Yanmar engine problem(?)

[KeithK]

Hello all,

Please help, I am asking for any advice, in case anyone has experienced the engine problem I did this past weekend aboard my Ranger 21EC. After running at just under full throttle for about 3 minutes, the engine began to 'shake/vibrating the hull', I immediately throttled down, and found I could run at about 2200rpms, yet, if I began to throttle up, the shaking started. At first I thought I had possibly run over a crab pot line... I was in the channel and didn't see anything before or after. The engine did shut off on its own one time, was able to restart, and I subsequently limped back to the launch ramp. At the dock, I put her in neutral and revived up the engine, it went easily up to full throttle (about 4000rpm), smooth, no problem, seemed to run like a top. It seemed now that when there was a load on the engine, it just wanted to sputter/vibrate... and possibly shut down. (Before all of this occurred, I had been running the boat for about 1/2 hour, kinda cruising at 2000rpm).

When I pulled her out of the water, there wasn't any kelp, line, anything on the prop, everything looked good, the cutlass bearing is excellent. So, that is my dilemma. Any ideas of what is possibly wrong? Could the fuel filters need changing, even if I could throttle up in neutral?

Here are some 'facts': Engine hours @ 117, fuel tank was about 1/3 full, Yanmar engine model 3YM30, total of 4 adults on board, and lastly, my boat was in covered storage for about 8 months prior to this weekend; everything was running smooth until I full throttled up for that short period of time.

Any thoughts? Advice? Thank you very much,
Keith
P.S. This is the 3rd Yanmar that I have had over the years in various boats, never experienced this situation.

 

[baz]

1/3 tank full and 8 months in covered storage may mean water in fuel tank from condensation. Check fuel filter drain plug for water. Just a suggestion.... Good luck.

 

[Favunclerich]

Check the engine mounts.

 

[SGIDAVE]

Hello Keith,

While your description could be explained by a number of issues, I would plan on replacing both fuel filters. Given your history of 1/3 tank fuel and a LONG period of no use the fuel system is where I'd start. Algae will grow in the fuel/water interface which may ultimately partially plug the filters. If the filters you remove are really heavily soiled with black slimy stuff (which is algae) you may have to pump out and discard the remaining bad fuel.

While you are checking that, I'd also snug up the hose clamps and generally make sure there is no place for air to be entrained into the fuel system (another cause of rough running engine). At WOT there is enough suction to draw air through a loose hose fitting or fuel filter assembly.

Let us know what solves your issues.

David

 

[ireilly]

I had a similar problem at about the same engine hours. Mine was the mixing tube being clogged. If all the other solutions are eliminated, you might want to check it out.

 

[rt11002003]

It's more likely to be a fuel issue. But, I'd also the prop shaft for alignment.

 

[doke01]

What model Yanmar? Sounds like a loose injector.

 

[daviduphoff]

Check your fuel filters!!!
If there is any water in them change them and then pump your fuel tank dry. As far as that goes, change them either way. I am over $2500 into injector repair and injection pump repair. Dumping six gallons of fuel is cheap insurance.

Questions, PM me.

David