Shaking during acceleration. Yamaha 130 hp 2-stroke

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SeaSideLife

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Hi, all. (Here is a video of the issue, which has footage of two incidents in it.) Dealing with a doozy here. My Yamaha 130 hp Saltwater Edition 2-stroke is shaking and losing power when I try to accelerate. Sometimes it shakes immediately as I go above about +/- 3,500 rpms. Other times, it shakes after fully accelerating and getting on plane. When it does this, it stays on plane for around 5 or 6 seconds (at the most) and then starts quivering. The shaking is fast and rhythmic. It's faster when it begins after getting on plane, as seen in the first part of the video.

Compression readings (all within spec):
Cylinder 1: 125
2: 130
3: 121
4: 120 (This one seemed to fail the "cylinder drop" test, but I don't know if that's reliable.)

Here's what I've tried so far:
- Put in brand new plugs
- Changed the primer bulb
- Tried a different prop
- Raised the motor one notch (A mechanic recommended doing that as a general improvement, not necessarily to address this.)
- Running it using only a portable tank. (Still doing that)
- Changed the fuel line going from the portable tank to the primer bulb
- Accelerating from various trim positions
- Removed the oil level sensor to rule out it going into limp mode (That was a mechanic's idea.)

Any help would be deeply appreciated.
 
Last edited:
If it's fuel starvation. Couple things;
- Did you change fuel line between primer bulb and motor?
- Have you checked the fuel filter on the motor?
- Do you have an inline water separator filter? (between primer bulb and motor)
I'm not familiar with Yamaha electrical components so no help there.
 
Thanks for the quick reply, Bob. Here are the answers:
- Did you change fuel line between primer bulb and motor? - No, will check that
- Have you checked the fuel filter on the motor? - No, will check that, too
- Do you have an inline water separator filter? (between primer bulb and motor) - No, but I figured since I'm using fresh, 50:1 gas in a portable, closed tank, I didn't need one. 🤔
 
So, for what it's worth, I had a very similar problem with mine.

Brian N

Thread 'Yamaha 130 hp 2 stroke bogging and stuttering'

A little help would be appreciated here folks...

1997 Yamaha 130hp Saltwater Series 2 stroke

Took it out today for the first time for the season, between work and rain it's been a rough summer.

Fired right up, let it warm up for a while idling away from the ramp, then throttled up. It revved up to about 2400 RPM then bogged down... Two more times I throttled down and back up until finally is pushed through and got up to speed. We ran around the lake for a while with no trouble, idling down for slow zones and then revving back up with no trouble.

Later, heading back to the ramp, it did...

Turned out to be an anti-siphon valve from the fuel tank was failed and blocking fuel flow intermittently.
 
Brian N said:
So, for what it's worth, I had a very similar problem with mine.

Brian N

Thread 'Yamaha 130 hp 2 stroke bogging and stuttering'

A little help would be appreciated here folks...

1997 Yamaha 130hp Saltwater Series 2 stroke

Took it out today for the first time for the season, between work and rain it's been a rough summer.

Fired right up, let it warm up for a while idling away from the ramp, then throttled up. It revved up to about 2400 RPM then bogged down... Two more times I throttled down and back up until finally is pushed through and got up to speed. We ran around the lake for a while with no trouble, idling down for slow zones and then revving back up with no trouble.

Later, heading back to the ramp, it did...

Turned out to be an anti-siphon valve from the fuel tank was failed and blocking fuel flow intermittently.
Click to expand...
Thanks for that. I actually read your thread earlier today. I haven't seen any kind of anti-siphoning valve on the tank, though. It's just a regular portable tank. I'm going to take another look at it though. I did try loosening the little screw that helps it "breathe." No dice.

Or I might try running it on a different tank altogether--just to rule out those kinds of issues.
 
SeaSideLife said:
Thanks for that. I actually read your thread earlier today. I haven't seen any kind of anti-siphoning valve on the tank, though. It's just a regular portable tank. I'm going to take another look at it though. I did try loosening the little screw that helps it "breathe." No dice.

Or I might try running it on a different tank altogether--just to rule out those kinds of issues.
Click to expand...
That little screw allows the gas to flow. When it's closed, the tank creates a "vacuum" as the fuel flows out. That will choke out your engine. (First boat had two portable tanks. Ask me how I know this.) :cool:
 
Bob Ware said:
If it's fuel starvation. Couple things;
- Did you change fuel line between primer bulb and motor?
- Have you checked the fuel filter on the motor?
- Do you have an inline water separator filter? (between primer bulb and motor)
I'm not familiar with Yamaha electrical components so no help there.
Click to expand...
Hey, just a quick update: I changed the fuel filter, and there was no improvement.
Also, here are the compression readings and the result of the "cylinder drop" test, FWIW:
Compression readings (all within spec):
Cylinder 1: 125
2: 130
3: 121
4: 120 (This one seemed to fail the "cylinder drop" test, but I don't know if that's reliable.)

Attaching a video so you can see the difference between when I removed the wire from cylinder 2 and cylinder 4.
 
SeaSideLife said:
Thanks for that. I actually read your thread earlier today. I haven't seen any kind of anti-siphoning valve on the tank, though. It's just a regular portable tank. I'm going to take another look at it though. I did try loosening the little screw that helps it "breathe." No dice.

Or I might try running it on a different tank altogether--just to rule out those kinds of issues.
Click to expand...

Gotcha, mine was on the boat's own tank.
 
It almost sounds like it is "4 cycling". Does it do this out of the water on muffs or in neutral? I used to mess around with 2 strokes and when they were running too rich they would "4 cycle". Is there any additional smoke? Are the plug wires leaking arcs (check at night)? It probably would not help to pull the plugs for examination once back at the dock as they would most likely clean up. Is the intake clear?
Did this "just start happening" or is this part of recommissioning after Winter?
 
Does your motor have power packs for each spark plug? My old Johnson had them and I had to replace a few of those over the years.
From what I found on quick search is cylinders 3 & 4 have a lower compression ratio so your numbers look okay.
You might consider running some Seafoam (or similar) in the gas as one of the carbs could possibly have a sticking float valve.

Just saw Dan's post. Didn't think of the plug wire leaking, BTDT.
 
boatbum said:
It almost sounds like it is "4 cycling". Does it do this out of the water on muffs or in neutral? I used to mess around with 2 strokes and when they were running too rich they would "4 cycle". Is there any additional smoke? Are the plug wires leaking arcs (check at night)? It probably would not help to pull the plugs for examination once back at the dock as they would most likely clean up. Is the intake clear?
Did this "just start happening" or is this part of recommissioning after Winter?
Click to expand...
No, it doesn't do it when on muffs or in neutral. There's also no additional smoke. The intake looks clear, too. And, yeah, it just started happening. One potential clue could be one of the coils was replaced about two rides before it started happening (2 days before). Yesterday, I tried the cylinder drop test and when I pulled the coil that had been changed, there was no effect on how the engine ran (there was a significant change when I pulled the others). I also got a shock as I pulled it.

But I don't know if the drop test is even reliable or if that shock definitely indicates a ground fault or not. Any thoughts?
 
Bob Ware said:
Does your motor have power packs for each spark plug? My old Johnson had them and I had to replace a few of those over the years.
From what I found on quick search is cylinders 3 & 4 have a lower compression ratio so your numbers look okay.
You might consider running some Seafoam (or similar) in the gas as one of the carbs could possibly have a sticking float valve.

Just saw Dan's post. Didn't think of the plug wire leaking, BTDT.
Click to expand...
Hey, thanks. No, it only has one power pack for all four spark plugs. That's good news about the compression. Thanks for that. I'm going to try the Seafoam and check out the carbs, too. From the video on my first post, do you think blocked or jammed carbs could cause that kind of effect?
 
I gave the wrong name earlier........it should have been coil rather than power pack.
Based on the failure timeframe I would swap the new coil with a different one to determine if the 'drop test' follows that coil. You should have a noticeable different on every one. Wouldn't be the first time a new part was bad/failed immediately.
 
Bob Ware said:
I gave the wrong name earlier........it should have been coil rather than power pack.
Based on the failure timeframe I would swap the new coil with a different one to determine if the 'drop test' follows that coil. You should have a noticeable different on every one. Wouldn't be the first time a new part was bad/failed immediately.
Click to expand...
Right, why didn't I think of that? lol OK, gonna try that
 
Bob Ware said:
I gave the wrong name earlier........it should have been coil rather than power pack.
Based on the failure timeframe I would swap the new coil with a different one to determine if the 'drop test' follows that coil. You should have a noticeable different on every one. Wouldn't be the first time a new part was bad/failed immediately.
Click to expand...
So I tried this yesterday evening. After swapping the coil, the problem did not travel. It stayed on the same cylinder. I'm thinking there may be an issue with the carb that feeds that cylinder. Going to try cleaning all of them today after work. But is there something else I should be considering?
 
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