Tohatsu 9.8 making TONS of oil, ran great last time out!

[xjma]

New to me 9.8 Tohatsu 4stroke, ran great first few times out. Have run it in a 55gal drum, never has taken more than 2 pulls to start it, until I tried to take it out today .

Hadn't run it in 2 weeks, left with the stabilized (startron) 93 hooked up out in the back yard. Wasn't turning over when I pulled it. Actually the first few pulls it didn't even pull, felt like it was in gear even in neutral....maybe the shifter was acting up?? After frustration it turned over and puffed smoke (never seen it puff any smoke before) with the throttle open and choke off. Got it started, wasn't running all that well, but running. Stalled when put in gear, got it started again and got it in gear but it wouldn't rev out at full throttle. Then it stalled out and wouldn't restart. Checked plugs despite not having fresh ones on hand (it's a 4 stroke, who needs extra plugs??) and they were soaking wet and black....if it were a 2stroke I would have called them close to being fouled. It definitely needs plugs. Last time out I ran her hard and she loved it, but being by myself left it idling while I got the jeep and trailer....it ran fine getting it on the trailer, which is the last time it was run before today.

So today we gave up and fished from shore Caught a few nice ones and tried to forget about my troubles!

At home I opened the oil fill cap, it smelled of gasoline. Then I opened up the dipstick and gassy oil/oily gas poured out under pressure. I have severely abused many a 2 and 4 stroke motor in my lifetime, and never have I encountered something like this......

Thanx in advance for any help!!

 

[pvanv]

Re: Tohatsu 9.8 making TONS of oil, ran great last time out!

You may have a blown fuel pump diaphragm. Start by diagnosing and correcting the problems you have, and then use good practices to reduce the chances of them happening in the future. Verify the precise model/serial. Tohatsu has an excellent Factory service manual for the 9.8A3, and I recommend that you have one if you are going to do repairs yourself. Order Part# 003-21056-1 for $40.00 from any dealer.

Change the oil. Use 10w-30 FC-W non-synthetic. Fill to 1/2 way on the dipstick.

Install a new pair of NGK DCPR6E plugs.

Remove the fuel pump and test it for leakage. If needed, you can get a new pump, 3H6040007M FUEL PUMP, 4/5/6/8/9.8 4-STR ONLY, for $60.83, from any dealer (including me). Install a new o-ring while you're at it: 3H6074220M O-RING $1.26.

In the future...

Always verify the oil level before going out.

Always, religiously, disconnect the fuel line at the motor at the end of the day (and leave it disconnected), and allow the carb to run out. If you don't, heat/cool cycles can force gas to either flood the carb or blow the gas pump. Likewise, if you leave the carb full, you risk carb varnishing from fuel evaporation over the course of a few days or weeks.

 

[simplystressed]

Re: Tohatsu 9.8 making TONS of oil, ran great last time out!

I had same issue last night during first time out this year. Didn't check level prior to going out could have avoided a sore arm and having to pull and clean the plugs. level was right full when I checked this morning so drained oil and put in fresh to 1/2 full. Running semi synthetic now will be getting regular 10w30 asap.

pvanv is it difficult to remove fuel pump to check for leaks? Where would leaks happen if there is an issue?

Thanks

 

[pvanv]

Re: Tohatsu 9.8 making TONS of oil, ran great last time out!

There are 2 screws that retain the pump to the valve cover. They take a #3 phillips driver. The pump is sealed to the motor with an o-ring. If you detach the pump, and pressurize the fuel system with the primer bulb, a fuel leak would be immediately evident. Unless you have a huge increase in oil, accompanied by the aroma of fuel in the oil, you probably don't have a blown pump diaphragm.

 

[isaksp00]

Re: Tohatsu 9.8 making TONS of oil, ran great last time out!

FWIW, I redid my fuel pump (new diaphragm and oring) on my Honda 8HP and it was not all that hard - a little tricky to get the diaphragm in, but not overly. I did have a shop manual, which is necessary.

 

[xjma]

Re: Tohatsu 9.8 making TONS of oil, ran great last time out!

Pvanv, thanx for the invaluable info! I'm glad it's a simple fix caused by stupid oversight on my part. No more leaving that hose connected or the vent closed!! I think I'll pick up a shop manual so I don't have to ask a question here every time I have a question.

 

[pvanv]

Re: Tohatsu 9.8 making TONS of oil, ran great last time out!

Did the fuel pump test OK?

 

[xjma]

Re: Tohatsu 9.8 making TONS of oil, ran great last time out!

Haven't had a chance to try it yet, hopefully tomorrow after work!