Tohatsu 60 alarm sounds, shuts down

[TomRay]

I have a high-thrust Tohatsu 60 that I bought new in 2014. This was when they merged with Honda, so it's not one of the TLDI two stroke engines. Remove the motor cover and the valve cover says HONDA in big letters, so it's a Tohonda. It's on a pontoon boat.

The other day after cruising for a mile or two, it suddenly "stuttered" a bit and an alarm sounded. None of the lights on the ignition switch panel lit up. It was peeing normally and the temp showed normal numbers on the tachometer display. I shut it down and it started right back up. No alarm. Ran up to speed and got the same result as before, but this time it shut itself down. We headed back to the boat ramp and it would alarm and shut down above about 1200 RPM. There was no steam and the temperature gauge never showed it being hot.

It has clean fuel and oil and was running just fine at all speeds. I'm not sure why it was sounding an alarm and shutting itself down. Any ideas?

 

[pvanv]

You can DL your manual from https://www.tohatsu.com/marine/common/owners_manual/150f3b4385d5095836188da9886847d138f7a8e4.pdf
That should help.

 

[TomRay]

I actually have the service manual for this engine. It says Honda on it because there wasn't one that said Tohatsu yet at the time, but it's the shop manual. Having it doesn't give me the skills and experience to actually use it to figure out this problem, unfortunately.

 

[pvanv]

The green oil light must be on. If off, you are detecting low oil pressure.

 

[TomRay]

The green light appeared to be off when we had the boat out, but I didn't notice until we were almost back at the ramp. Then when I was messing with the boat the next day, I noticed that the green light would glow, but very dim, when I turn on the key. I only noticed because I was in the shade in the pole barn. In full sun, it would not be visible. So I don't really know for sure if it was out or glowing dimly when I had the boat out.

I keep the tach LCD display showing the temperature, but have reset it to show oil pressure. I was thinking about taking it down to the boat ramp and dipping it in just to fire it up and see what the reading is. One problem with this plan is that I don't know what the reading should be.

The other potential problem is that I don't know if the gauge that sends the info to the tach is the same one that triggers the light and alarm. I was talking to a friend yesterday who thinks he has an oil pressure gauge we can hook directly to the engine. I'd like to know if I really have an oil pressure problem, or just a sensor problem, or maybe some other kind of problem.

 

[pvanv]

Low pressure is about 4 psi. Normal is about 40.

 

[TomRay]

Dipped the boat in the water and got a bit more information. The green oil light is dimly lit when the engine is running. I think I recall it being brighter in the past, but it does come on.

The LCD display on the tach says NO DATA when I set it to show oil pressure. It does correctly display engine temperature.

I looked in the shop manual and found the procedure for checking oil pressure with an external gauge. It's kind of internally contradictory. It says to remove the EOP sensor and then run the engine with an external gauge attached in the EOP hole. But step 2 in the EOP removal procedure is to remove the ignition coil assembly. I'm no mechanic but I suspect engine won't run without one of those attached. Maybe they thought reattaching it to run the engine goes without saying?

 

[pvanv]

Yes, you need the ign coil to run.

 

[Sea Rider]

Is it possible to check a correct oil pressure output with ignition coil disabled with just the motor turning for some time ?

Happy Boating​

 

[TomRay]

Do the green light and the oil pressure reading on the tach rely on the same sensor?
Just wondering how the green light knows there's oil pressure and the tach says NO DATA if they rely on the same one.

 

[TomRay]

I ordered a gauge to check the oil pressure. The shop manual says only two things result in a continuous alarm sound: overheating and low oil pressure. The engine was peeing normally, temp showed normal on the tach, no steam, no overheat light, so I'm pretty sure it's not overheating. That leaves oil pressure, and the green light is (dimly) lit. So I suspect it's not oil pressure either, but will check when the gauge arrives.

Lots of the troubleshooting roads in the shop manual lead to "replace the ECM." Starting to wonder if that's in my future?

 

[pvanv]

Check whether oil pressure is OK. You may need a pressure sender.

 

[TomRay]

The oil pressure check procedure involves removal of the EOP switch so I just ordered a new one. If it has to come out, might as well stick a new one in there.

 

[TomRay]

Today I removed the EOP switch and hooked up my new external oil pressure gauge. When I turned the key on, it made some new beeps I hadn't heard before. I started it up and the external gauge showed 60 lbs of oil pressure. No beeping while it ran. Weirdly, the little green light on the ignition switch panel was still dimly lit. How would it know there's oil pressure if the EOP switch is sitting on the stern of the boat?

I removed the external gauge but did not yet install the new EOP switch. The hole was endlessly dripping a bit of oil. The new switch is supposed to get ThreeBond 1215 on the threads before installation. I assume that means installation into threads that are not currently dripping oil?

I left it with a shop towel absorbing the oil. I'll install the new EOP switch later today.

How clean do I have to get those threads anyway? Wipe the oil off or go after it with solvents and Qtips or something?

 

[TomRay]

I put the new switch in and fired it up yesterday afternoon.
The little green light continues to glow dimly.
The oil pressure readout on the tach continues to display NO DATA.
No alarms sounded after the normal beep when the key is turned on.
The engine temp readout on the tach showed it rising at a normal rate. It was peeing normally.
I'm thinking of removing and testing the thermostat but I'm pretty sure it's working because of changing pee stream temps.
I'm as confused as ever. As far as I can tell, the two things that cause a continuous alarm are fine, yet I was getting one and it was shutting down the engine.

 

[pvanv]

Is it still alarming?

 

[TomRay]

Is it still alarming?

No, it hasn't sounded an alarm since that day we had it out. I've run it a couple of times in a barrel now.

When we had it out, it would not sound the alarm immediately, only when RPMs were increased above about 1500 or so. Then the alarm wouldn't shut off, even at idle in neutral, until the engine was shut down. Start it back up, no alarm. Throttle up, alarm and power reduction.

So I don't know for sure if it still has the problem without launching the boat and running it on the water a bit. I suspect it still does, just because I can't see where I did anything to fix it, but I don't know. Maybe I'll take it out tomorrow morning and see what happens.

 

[pvanv]

Roger. Use an IR thermometer to check engine temp.

 

[TomRay]

I don't have one of those but I think my brother still does. He does pottery and his is used to measure whether the kiln is 2000 degrees or so. So maybe doesn't read in the right range? I don't know.

Where do I point it and what should it say?

 

[pvanv]

The block should be about 150F. You can get one at the hardware store or harbor freight.