98 speedster starboard engine shut soff

[hellz_wings]

This happened again today. Starboard engije just goes “BOOM” and stops abruptly (at speed) but the port engine is still running at this point.

I recently replaced starter on starboard engine, new plugs, adjusted low speed screws for carbs, etc. Runs alright and idles decent enough not to stall on me. Port engine runs great. Both engines run great at 1/4 to full throttle, however, after driving for about 20 mins or so at around half throttle, i go to accelerate to about 3/4 throttle and then reduce throttle to about 1/4 and i hear this boom and the starboard engine is off.

Didn’t try restarting because I wasn’t sure what it was. Tomorrrow going to check if anything stuck around the driveshaft under the boat (caught dock rope in there last week and made similar sound, removed all the rope as far as I know..) This happened before I caught rope in there and today as well.

What could this problem be? I’ve read following:

1) MPEM
2) Stator (contacts)
3) battery
4) DESS connection (but only one engine goes out.)
5) Start/stop button
6) Something stuck in impeller

Can it be anything else? I have new fuel filters and oil filters that I want to install asap.

Thanks in advance!

 

[POPPS]

Usually, unfortunately, when a motor goes BOOM, the motor has a failure, hopefully your boom is from the pump/drive shaft.

 

[hellz_wings]

Hi popps,

This isn’t the first time this happened. It did a similar noise a few weeks back while trolling at about 2500 rpm for about 15-20 mins. It also happened when i caught dock rope in the propeller. Same sounding boom all times.

 

[POPPS]

Could that boom be similar to a back fire?

 

[hellz_wings]

It could be. I’m not too familiar with what backfire would sound like on this engine. I figured I would check basic things first and go from there.

Question though: When turning driveshaft by hand, it is turning smooth but at some points in the revolution there is a slight resistance , however I am still able to turn it manually with one hand.. Not sure if this means anything.?

 

[POPPS]

The crank should turn smoothly through 360 degrees. The binding could be the pump, (hopefully), if not, it is motor related, rotary valve, gear, or crank.

 

[hellz_wings]

hmm... i am hoping pump as well. That seems like a much easier job.