous posts:

1)They need to do a compression check. The headgasket wil almost certainly need to be replaced even if the block is undamaged.

2) Drop the lower unit and replace the water pump. Then they will need to blow air or force water up through the tube to check for an obstruction before putting the unit back on.

 

[CKboater]

Re: Tohatsu 40C Problems

Thanks Elvin. I'll try to get it into them next week. I'm hoping that this is a cooling problem. The compression was checked less than a month ago and was excellent and I ran her very moderately up to this current trouble.

 

[CKboater]

Re: Tohatsu 40C Problems

Just to let everyone know...... I got the boat back from the shop and the Water pump housing bottom plate was deformed and the inside of the pump body was encrusted with salt. Thus the engine was overheating due to a lack of sufficient cooling flow. I got her back the other day and she seems to be running fine. This would also explain the difficulty I had getting it to spit water on muffs.

Thanks for the suggestions.

 

[John_S]

Re: Tohatsu 40C Problems

Thanks for the post. After the last couple, it sounded very ominous.