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Kenny O.
Kenny O., Personal Watercraft Specialist, Kawasaki Jet Ski, Yamaha Wave Runners, Sea Doo Watercraft
Category: Boat
Satisfied Customers: 953
Experience:  Product Specialist Kawasaki Factory Support 24 Years, 8 years National Technical Director IJSBA
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I have twin 135hp engines in a yamaha 2002 lx2000. They both

Customer Question

I have twin 135hp engines in a yamaha 2002 lx2000. They both run well when idling and with throttle open. Vibration of the whole boat is felt way more at idle, not sure if that is ok.
The problem is when opening the throttle, past a certain point (about half throttle) giving more throttle has no effect. Both engines top out between 3600 and 4000 rpm. From what I read, I should be able to pull way more.
Had this problem since last year. My friend rebuilt the carbs on one of the engines, but no inprovement. We replaced the fuel and oil filters, filled up with 93 octane, nothing helped.
Any ideas on what I can do?
Submitted: 5 months ago.
Category: Boat
Expert:  Kenny O. replied 5 months ago.

Hi my name is ***** ***** am I speaking to ?

I have a few questions first

  • Hours currently on the engines ?
  • When was the last time engines were serviced ? and what was replaced ?
  • Salt or fresh water use ?

Thanks

Customer: replied 5 months ago.
Hi kenny. I do not have an hours meter on this boat, so I am not sure.
Port side engine was rebuilt last year. Only replacement were the gaskets. Starter replaced on port engine last week (seemingly unrelated issue). Spark plugs replaced in both engines two weeks ago.
Fresh water use only for me, and I believe was the case for previous owner (that's all we got around here).
Customer: replied 5 months ago.
Port engine carbs were rebuilt on the port engine. The mechanic was suspecting grease on the needle, and rebuilt to see if both needed to be cleaned out. Turned out not to help with not getting high rpms
Expert:  Kenny O. replied 5 months ago.

Well it has a symptoms of a fouled plug without looking at anything else. But here is where I would start.

  • First off, are you planning on doing the work on this ?
  • You are correct you should be seeing for RPM's
  • This is where you need to start, first remove all the spark plugs and mark each one what side engine they came out of and starting with the front plug being #1, middle #2 and to the rear being #3
  • Compression measurement on all cylinders

Don't take for granted that just because the engines were rebuilt recently that everything is OK and that also goes with the spark plugs also. We have mechanical parts here that fail.

If you can pull the spark and then picture the plugs and post them up on here that will help me tremendously ?

Let me know your thoughts ?

Thanks

Customer: replied 5 months ago.
Kenny, it is dark here now. I will pull the plugs tomorrow, number, and take a pic.
I will need to pick up a gauge to do the compression test, should be able to swing it tomorrow as well. I will post my findings
Expert:  Kenny O. replied 5 months ago.

Awesome, if you have a Harbor Freight tool store close, you can pick up an inexpensive one there, bring an old plug so you make sure that you get the correct adaptor.

Customer: replied 5 months ago.
From left to right, #1, #2 and #3 from Port engine
Expert:  Kenny O. replied 5 months ago.

More of the electro, maybe making a hole in cardboard and then more of a picture looking down at the plugs and a little off angle ?

Customer: replied 5 months ago.
Ok, pardon my ignorance. You'd like to see more of the part that sits inside the engine (where the sparking happens )?
Expert:  Kenny O. replied 5 months ago.

that's fine, but I like to see more of the porcelain that encompasses the center electro and the ground strap, its hard to get a picture verses having it your hand and looking at it, #1 (left plug) looks a little wet, however what I can see so far, all cylinders are very rich, should be a nice chocolate brown.

Customer: replied 5 months ago.
Here are some more.
Customer: replied 5 months ago.
a few more standing up. Please let me know if you need to see it at a different angle or light.
Customer: replied 5 months ago.
Did compression test on starboard engine. 82, 82 and 85 on #1, #2, #3
Customer: replied 5 months ago.
I reread my post, just wanted to point out 1 thing I said incorrectly. Spark plugs in starboard engine were not replaced this year; they are from last year. Port side were replaced 3 weeks ago.
I cannot do a compression test on port side for a few days (need to connect back new starter when it gets here)
Customer: replied 5 months ago.
Also looking at the cables running from my ebox to the spark plug, they have a lot of black dust inside where the spark plug is inserted. All cables are dry, except one on the port engine has a bit of moisture. I've had it off for about 4 days now, so it could have dripped into there, not sure, but thought I'm might be worthwhile to mention.
Expert:  Kenny O. replied 5 months ago.

OK maybe I'm not explaining this well, this picture I'm posting is good and the angle is good, what I want to see is the "center" electro inside the spark plug, if you take this picture here its a good angle, take the spark plugs and flip them 180 degrees so I can see the porcelain, the ground strap and the down inside the spark plug

Thanks

Customer: replied 5 months ago.
Do these help? I can take more close up or whatever you need.
Expert:  Kenny O. replied 5 months ago.

Perfect !!!

Expert:  Kenny O. replied 5 months ago.

OK all those plugs look like crap, they are SO rich, it appears that these engines were over "choked" are you running these engines long on choke ?

I see at least three look like they are gas fouled and those are probably not running

Also I would like you to get a compression measurement on all cylinders, when checking the compression make sure that you open the throttle all the way, this will allow more air into the engine an it give you a more truer reading.

Also I'm going to post up a PDF file, I want you to check the spark plugs caps and wires. Give me a little bit on that and also I want you to get 6 new plugs, one of the new plugs has a bent top at the cap ??? that one likely has an issue with the electrode.

Thanks

Customer: replied 5 months ago.
Kenny, I have new spark plugs. I will put these in asap. It will be a few days before I can get compression readings on the port engine. I did have the throttle open all the way when cranking for the test, with lanyard disconnected. I do not run them on choke except when starting cold. Usually takes about 15 seconds of running on choke in between all the attempts each time I take it out after sitting for a while. So the newer looking ones from Port engine have about 45 seconds to 1 minute of running OK choke in their lifetime.
Starboard ones are closer to 3 to 5 minutes throughout their lifetime, but all in 5 to 10 second intervals when I am trying to start the engines cold.What does it mean to be gas fouled?
Bent top at the cap is from closing my box on it after I pulled it out. Was OK in the engine.
Expert:  Kenny O. replied 5 months ago.

Gas fouled usually occurs from over choking, I will post up this PDF file go ahead and down load it and check the wires.

I think with new plugs and checking the wires as long as the compression is up there, I thinks you'll be OK

Thanks

http://spaces.hightail.com/receive/n1vBA

Customer: replied 5 months ago.
Hi Kenny, I tried to follow this last night, but I could not open the link. A few hours before that, I did get it open at the office, but it looks like I've closed it since. Could you please repost.
Expert:  Kenny O. replied 5 months ago.

OK, just make sure that when you view it that you download and save a copy, the files will go away right after.

Thanks

http://spaces.hightail.com/receive/UuLLt

Customer: replied 5 months ago.
Hi Kenny. I got my replacement starter for the port engine today. I will put in in, and perform a compression test. Will follow up with findings. I cleaned out the spark plug cables (they had lots of black "dust"), and put new plugs into the starboard motor. That motor still does not go over 4k RPMs.
Expert:  Kenny O. replied 5 months ago.

Get back to me when you get them both running, and let me know the RPM's you get out of the port engine.

Customer: replied 5 months ago.
Port engine at 82, 85 and 80 psi running cold with full throttle. Can I throttle it out of the water with a hose to check rpms, or do I need to drop it in?
Expert:  Kenny O. replied 5 months ago.

No you can rev it up out of the water, if there is a runnibility issue with that engine and its sensitive to being under a load then it might not show up running unloaded, but you can rev it up all the way, if you are not going to run water in the engine then I wouldn't go much past 30 seconds.

Customer: replied 5 months ago.
Most I am getting is 3600rpm
Expert:  Kenny O. replied 5 months ago.

OK here is what you need to do, obviously when the engines are under a load they will react totally different then unloaded, I would pt a fresh set of plugs in both engines and then go to the lake, that way you'll be able to get some color in the spark plugs and get a true reading on the plugs and will show you more what's going on in the engines, not only will this test the engines but also the driveline, the pumps and the impellors in both pumps.

I think you are at the point that this is going to be the best.

Customer: replied 5 months ago.
Hi Kenny,
I took it out on the lake yesterday. Both engines performed just as before, topping out around 3600rpm.To summarize:
both engines starting and idling fine, rev to 3600-3800 rpm on both engines at throttle being half way up, same as before.
What has been done:
Compression test at 82,85,80, 82,82,85 on port and starboard running cold.
Switched out spark plugs, cleaned out and inspected spark plug cables.
What indicators of source of problem:
Spark plugs are black, show signs of either being chocked or gas fouled.
Expert:  Kenny O. replied 5 months ago.

Yeah you got a major issues here, you should be seeing at least 6500 + rpm. by chance have you had the covers over the carburetors off ? if not o would like you to pull the covers off both engines (8 bolts) and then pull the air cleaners, look down the velocity stacks and then you'll see the choke plates, with the chokes off the plates should be open (straight up and down) then apply the choke and make sure they close, and then release the choke an make sure that (ALL) the plates are going to fully open, might be best to get another person so you can watch the actions of the plates moving. I have a feeling if its not the plates, then maybe something with the air filters, its almost like maybe mice got into the air cleaner covers and built a nest ?

Let me know what you find, I might have you go back to the lake and maybe try with out the filters ?

Customer: replied 5 months ago.
Will do tonight and report.
Expert:  Kenny O. replied 5 months ago.

its got to be something there, had you had them off lately ?

Customer: replied 5 months ago.
No.
Expert:  Kenny O. replied 5 months ago.

OK good, I'm interested what you are going to find

Thanks

Customer: replied 5 months ago.
Kenny, when choke is pulled, fully closed. When pushed in, fully open.
Expert:  Kenny O. replied 5 months ago.

So this is a 2002 year model, have you owned since new ? have you changed the air cleaners ? Since you are good with the pictures,can you picture the air cleaners ?

I thinking of these are the original filters, we know in these boats that they don't usually get dirty, but they are subjected to water and over a period of time the paper condenses and then restricts air flow.

Take the boat out with out the filters in it ? that will tell us a whole a lot.

Also now that we are at this point, I need you to check ALL the rubber hoses on the exhaust, make sure they have not collapsed, feel for soft spots

Customer: replied 5 months ago.
Kenny,
Thank you, ***** ***** :)
I will take some pictures tomorrow morning of the filter. They do not seem dirty/restrictive, but I am not sure what to look for.
I can take it out without the filters; Is that safe? The river I usually drive through has some stuff floating in the water.I'd be happy to check the rubber hoses. When you say all the ones on the exhaust, would that be the ones going to the exhaust manifold and muffler? I can do this tomorrow as well.
One thing I thought of that might mean something to you.. at one point I adjusted my idle speed using the idle speed screw. That had some small impact on the rpms i was able to attain when throttling the boat. It was not major, like 200 rpms, but thought it might be worthwhile to share.
Expert:  Kenny O. replied 5 months ago.

Running this without air filters is not a problem, never understood why Yamaha have them, none of the other manufactures use air filter, you don't see much dirt floating in the air when on a like or a river ?

The rubber hoses are a series of layers when manufactured, I always suggest to people is pull the hoses and inspect internally, there is a way and that's with a visual and then by feel, so of one of the hose is collapsed you can visibly see it from the out side, and should be replaced, then removing the hose and you can see it from looking into the hose, what happens is when the pressure builds up in the exhaust then the part that is delaminating will actually turn into a bubble and block the exhaust, its like putting a potato in the exhaust of a car. Last if you have the experience you can do it by feel, but you need to know what you are feeling for, squeezing the hose when you feel a soft spot then usually means that the hose is coming apart internally and needs further inspection.

Customer: replied 5 months ago.
Kenny,
I've tried to run with air filter off on port engine (kept starboard in). There was no notice change. I checked all of the hoses I could reach, very carefully. I did not feel any breaks or soft spots.all cable ties are tight and connectors fitted well everywhere I could see.
I've also added pictures of the spark plugs from my port engine. I have about 3 hours of running the engines on here. I tried to only give enough throttle to where it no longer gives rpms, which seems to have created less fouling.
Expert:  Kenny O. replied 5 months ago.

Are both engines running at low RPM ?

Customer: replied 5 months ago.
Expert:  Kenny O. replied 5 months ago.

Why did you leave the air cleaner in then ?

if these engine wont pull the spec RPM then you have 4 possibilities,

  1. Exhaust obstruction
  2. Intake obstruction
  3. Bent props
  4. Engine down on power

So you have both engines acting the same, so what is likely common to be going on that would effect both engines ?

Does this boat have fresh fuel in it ?

Customer: replied 5 months ago.
I have emptied and refueled a dozen times since the problem began. I left one off to not have to take off extra screws, I figure if problem is in both and I only do it on one, it should be easier to tell if it performs better.A friend suggested checking high and low adjustment screws, although he doesn't work with jet boats much, just outboards.
If it is impacting both engines about the same, I'd figure it is a system they share. I think exhausts are seperate, so maybe part of the intake (fuel, not really sure due to my limited knowledge ).
I can't get high rpm on ground so probably not the water intake.
Any ideas how I can isolate which one it is of these four?
Expert:  Kenny O. replied 5 months ago.

I just called a buddy that use to work for me, he works on these basically every day, I pretty much told him where I was at and he agreed with everything we have checked,

He says that the fuel valves (petcock) the on reserve/on switches, he's seen problems there with getting clogged ?So maybe something with fuel in the pick-up or the valve (pet-cock) ?

The air cleaner as they call it, its not a paper element is it ?

I would not touch the carbs at this point, I definitely don't think its something there, at least not on all 6 !

Hes going to look into a few things and get back to me, this has an oil sensor, you have plenty of oil in it I'm sure ?

Customer: replied 5 months ago.
Thanks Kenny. The air filters are metallic, looks like. I have good oil filled to 95% of the tank capacity. I use fuel stabilizer in the winter before storing the boat, and have emptied and refilled the tank a few times this year.
Look forward to hearing from you,
Thanks.
Expert:  Kenny O. replied 5 months ago.

OK lets see what my buddy comes up with, but might pursue the fuel delivery ?

Good night

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