Cutting out and stalling

[BOWTECH.JUSTICE]

What led you to replace the low pressure pump? When it stalled, were the plugs wet or dry? Any issues since?

So, this boat is a rental boat and I havent had time to be with the boat to test everything. ( Last child graduation, spring track meets, etc.) A friend of mine was using the boat, he is also very good with motors, said it stalled on him and he thought maybe the diapragm might be weak in that pump. Kinda made sense so with limited time and wanting to keep renters happy, I ordered one and changed it.
I have not checked the plugs after it stalls but will keep that in mind.
After I changed that pump, I took it for a drive, mostly in low idle and after some time it still stalled on me but after a couple tries it starts back up.

 

[BOWTECH.JUSTICE]

So, this boat is a rental boat and I havent had time to be with the boat to test everything. ( Last child graduation, spring track meets, etc.) A friend of mine was using the boat, he is also very good with motors, said it stalled on him and he thought maybe the diapragm might be weak in that pump. Kinda made sense so with limited time and wanting to keep renters happy, I ordered one and changed it.
I have not checked the plugs after it stalls but will keep that in mind.
After I changed that pump, I took it for a drive, mostly in low idle and after some time it still stalled on me but after a couple tries it starts back up.

Just last night, renters came in and said motor was running at extremely high idle. I found the fuel line going in to the vapor separator had a cut in it. Changed that and fixed the idle issue. Could that little hole be tied to the stalling and when it got bigger caused the idle issue? Hopefully.

 

[pvanv]

Possible, as once the high pressure side runs out of gas, it won't run.

 

[BOWTECH.JUSTICE]

Possible, as once the high pressure side runs out of gas, it won't run.

Shouldnt it sputter at least a little bit when it stalls because of fuel. When it stalled for me last night it just shut off. Thanks so much for your advice.

 

[BOWTECH.JUSTICE]

Possible, as once the high pressure side runs out of gas, it won't run.

Update. It stalled again a couple times. Now im convinced its something electrical.

 

[pvanv]

Intermittent electrical will drive you nuts. If it only happens warm, you must test exactly when it fails.

 

[Sea Rider]

Intermittent electrical will drive you nuts. If it only happens warm, you must test exactly when it fails.

Should drive you what comes inmmediately after nuts, those electrical components cools so fast that proably won't have time to test them while warm to find a quick culprit.

Happy Boating​

 

[BOWTECH.JUSTICE]

Intermittent electrical will drive you nuts. If it only happens warm, you must test exactly when it fails.

Intermittent electrical will drive you nuts. If it only happens warm, you must test exactly when it fails.

So I finally got it to act up for me. Took it out and ran it, this time it didnt takes so long for it to stall. I was actually running almost wide open throttle and it just shut off. Cranked it a couple times and started up. Drove maybe 2 minutes stalled again. This time I cranked and cranked and cranked and would not start. Once it started, did not want to stay running. Then it got to a point it would not start at all, almost like it wasn't getting a spark. It felt dead like it was not going to start. Then I got it running again, and I could tell it was about to stall and I started working the throttle and it seemed to help keep it running. But eventually it shut off. It has me baffled one second it seems like a fuel issue, next second it seems electrical. I do believe it's electrical because it does not sputter before it is stalling. I'm currently hauling the boat home to my shop so I can do more testing on components.

 

[MattFL]

If you think it's a heat related problem, which is not unheard of with electronics, what you can do is start it on the muffs or in a bucket and get under the hood with a hair dryer and carefully heat suspect components to see if you can induce a failure, then check if cooling the part resolves the problem. Don't use a heat gun, it's too hot.

Also with it running on the muffs you can get under the dash and/or under the hood and start jiggling and pushing on wires to see if you can induce a failure. Also jiggle and tap on the lanyard kill switch and the key switch.

 

[BOWTECH.JUSTICE]

Did compression check today. Readings were 75, 75, 71. Specs are 108-132 but it also says lowest reading should be within 15 psi of the highest reading. Could low compression be what's causing these issues?

 

[MattFL]

Your original post says it runs great then it starts missing and stalls. If it's initially running great, then you don't have a compression issue, it's something else making it stall.

That said; when you ran a compression test, did you do it with the throttle wide open? If not then that might account for the low numbers.

 

[BOWTECH.JUSTICE]

Your original post says it runs great then it starts missing and stalls. If it's initially running great, then you don't have a compression issue, it's something else making it stall.

That said; when you ran a compression test, did you do it with the throttle wide open? If not then that might account for the low numbers.

I had throttle in neutral. According to the manual, it says that the throttle doesnt make much difference in the readings. I will try it again though.
I also read that low compression can come from excess carbon so I am going to try and do some decarbonizing. Although, it might be baked on there pretty hard by now.

What about the rectifier?
Im going to do a test on it next because a wire coming from it today was very hot.

I now have this motor on a stand so Im no longer under pressure.

 

[pvanv]

What manual are you using? Trash the aftermarket manuals, and get a Factory service manual. Also read out any error codes stored in the ECU, then reset TPS initial setting and see if you get any more malfunctions or any codes. Carbon in the combustion chambers will raise the compression, not lower it. Yes, you could have some sticky rings, but doubtful to have that on all 3 cylinders. More than likely the gauge just reads a little low. The rectifier/regulator should not cause a stall, especially not one that restarts right away.

 

[BOWTECH.JUSTICE]

What manual are you using? Trash the aftermarket manuals, and get a Factory service manual. Also read out any error codes stored in the ECU, then reset TPS initial setting and see if you get any more malfunctions or any codes. Carbon in the combustion chambers will raise the compression, not lower it. Yes, you could have some sticky rings, but doubtful to have that on all 3 cylinders. More than likely the gauge just reads a little low. The rectifier/regulator should not cause a stall, especially not one that restarts right away.

You guessed it. I have a manual from marine engines.com.
I read elsewhere that carbon in the piston grooves contributes to low compression. Regardless, it probably wont hurt to try to decarbon.
As far as everything else, Im just drawing straws to find the issue and Im very grateful for the advice you all give because I definitely am no expert.
Before I decided to take this motor off, it really acted up for me. Put new battery on it and drove it for 5 minutes and it just shut off. Started right back up. Drove for 2 minutes and shut off agsin. This time would not start. Seemed like no spark. Then acted like it was going to start but wouldn't stay running. 10 minutes later, started. Ran for 5 minutes, I could tell it was going to stall and I quickly worked the throttle back and forth and it prolonged the stall for a few seconds but did shut off. At that point I had to switch motors because I had a spare.
I did check the kill switch as its running, did nothing to affect it.

 

[pvanv]

Decarboning always helps. Sounds like an ECU or exciter issue for the stalling.