new to me Tohatsu 9.8 problems: oily, smoky, finally runs but won't idle...

[woodrat]

Just bought an older Duroboat the other day that came with a barely used 2009 Tohatsu 9.8 on it. Electric start even, wow!

Anyway, got a trailer under the skiff last night and took it down to the local launch this morning to check things out, and it didn't go so well. First it didn't want to turn over, either with electric or pull cord. Then it finally would, but was blowing oil all over the water. Would start, run briefly and die, smoke everywhere. "

Took the plugs out and they were oily, so cleaned them, checked with my finger for compression and it seems adequate and even between the two. Finally after a lot of fooling around got it to start and run, but with the throttle just above "restart", it was pretty high revs, and if I tried to bring it down at all, even a tiny bit, it would die rather than idle.

I finally packed it in without every leaving the boat ramp and brought it back home. I'm going to stick my old Evinrude 15 on there for now, but it would be nice to figure out if the Tohatsu is actually OK, or something drastic is wrong.

Oh, also looks like oil is overfilled, so I need to deal with that no matter what. Drain and replace, I guess. It's sparkling clean as is the rest of the engine. It doesn't look like it's been used much at all.

Thanks in advance!

 

[pvanv]

Probably an MFS9.8A3. Year is irrelevant. Only holds about 3/4 quart of oil. Yes, get the level down between the 2 marks on the dipstick. After that, if you can't get idle, it likely needs the carb disassembled and Properly cleaned.

 

[woodrat]

Yes, that's it. I drained the oil and replaced it with the right amount. It was all the way full to the top of the measuring hole. I think someone just dumped a whole quart in there.

Tried running it on the cuffs at home, and it's doing the same thing. Thinking maybe there's a piece of crud in the low speed jet or something...

On a separate note, is this motor likely to get this boat up on a decent plane, or is it a bit too small? That's what I was hoping to get a test of yesterday. I love my Evinrude 15 and that will definitely fit this boat well, but it's also noisy, loud and doesn't charge a battery, either... lol.

Thanks!

 

[MattFL]

Agreed with the above, disassemble the carb and make it surgically clean. Use an ultrasonic cleaner if you have access to one, put air and cleaner through every hole, especially the tiny ones. Wear goggles.

 

[woodrat]

I did take the bowl off and the jets out and cleaned with acetone, but didn't have the compressor handy, and don't have a carb kit for this yet, so didn't do super deep. The bowl had a lot of crud.

Put it back together and it started easier but still had the same won't idle problem. I took it off the boat and put it in the barn to work on later. I think I should probably replace all fuel lines and go through the fuel pump, too, based on what the carb bowl looked like.

Guy said this motor only had about 20 hours on it, and it's so clean I think he might be right. But I think I need a carb kit and fuel pump kit to go any further with it.

 

[pvanv]

Those pumps are very reliable. I would just flush the heck out of it. Probably still need a good carb cleaning. Likely don't need a kit.

 

[km1125]

I agree with Paul, you don't likely need a kit and you just need some good cleaning. You can clean the pump too, if there was some junk in the bowl. Just be careful as you disassemble and you can re-use all the parts after they've been cleaned.

As to your question on planing, I think it would all depend on load. Should be easy to plane a flat-bottom boat with that motor, especially if you can play with weight distribution inside the boat. Load it too much though, and all bets are off.