Starboard engine a no show... not sure why

[jetboater4life]

Went out for some wakeboarding and wakesurfing on Tuesday. Fired up each engine for a few seconds in my driveway before the 15min pull to the lake. Got to the lake, loaded up, checked everything off my list, and launched. Port engine fires right up, starboard engine just cranks over and over and over but does not fire up. WTF??? So I figure it's probably some fouled up plugs. While hooked to the dock I got my tools out and low and behold I had forgotten to put my spare plugs back in the boat.....

So I pulled plug number 3 on the starboard side but it didn't seem bad at all (pictures below). I put it back in and still no fire up. Checked off everything on the turns over but doesn't start list and couldn't find the problem. So I loaded it back up and filled the tank up on the way home. Tried starting after the tank was full and still nothing. Port engine fires right up. It was half full before filling just as the gauge said so off to home I went. Didn't have a chance to look at it that night or yesterday but today I hopped in both engines fire right up. WTF??? again. Were the plugs fouled maybe? I didn't smell any gas on the plug I pulled out on the water.

So I got to doing something I had intended on doing after I blew off my fogging oil and that is changing all my plugs. The boat had run just fine the handful of times I've been out so it wasn't a priority until now I guess. I changed all eight plugs tonight and the engines seemed to fire up a little quicker when I turned it over. Sooooo do you guys think the starboard engines plugs were fouled up? How would this have happened? Here is a picture of my setup for changing along with starboard plugs followed by port plugs. Starboard plugs: closest plug is on the left. Port Plugs closest plug is on the right.


I'll note that the reason I have two plug wrenches is because one is magnetic and the other just has a rubber boot inside that doesn't work well anymore. I used the T handle to break the plugs loose and to do the final tighten. I don't use the ratchet with the magnetic one (however I add the extra extension) and can quickly spin the plug out or in until is finger tight. The dielectric grease is for the plug boot. I noticed some rust inside my plug boots and think the dielectric grease will aid the connection and keep moisture out.

 

[jetboater4life]

I'm a little worried that I'm going to do the launch and starboard engine is going to turn over and play dead on me again .....

 

[Gym]

I had the same thing happen to me @jetboater4life on our maiden trip when the boat was "new to me". The engine would start in the driveway but not when launched. It turned out to be a broken center electrode. When I held the plug upside down to view the gap it looked fine. When I turned it right side up the gap closed up completely. If I shook the plug up and down it would rattle. I think it was thermal shock. Your's may not be completely broken but may be fractured. Thanks to this board I knew exactly what to look for.

 

[Ronnie]

A loose but closed clean out plug hatch caused one engine to fire and the other not to for me in the past. I found that one of the safety switches under the clean out hatch had come loose and sunk a little deeper into the tray. Also the latch cam on that side was a little low so it would lock that side of the hatch down but still allowed some play between the hatch and the safety. It was an easy fix, just tighten up the nut holding the safety switch in place an raise the cam on the latch a little but it was hard to discover. It wasn't until someone was standing on the hatch that I realized what the problem was.

 

[Boat Crazy]

Strange, but the left plug in the second picture looks like a fouled plug but you say that is the non trouble engine.

 

[jetboater4life]

Strange, but the left plug in the second picture looks like a fouled plug but you say that is the non trouble engine.

@Boat Crazy Correct I noticed that too. That is from the port engine and ran flawless. It was noticeably "wet" compared to the others.

 

[jetboater4life]

A loose but closed clean out plug hatch caused one engine to fire and the other not to for me in the past. I found that one of the safety switches under the clean out hatch had come loose and sunk a little deeper into the tray. Also the latch cam on that side was a little low so it would lock that side of the hatch down but still allowed some play between the hatch and the safety. It was an easy fix, just tighten up the nut holding the safety switch in place an raise the cam on the latch a little but it was hard to discover. It wasn't until someone was standing on the hatch that I realized what the problem was.

@Ronnie
I was going off the no start list https://jetboaters.net/threads/engi...engine-codes-and-battery-voltage-states.1835/
and according to it, the engine won't even turn over if the cleanout switches are not fully pressed in. My starboard engine was turning over just fine so I don't think that was the problem.

 

[jetboater4life]

I had the same thing happen to me @jetboater4life on our maiden trip when the boat was "new to me". The engine would start in the driveway but not when launched. It turned out to be a broken center electrode. When I held the plug upside down to view the gap it looked fine. When I turned it right side up the gap closed up completely. If I shook the plug up and down it would rattle. I think it was thermal shock. Your's may not be completely broken but may be fractured. Thanks to this board I knew exactly what to look for.

@Gym This is very interesting as I had not heard of this sort of thing. I should have looked the plugs over more carefully, because now they are jumbled together at the bottom of my garbage can. While lining them up for the photo I didn't notice any issue. My other thought is I could possibly have a loose connection at the lanyard. Would it be possible for one engine to start but the other not with the lanyard or are they both a go or no-go.

 

[itsdgm]

@Ronnie
I was going off the no start list https://jetboaters.net/threads/engi...engine-codes-and-battery-voltage-states.1835/
and according to it, the engine won't even turn over if the cleanout switches are not fully pressed in. My starboard engine was turning over just fine so I don't think that was the problem.

It could easily be the lanyard switch or the cleanout switch. Keep in mind that either of those two switches (lanyard or cleanout) are controlling two circuits with a single plunger. So it's very possible that corrosion or alignment in one circuit could be off while the other circuit is fine. If the problem persists, try exercising the plunger a few times, if the problem is still there, swap the plugs on the switch and the problem should transfer to the other engine. If the problem still exists, you can rule out the switch. Also, your issue could be the ignition switch as well. Same diagnosis, exercise the switch a few times, then swap plugs to see if the symptom jumps to the other engine.

Hopefully you're all set anyway, good luck, have fun.

 

[jetboater4life]

@itsdgm The cleanout switch prevents the engine from turning over and the engine was turning over so I don't think it is cleanout switch related. Correct me if I'm wrong. If I am wrong then the troubleshooting list needs to be updated.

 

[txav8r]

@jetboater4life , the lanyard has two switches under it, one for either engine, and it interrupts the ignition only, the starter will still turn. And the lanyard switches do wear out if used frequently to kill the engines, it is like a thickness gauge except being plastic, so it can be too thin to fully separate the lanyard plunger to hold it open and keep both switch circuits happy. I am not saying that is what it is, but it is a player in the flow of things.

That MR-1 is touchy with spark plugs as we all know. It won't like a less than factory tolerance gap, doesn't run well if fouled or following heavy fogging. One thing that is common however, is when the engine is hard to start or runs poorly, a spark plug change is often the solution. Enj0y, those CR9EBs are CHEAP compared to the LFR6A. And speaking of, I have been on the run around for my plugs today. I was sold the LFR6A-11 with the boat as supplies I purchased, and I asked for LFR6A. I didn't notice until I got home. But after reading and hearing differing versions of what is an ever changing corruption of the facts, I called NGK. Turns out that the only difference between them is the gap, which I had already concluded. But what I suspected but didn't know, is that the electrode arm is longer on the -11, and gapping down .009 to be in factory specs on the high side, will put what NGK considers excess strain on the weld. Their tech, Chase, told me that the weld could easily break and that much bend could also move much easier as bending the arm that far would more than likely change under load when the metal heats up. Interesting what you find out.

Keep us posted on how your starboard engine runs after the plug swap, but my money is on full recovery on that engine!

 

[Steelerville]

Everyone probably knows this but an indicator that you plugs are burning properly is they will have a nice brownish tint to them. However some are fogging their motors so those plugs may not look like that until the oil is burnt off of them. If you weren't fogging your motor I would say the plugs above are running pretty rich, especially the one that is wet. That plug is not firing. I don't fog my motors.

 

[txav8r]

Just to help clarify, it is my understanding, that only the ignition circuit (both engines, 2 switches) is disabled by the kill switch lanyard, not the starter circuit. This is different than the clean out tray kill switches. There are actually 4 switches in that system, a single ignition and a single starter interrupter to each engine. The engine will still turn if the lanyard is pulled, it just won't fire. It will neither turn, nor fire if the clean out tray is open. That said, you do have two separate switches to each engine in the clean out tray, and a failed circuit on either switch could give different results. I would have to go back and look, but the intent is to stop rotation, and that is so important, Yamaha kills both the ignition and starter with the clean out switches. What I don't know is what happens when a single switch on one engine fails...there may be a failsafe, meaning the failed switch fails open.

 

[txav8r]

Yamaha recommends fogging now on all of these motors, but many still don't. There is a tech bulletin out that is especially important to read and understand if you boat in salt water or in a salt air environment. It is so important, Yamaha is recommending fogging more often than just for winterization. Here is the tech bulletin if you care to read it.



I put thumbnails only, because this has been posted many times and many won't care to see it again.

 

[itsdgm]

@itsdgm The cleanout switch prevents the engine from turning over and the engine was turning over so I don't think it is cleanout switch related. Correct me if I'm wrong. If I am wrong then the troubleshooting list needs to be updated.

The way I understand it is that the cleanout switch prevents it from turning over and kills the ignition. Two circuits. If the engine is running and the lid is open, the ignition shuts off. Therefore it also makes sense that if the switch goes bad, it's possible that the engine would turn over but won't fire.

 

[jetboater4life]

The way I understand it is that the cleanout switch prevents it from turning over and kills the ignition. Two circuits. If the engine is running and the lid is open, the ignition shuts off. Therefore it also makes sense that if the switch goes bad, it's possible that the engine would turn over but won't fire.

Ok I understand now. I didn't realize that there were two separate circuits here for each engine as @txav8r also mentions. I just assumed that if the cleanout switch was failing the engine wouldn't turn over which was not my scenario. Sounds like I should update the trouble shooting list.

 

[MOA_Chaser]

I researched the cleanout hatch thing, and from "the other site" there was at least one instance CONFIRMED where an out-of-adjustment hatch switch caused the engine to turn over but not start. Just because it won't turn over when fully extended doesn't mean it won't have a different behavior when almost closed.

 

[jetboater4life]

The problem with mine is that it is intermittent so debugging will require another failure and then the swapping of connections.

 

[itsdgm]

The problem with mine is that it is intermittent so debugging will require another failure and then the swapping of connections.

You can swap the connections and leave them swapped. If the problem ever reappears (but jumps to the other engine) intermittent or not, you'll know that it's one of the variables that was changed. It would be hard to live with the ignition switches backwards, so I'd probably leave those as is for now. But with the clean out and lanyard switches there wouldn't be any noticeable difference in operation.

 

[MOA_Chaser]

The problem with mine is that it is intermittent so debugging will require another failure and then the swapping of connections.

I'm in the same boat. Everything worked PERFECT since I got it a few years ago, now this year all of a sudden I have a stubborn port engine. And there's a few people with the same issue.

Makes me kind of wonder if there's some gas formulation change that we don't know about, and one of the engines is touchy enough that we have problems with it but the other is fine. Completely random whether my port engine will start right up or not.