Trouble with my Tohatsu 9.8 four stroke

[ngt]

I have trouble starting it. It's a pull start. I took it out in the driveway today and it took a good 7-8 pulls before it started. Once going, when I'm out on the river, it usually stalls out at the dock a few times and I have to put it into gear at a bit of a higher idle, causing the boat to jerk on take off....once we get going for a second, it's perfect and I could go as low as I can in or out of gear and be fine. When I'm out at a spot, for a long time, it sometimes takes a couple pulls to get it going again. If I am only there for an hour or so, it starts first pull. Today in the driveway it didn't stall out at all.

The only differences I can think of is that the driveway has the gas tank and motor leaning at opposite angles and when I was at the river, I had the valve on the gas tank that lets in air all of the way open. I'm wondering if too much air gets through and not enough cas and that's why it stalls out? At home today, I only opened it a little bit. How far do you open that valve when starting up your boat? or do you?

Either way, it still should be starting up faster than 7-8 pulls. It's 2008.

Ideas? or things I could check? Nothing with oil or seals with water as I've checked it and the oil looks perfect. No white or baby poop colors.


thanks

 

[fishndirk]

Re: Trouble with my Tohatsu 9.8 four stroke

Dont fret. I have a 2010 20 hp tohatsu 4 stroke. I think your motor is fine. Mine starts 2 pulls normally (one to warm up). But it has started with 4-5 pulls frequently. Its not a precision system, you cant expect much. One time I filled the gas tank too much and drove through hot weather and the gas expanded and it flooded the carb. Took me forever to start it. Disconnected the fuel line to start it then re-connected it once started. I think your motors fine from what is sounds. Maybe change the spark plugs or wires if anything if you havent done that already.

 

[pvanv]

Re: Trouble with my Tohatsu 9.8 four stroke

You didn't mention model. Year is irrelevant. I'm assuming you have an MFS9.8A3, right? It should start by the second pull. So there is a problem, either with operator technique or the motor. When did this problem start? When was the motor last serviced? What is the oil level on the dipstick? How long do you warm up the motor before trying to go into gear?

The vent on the tank will not cause carb flooding. It should be open when running, or else the tank will start collapsing as the fuel pump draws a suction, and the motor will stall. However, as was noted, heat-related fuel expansion can flood the carb -- so don't leave the fuel line connected when not running. Of course, at the end of the day, the motor should always be run without the fuel line connected, until it stalls. That runs the fuel out of the carb, so it won't varnish as it evaporates.

 

[TOHATSU GURU]

Re: Trouble with my Tohatsu 9.8 four stroke

It should start on the first pull every time. The second pull on a bad day. The third pull if you live a sinful life. Anything over that indicates a problem. Like Paul said, that can be with the operator, the maintenance of the engine or an actual mechanical malfunction. Since it is a 2008 it should go into a dealer for a determination.

 

[ngt]

Re: Trouble with my Tohatsu 9.8 four stroke

You didn't mention model. Year is irrelevant. I'm assuming you have an MFS9.8A3, right?

yes

It should start by the second pull. So there is a problem, either with operator technique or the motor. When did this problem start?

2nd time I took it out. Only been out 5-6 times in the last year. I've only had it for a year. I know very little about boat motors or boats in general and I am leaning towards an "operator technique problem"

When was the motor last serviced?

when I bought it, mid last summer

What is the oil level on the dipstick?

pulled it out, wiped it off, stuck it back in, pulled it back out and the oil level is all of the way to the top "X" on the dip stick

How long do you warm up the motor before trying to go into gear?

4-5 minutes after getting it started where it's not stalling (only seems to stall when I'm at the ramp, not in my driveway as much)

The vent on the tank will not cause carb flooding. It should be open when running, or else the tank will start collapsing as the fuel pump draws a suction, and the motor will stall.

I was more worried about opening it too far and not getting enough fuel pumped in to get the motor going. I thought maybe it was stalling from lack of fuel.


However, as was noted, heat-related fuel expansion can flood the carb -- so don't leave the fuel line connected when not running.

I've always kept the fuel line on while the boat is in my garage, which can get very hot in the summer. I just went out and disconnected it and will not leave it on again. Think that could be the cause?

Of course, at the end of the day, the motor should always be run without the fuel line connected, until it stalls. That runs the fuel out of the carb, so it won't varnish as it evaporates.

I was told that was a bad thing to do. I always flush it with fresh water when I get home but I've never let it run out. I don't remember why people said this was a bad idea, but I was told it was. You're saying I need to do this every time? Could that be the problem? I bought some STA-BIL but haven't used it yet

thanks for your time and help!!

 

[TOHATSU GURU]

Re: Trouble with my Tohatsu 9.8 four stroke

"The third pull if you live a sinful life"

Not running the engine out of gas is sinful.

 

[ngt]

Re: Trouble with my Tohatsu 9.8 four stroke

"The third pull if you live a sinful life"

Not running the engine out of gas is sinful.

So I should be doing that. OK. I'll do it from now on. Could that cause this issue?

Would running the STA-BIL in there help this issue if that's the cause of it?

Any other thoughts or advice based on the post above?

Going to a dealer at $90 per hour isn't really an option at this moment with my wife out of work and a baby on the way.

thanks!

 

[TOHATSU GURU]

Re: Trouble with my Tohatsu 9.8 four stroke

Yes, no and yes. Not running the fuel out puts you in the position of having your fuel evaporate. As the lighter elements of the fuel go away you get left with a residue that clogs everything up. So, clean the carb, run the fuel out and live a sinless life.

 

[ngt]

Re: Trouble with my Tohatsu 9.8 four stroke

ok. So I just take out the fuel line and keep it running as low as possible until it dies on it's own?

 

[reddogg]

Re: Trouble with my Tohatsu 9.8 four stroke

My dad has one of those (09 model) and had to get it serviced for hard starts, etc... The mechanic said that the tohatsu 4 strokes have really small jets and they get gumed up easy. They did a carb clean on it and it now runs like a top, starts first pull every time.

red

 

[ngt]

Re: Trouble with my Tohatsu 9.8 four stroke

thanks! Do you think that's something the STA-BIL would help or do I have to take it in?

 

[reddogg]

Re: Trouble with my Tohatsu 9.8 four stroke

I'd say you gonna have to take it in. Unless carb cleaning is coverd under your warranty, It cost my dad $100. I run sta-bil in my own stuff, but I see it more as a preventative, not a fix. The mechanic told my dad to keep the fuel filter changed on a regular basis and added a second one to the fuel hose between the tank and the bulb and after flushing it to let the carb run outta gas. It's been running great so far this season.

red

 

[ngt]

Re: Trouble with my Tohatsu 9.8 four stroke

cool. I can do $100, but my shop wants $90 just to see what the issue is. I'd much rather walk in and say "I need my carb cleaned".

Is the fuel filter something I (someone who knows little about motors) could do, or would I ask them to do that when I take it in?

thanks again!

 

[TOHATSU GURU]

Re: Trouble with my Tohatsu 9.8 four stroke

You disconnect the fitting off of the front of the engine and let it run until it wants to die. Then you pull the choke and shove it back in to keep the engine running. You do that over and over until the engine uses up all of the gas in the bowl. Stabil does absolutely nothing to prevent the evaporation. Fuel stabilizers simply keep the fuel from rotting for a few extra months.

 

[reddogg]

Re: Trouble with my Tohatsu 9.8 four stroke

They are inline filters and easy to install. I get the sea-sense brand at wally world. It's a glass filter with a replaceable element and use that one under the cowling. I'd get a hard plastic one for in between the tank and primer bulb, a generic one will work fine. To install them, you cut the fuel line and they slip right in than use zip ties or stainless steel hose clamps to secure them. Make sure you have them oriented in the right direction (most have an arrow showing the direction of fuel flow). There should already be one under the cowling so you can look at how it's installed.

red

 

[ngt]

Re: Trouble with my Tohatsu 9.8 four stroke

cool, thanks! Both of you!

 

[fishndirk]

Re: Trouble with my Tohatsu 9.8 four stroke

I agree with everything said preveously. They are all good tips of advise, but dont freek out when your motor takes a few cranks to get it started, especially a motor of that size. If it takes more than a few than I would start to worry. After all, your arm is not a starter motor. I bought my 20hp Tohatsu brand new out the box and it started first pull for the first few months. Now it starts on the second pull on average. If this makes me a siner than I guess everyone who does'nt live in a perfect world is a siner. This is normal wear and tear. A 3 year old motor just needs a little TLC to keep running for another few years.

 

[pvanv]

Re: Trouble with my Tohatsu 9.8 four stroke

thanks! Do you think that's something the STA-BIL would help or do I have to take it in?

If you have basic mechanical ability, a decent set of metric tools, buy a factory service manual, and want to learn how to do the work, it's possible for an owner to do it himself. About half of my customers do their own. They are what I'd term "mechanically inclined".

Stabilizer will NOT clean the carb. Period.

All EPA-rated and CARB-rated carbureted 4-strokes (of all brands) have very, very lean mixtures. That's achieved by very narrow, higher-velocity passages (unlike the fatter, lower-velocity passages of the older carbs). That makes them more succeptible to varnishing. Plus, the fuel we get today is of lower quality, and leaves more varnishing sooner than the stuff we used to get 30 years ago. Thank your well-intended, but insufficiently-educated lawmakers for that.

 

[pvanv]

Re: Trouble with my Tohatsu 9.8 four stroke

cool. I can do $100, but my shop wants $90 just to see what the issue is. I'd much rather walk in and say "I need my carb cleaned".

Is the fuel filter something I (someone who knows little about motors) could do, or would I ask them to do that when I take it in?

thanks again!

At this point, we have not diagnosed the problem yet. Yes, it is very likely a carb issue. But without a comprehensive diagnosis, it's still a guess. So asking a shop to "clean the carb", while it wouldn't hurt, might not actually solve the problem.

The factory-type inline fuel filter is fine, no, make that excellent, at catching debris in the fuel. If you feel you want more than that, we recommend a 10-micron water-separating filter (they type with the removable canister). But as long as you only use fresh fuel, and keep the tank clean, it's probably not necessary on the 9.8A3.

 

[pvanv]

Re: Trouble with my Tohatsu 9.8 four stroke

Because the motor seems to have more of an issue under load (in the water) than when in free air (on muffs in the driveway), it's probably a situation of too-lean low-speed mixtures, caused by varnishing in the small passages of the carb. Some folks swear that Chevron Techron additive (intended to clean fuel injection), if used in super-extra amounts, may help that problem, in some cases. In our shop,we have not had luck with that technique, but you could try it.

Because of your skill level "(someone who knows little about motors)", I would suggest that you discuss the situation with your local dealer. As long as that motor is healthy, and the correct starting technique is used, it should be running by the second pull. Even if it's 3 years old.