Engines almost stalling??

[VCinRI]

I have twin Yamaha 225 2 strokes on my 27' Sailfish.
On several occasions, while cruising in fairly good sea, I will come down a wave and bury the bow in the next. The sudden stop,so to speak, will result in an almost stall of the engines. One did stall at one time.
My original thought was that the sudden stop may have created a fuel surge in the tank and caused a air pocket in the fuel pick up. ( My tank is usually full)
Could it be the engines got overloaded by the sudden increased strain?

I did have someone say my fuel pumps were going.

Any advice would be appreciated.

Thanks,
VC

 

[seasick]

A fuel pickup problem is a good possibility. So is something electrical that is loose and the shock of the boat nosediving causes a loss of power to the ignition. I guess one way to try to tell would be to judge how much time it takes after the shock for the motor to stall. If it is instantaneous, I would lean towards an electrical issue. If there is a small delay, a few seconds or so, fuel is more likely.

 

[BobP]

Both engines want to stall or just one?

 

[teaklejr]

I have 200 hpdi's on my Tigercat and when the VST filter on the starboard motor got clogged it would kind of do the same thing. Loose power then pick back up. Installed new VST filter and o-ring she was good to go. Did both sides at the same time. Not sure if this is the problem but I know it is common.

 

[VCinRI]

Both engines do it.
It very well could be an electrical issue never really of thought of it.
I had another issue but I am not sure it is related. Sometimes on the same scenario of a sudden loss of speed the starboard control lever started chattering like it wanted to jump out of gear. I made a tension adjustment at the control since then and have not really put it to the test yet.

Thanks for all the help.

VC

 

[seasick]

Both engines do it.
It very well could be an electrical issue never really of thought of it.
I had another issue but I am not sure it is related. Sometimes on the same scenario of a sudden loss of speed the starboard control lever started chattering like it wanted to jump out of gear. I made a tension adjustment at the control since then and have not really put it to the test yet.

Thanks for all the help.

VC

I don't think the chattering is related to the problem. The fact that both motors stall pretty much eliminates a motor issue. It is something common to both motors, electrical or fuel. As mentioned, if it happens very quickly when the boat slams the water, I would suspect electrical first. Since there are common electrical points at the helm (ignition feed) and the fact that the forward part of the boat will receive a lot more stress when slapping than the stern, I would start looking at the helm electrical wiring. Remember, if you have 2 kill switches and 2 ignition switches, it would be something common to both like a loose fuse or fuse holder, fuse panel 12v connector, fuse block ground etc.

 

[grady33]

I would replace the VST filter and also look at the 3 low pressure fuel pumps. I have at least 2 go out and it would cause the same problem. They are so cheap and we go so far offshore that I just go ahead and replace the pumps every 3 years or so depending on how much we use the boat. I know it could be a waste of money but it would be a long ride home from 60 miles offshore. VST filter could also be the issue.

 

[bayrat]

Grady 28 and teaklejer have it right. I have heard a ton of stories of yamahas with these exact symptoms and all of them were the vst tank. Thats where I would start. Good luck

 

[seasick]

Grady 28 and teaklejer have it right. I have heard a ton of stories of yamahas with these exact symptoms and all of them were the vst tank. Thats where I would start. Good luck

I find it hard to believe that a VST issue would affect both motors in exactly the same way and at the same time.

 

[bayrat]

I find it hard to believe that a VST issue would affect both motors in exactly the same way and at the same time.[/quote]

I agree that it seems like a bit of a long shot but isnt it possible that there could be so much crap in both that when disturbed (as in crossing a wake) that it causes a momentary lean condition in both engines? I'm only putting that out there because I have read so many stories of "bogging problems after crossing a wake" that turned out to be the VST tank. I would think that an electrical problem would usually shut it down totally rather than just cause a rpm drop but I realize that that anything is possible. The checks you mentioned are a great place to start (easy and free). Mine, not so much. Hopefully he'll solve the problem and let us know the results.

 

[seasick]

I find it hard to believe that a VST issue would affect both motors in exactly the same way and at the same time.

I agree that it seems like a bit of a long shot but isnt it possible that there could be so much crap in both that when disturbed (as in crossing a wake) that it causes a momentary lean condition in both engines? I'm only putting that out there because I have read so many stories of "bogging problems after crossing a wake" that turned out to be the VST tank. I would think that an electrical problem would usually shut it down totally rather than just cause a rpm drop but I realize that that anything is possible. The checks you mentioned are a great place to start (easy and free). Mine, not so much. Hopefully he'll solve the problem and let us know the results.[/quote]

I hope so.
It could be fuel starvation also but there has to be a common point there too. I don't know how fuel is plumbed in that boat. If there is a single pickup, that could be a clue. When the boat slams a wave, there isn't really that much more shock at the motor. There is a lot more towards the bow. However, if the problem occurs when plowing through a wave, there is forward momentum that gets dampened. That force is pretty much uniform throughout the boat. Fuel in the tank will slosh forward and there could be a pickup issue.
I suppose there could be a VST float issue too but I can't remember which way the VST float faces. If the float is forced UP ( not down) it will shut off the fuel flow.