1.8 Gurus....

[Englewoodcowboy]

My twins are not acting the same when it comes to WOT. My Stbd engine will run up to 7500 rpm at WOT and my port will only do 7100 rpm. I have checked and adjusted my throttle cables to make sure I am getting the full sweep of the potentiometers but when running it is only at WOT that I see a difference between the two. Any thoughts?

 

[McMark]

Usually it's the other way around due to pump loading.

Maybe a little oil on one filter.

Maybe spark plug time.

I've noticed some changes from startup to startup in the same day so maybe cycle the ecu with a fresh start and let it boot all the way.

 

[Boat Crazy]

My first come to mind thought is spark plugs.

 

[Englewoodcowboy]

It is almost at the 10 hour mark so plugs will be going in very soon and will see if that helps. I did notice a slight vibration at idle in the motor and thought that it could be plugs as well after checking the obvious things like something in the pump etc. Why would these 4 stroke engines go through plugs so fast? I know I will be replacing them once a year along with the oil etc... just seems a bit odd as I would expect that usage on a 2 stroke but not a 4.

 

[rkluck]

There are several threads on spark plugs and not everyone changes them every year. You do inspect them every year. I used to replace mine every year but now I do it every other year. I did have issues due to spark plugs early on but so far now so good!

 

[MikeyL]

@Englewoodcowboy .......... I would be VERY INTERESTED in hearing your comments about all of this after a plug change.
I think you might help many here. Thanks, Mikey Lulejhian - Lake Oconee, GA

 

[Boat Crazy]

It is almost at the 10 hour mark so plugs will be going in very soon and will see if that helps. I did notice a slight vibration at idle in the motor and thought that it could be plugs as well after checking the obvious things like something in the pump etc. Why would these 4 stroke engines go through plugs so fast? I know I will be replacing them once a year along with the oil etc... just seems a bit odd as I would expect that usage on a 2 stroke but not a 4.

I only change plugs once a year and could probably go two and never any problems, however could just be a bad plug.

 

[Englewoodcowboy]

When I did the plugs on my 192 last year they looked good, I still replaced them because I had them and Yamaha recommends that at the 10 hour break in period. We will know the results very soon. I won't be going out in the boat this weekend but next weekend I will be for sure.

 

[dan144k]

It could also be something with the impellers. One may be lightly damaged.

 

[Englewoodcowboy]

Well my boat is at the dealers for it's first service. I was going to do it myself however when he told me $100 per motor for oil plugs and a thorough check I said he can do it. I have to tell you I am really getting impressed by my local dealer/marina. They are falling on some hard times as the lake he is on is being kept below winter levels (-35' from full pool) due to a dam leak and repair with an uncertain ETA of completion yet they are hanging in strong. I have invited them to join this forum and I hope he does.

One other issue that has popped up twice now is the port engine would crank and not fire. I would cycle the key all the way off once or twice then it would fire right up. This is also the engine I feel the slight vibration in at low RPMS and what I think could all be caused by semi fouled plugs. I am waiting to see what they look like when pulled and f that solves the issue. Other than a few things loose like the bow grab rails and a pesky tower hinge bolt that keeps coming loose all is good!

 

[subysti]

The shop manual says to check the plugs at 10 hours not replace. The plugs don't need to get replaced until 50 hours. My Yamaha sled has the 998cc 4 stroke engine, it's a 2007 and I've never had to replace the plugs. You may want to ask the dealer if they are in fact replacing the plugs or just checking.

 

[Englewoodcowboy]

@subysti I will certainly find out. Either way they are going to plug in the diagnostics to see what it is I am talking about with the vibration at idle and low rpms on that motor and the no fire issue. Hoping the computer has stored some codes so it makes it easier to resolve. Other than that it runs like a scalded dog and I couldn't be happier.

 

[smthng]

One other issue that has popped up twice now is the port engine would crank and not fire. I would cycle the key all the way off once or twice then it would fire right up. This is also the engine I feel the slight vibration in at low RPMS and what I think could all be caused by semi fouled plugs. I am waiting to see what they look like when pulled and f that solves the issue. Other than a few things loose like the bow grab rails and a pesky tower hinge bolt that keeps coming loose all is good!

Any time I hear about any intermittent engine issues, I think about the safety switches at the rear hatch. On my LX210, it would happen any time I cut the throttles suddenly... One engine would die. Most of the time it would fire right back up, but sometimes it took two or three attempts. It turned out that the water would wash over the swim deck and that was enough to move the hatch just a hair and cut the safety. Took me forever to figure it out. You could be getting the same symptoms just from vibration when starting or idling the engine. It's real easy for one to get a little loose and back out to where it's one barely doing it's job. A little vibration and you get a cut-out or not firing. It's an easy check to tape a nickel to the hatch for a day to rule it out.

 

[Englewoodcowboy]

I will check that out when I get the boat back if they find nothing. I have ben holding off on it till I add a rear bilge pump and pull the tray out to do it, I was going to check the switch adjustment then. A nickel and some gorilla tape will resolve it for now and I will test. The first time it happened to me I did kill the engines by opening the hatch to get out the tube rope and it happened and I thought of the previous threads and opened and closed the hatch etc and cycled the ignition and no problems the rest of the day. The second time it happened we had not opened the hatch but had been swimming and being that we walk across that hatch could be the issue, so I am agreeing that it could simply be that switch needs a little adjusting because any other time when it is running, it runs like a fine Yamaha should.