Starboard Engine Cutting Out

[Fishwater2002]

So I recently bought a boat with some known issues, originally I was under the impression that there was an impeller problem & cavitation. See my earlier thread for the whole story
https://jetboaters.net/threads/buying-a-used-boat-with-a-cavitation-issue.42250/

It ends up that after a ton of great suggestions here that there wasn’t an issue with the impeller & that I should reseal a few areas. After doing so & replacing the plugs we finally had time to take the boat out to test. Prior to testing I replaced all 8 spark plugs, both #3 plugs were rusty & looked terrible. I did a compression test & all the cylinders except for both #3 plugs wires exactly 151psi across the board with the exception of both #3 cylinders which were exactly at 125psi, my assumption is that there may have been some rust on the valve seats causing the valves to hang slightly open. Fuel was supposedly treated but I topped off with fresh super unleaded & added 60ozs of Sea Foam to treat the fuel. I purchased YDS & checked for codes, sure enough the starboard side had codes stored from when the original owner injected a piece of wood, approximately 3 hours prior to my ownership. Other than that everything looked good. While going over the boat I noticed that the starboard side motor was idling around 1200 RPM so I turned the throttle screw up to get the engine idling around 1900 RPM like the port side.

Finally got the boat in yesterday & at first ran great, hopped up on plane with no issues. Maxed out at 10k RPM & cruised around at varying RPM’s testing & trying to burn the fuel out. After a half hour or so I started to notice the starboard engine dropping RPM’s, just slightly & intermittently at first but then the tach started jumping from 7,000 RPM’s down to 5,000 then eventually it stalled. Trying to restart it with no luck we started to limp home on the port engine, after a few minutes the starboard restarted & worked fine but then eventually as I cruised in at 7,000 RPM’s it started cutting out again with the needle bouncing between 5-7,000 until I was in the no wake zone. So here I am now after pulling the boat for the day wondering what my next step is & asking for help. I’m thinking possibly ignition related or electronic since it got worse once it was warmed up?

 

[Fishwater2002]

The plug picture on the left is the original starboard plugs prior to installing new, pic on the right side is the original port side prior to installing new.

 

[Babin Farms]

Have you checked your oil? Does it smell like gas? I had some engine issues a while back and it was the ECM. Hers my thread about it.

https://jetboaters.net/threads/mr1-issues.38022/

 

[Fishwater2002]

Have you checked your oil? Does it smell like gas? I had some engine issues a while back and it was the ECM. Hers my thread about it.

https://jetboaters.net/threads/mr1-issues.38022/

The previous owner did the ECM’s about 3 years ago, had the same situation as dumping fuel so he sent them out to be repaired. When I last checked the oil smelled fine but I didn’t check it yesterday when we came off the water so I’ll do that later when I tow the boat home.

 

[Babin Farms]

The previous owner did the ECM’s about 3 years ago, had the same situation as dumping fuel so he sent them out to be repaired. When I last checked the oil smelled fine but I didn’t check it yesterday when we came off the water so I’ll do that later when I tow the boat home.

After I had mine repaired I had the same issue on the same ECM with a different cylinder later that summer. I ended up buying a new ECM.

 

[Fishwater2002]

Have you checked your oil? Does it smell like gas? I had some engine issues a while back and it was the ECM. Hers my thread about it.

https://jetboaters.net/threads/mr1-issues.38022/

I just checked the oil, it’s at the same level as the other engine, it may smell a little like fuel or may be slightly thinner but it’s only slightly, nothing major or obvious. I see the ECU is over $1300 per side & the coil packs are NLA so not sure where to go from here? Are coil packs common? Does anyone offer reman ECU’s?

 

[Babin Farms]

I just checked the oil, it’s at the same level as the other engine, it may smell a little like fuel or may be slightly thinner but it’s only slightly, nothing major or obvious. I see the ECU is over $1300 per side & the coil packs are NLA so not sure where to go from here? Are coil packs common? Does anyone offer reman ECU’s?

There are links in the first post of my linked post on where to get it repaired if needed. Coil packs are rare to crap out and you can check them by swapping out with a known good one or just swap all 4 from the other engine. I numbered mine to keep track of them.

Something simple to try, I would put new plugs in it and see what happens. I went through a few sets of spark plugs diagnosing my issues.

 

[Fishwater2002]

There are links in the first post of my linked post on where to get it repaired if needed. Coil packs are rare to crap out and you can check them by swapping out with a known good one or just swap all 4 from the other engine. I numbered mine to keep track of them.

Something simple to try, I would put new plugs in it and see what happens. I went through a few sets of spark plugs diagnosing my issues.

Since both ECU’s hve been repaired I was thinking of swapping sides to see if the problem moves, I can also do the same with the coil packs. I just did new plugs but I guess it’s possible to have fouled them already? Finally I also checked the switches for my clean out plugs & found the starboard side was seized in the down or on position, maybe I should replace them regardless?

 

[Babin Farms]

I would swap ECU’s as last resort due to it being a pain to do. Just because they have been repaired means nothing. I had a second injector on the repaired ECU hang open months after repair which is why I just bought new. They only repair the problem area and don’t go through the whole ECU. The MR-1 engines are finicky with spark plugs. Some will have plugs in for years with no issues and others go through a set or two a year.
It would be a good idea to replace the hatch switch just out of safety.

 

[Fishwater2002]

I just pulled the new plugs that I installed last week before the water test. 3 of the starboard plugs were very wet when I pulled them & could see that the top of the pistons were wet. The port side only had #3 plug being wet. I tried to burn off some of the liquid with no luck, almost seemed like it could be water but the plugs do smell like gas. I’m starting to wonder if the ECU is bad again on the starboard side? Or maybe even both?