Limped home on one motor. Why?

[Marvin willis]

Went out today and everything was perfect as usual. After anchoring for 4 hrs with 2-3 foot waves we decided to head back. I had my dad drive while u was putting up the anchor and when I got at the wheel less than a min later I realized he only started one motor. When I tried it would turn over fast but wouldn't start. Tried several times. After I got it our of the water it fired up immediately. Runs perfect now. Why?

 

[Marvin willis]

Only other thing is I was working with my dad on his driving earlier so we did a lot of driving without plaining out. Don't know if that will cause a plug to foul.

 

[tdogg]

How fast did you run with only one motor running? If it was over no wake speed then you may have pumped water into the engine that was off. Did you continue running with one motor off? How far did you go?

When you run on one motor you either have to go only at no wake speed or have shut off valves installed on the cooling lines to the motor. I carry a set of vise grips that I can clamp on the cooling lines in the event of an engine failure.

You need to go check your oil and see if it looks milky. If so I would run to the store and pick up two 5qt jugs of oil and start changing it immediately. Do as many complete oil changes as possible on that engine till the oil looks clean and fresh. You may want to pull the drain plug on the bottom of the oil cooler to get the complete drain. It makes a mess but if you have water in the engine it could be the death of that motor.

Hopefully you don't find milky oil.

Best of luck,
Toby

 

[Scottintexas]

these inconsistent problems are the hardest to solve, the mr1's do seem finicky with fouled plugs possibly because of extended idling but I wouldn't think a few hours would be a problem.

The only switch problem would be the lanyard and if the other one started it kind of rules it out % percentage wise.

I would tell you to chalk it up to an anomaly, test it a few more times at home and if not see if it happens again on the water to better help isolate it.

How old is your fuel? did you use any stabilizer over the winter?

 

[2nazt]

I heard a lot of people have issues starting after sitting. Did you run blowers? Open hatch to engines? I've just heard this a few times but people let the blowers run and then they start due to heat build up.

 

[Marvin willis]

I have shut off valves. Oil is fine. Yes I use sable before winterizing and I used Lucas before filling up today. Tried to buy new plug but nobody had any in stock. But this is my third time out these plugs. We were running 6000 rpms all morning not idle. Not completely plained out. I didn't use the blower

 

[buckbuck]

Just exercise your lanyard switch and I would venture your problem goes away.

 

[Marvin willis]

Exercise?

 

[Murf'n'surf]

Exercise?

Plug, unplug, plug, unplug, etc.

 

[Andy S]

The lanyard switch has dual contacts, each motor has its own contact so the lanyard switch can impact one motor and not the other.

 

[bronze_10]

What about the kill switch under the clean out tray lid.... the switch my be bad for that engine and when loading it was juggled back into place

 

[Marvin willis]

The one under the clean out tray won't let the starter engage. Lanyard will

 

[itsdgm]

The one under the clean out tray won't let the starter engage. Lanyard will

In theory yes. But each cleanout switch has two circuits. One cuts ignition and the other cuts the starter. So if water got inside the switch or one of the two circuits went bad, it's possible that it would crank and not fire. Not really a big chance, but still a chance. Easiest way to eliminate this as a cause is to swap switches from one harness to the other and see if the problem switches to the other engine.

Good luck with your diagnose, hopefully it's an easy fix.

Ps, imho, you're more than likely ok if you ran on one engine less than a minute.

 

[Marvin willis]

It was a pita to get back. The coast guard was waiting at the dock to check every boat so I was in line for at least 30 mins. Ps cobra fins help you steer better on one motor too.

 

[Marvin willis]

All is well today. Had a vibration when I started out after sitting a while at the beach. Pulled the clean out plugs and I didn't find anything but worked fine afterwards

 

[Jgorm]

How fast did you run with only one motor running? If it was over no wake speed then you may have pumped water into the engine that was off. Did you continue running with one motor off? How far did you go?

When you run on one motor you either have to go only at no wake speed or have shut off valves installed on the cooling lines to the motor. I carry a set of vise grips that I can clamp on the cooling lines in the event of an engine failure.

You need to go check your oil and see if it looks milky. If so I would run to the store and pick up two 5qt jugs of oil and start changing it immediately. Do as many complete oil changes as possible on that engine till the oil looks clean and fresh. You may want to pull the drain plug on the bottom of the oil cooler to get the complete drain. It makes a mess but if you have water in the engine it could be the death of that motor.

Hopefully you don't find milky oil.

Best of luck,
Toby

Hi Toby,
I'm brand new to Yamaha, but not new to engines. How does water get in the non running engine's oil?
Thanks,
Joe

 

[Scottintexas]

Joe,
our engines are cooled with lake water, if you turn one off or are being towed water can be forced through the cooling system eventually to the exhaust valves into the engine (which normally have exhaust pressure pushing water out while their running)

Check out this video from one of our members about the cooling system,
https://jetboaters.net/faq/how-does-the-cooling-water-flow-in-my-yamaha.101/

 

[Bruce]

Hi Toby,
I'm brand new to Yamaha, but not new to engines. How does water get in the non running engine's oil?
Thanks,
Joe

The cooling water intake is at the back of the jet pump. If the boat has sufficient forward movement water will flow through the cooling system despite the engine being off.

 

[swatski]

Hi Toby,
I'm brand new to Yamaha, but not new to engines. How does water get in the non running engine's oil?
Thanks,
Joe

It is also a good idea to leave the "OFF" engine throttle pushed forward -- to open the reverse gate and alleviate some of the pressure of water backing up into the jet nozzle.

--

 

[Jgorm]

Thanks guys. I forgot the water is injected into the exhaust manifold close to the heads. Makes sense, and I'm glad I found out now!