05 AR230 H.O port engine start issue / power

[euro_e30]

Port engine starts and runs great on land , when we dropped it in the water today it would start idle for 2-3 sec with rpm jumping and then die, if I gave it throttle and held it about 1,500 it ran just fine. On top of this it seems like there is not much thrust power , both motors ran great 2-3 weeks ago with lots of power after new ecu install , slowly it seemed like I would losing speed / power , not when I have it at 7-8k at start up it seems like in cavitating a lot, could a pump issue be causing the bad idle when in the water or is this totally separate ?

Few possible things I would thinking something stuck inside the jet pump ? I did remove the jet pumps from the boat and found a fishing line wrapped around the shaft I was able to spin it freely but did not dissemble it to see if anything was going on inside, we have also only been seeing 35-40mph at best maybe so I think pumps need to be rebuilt on top of all of this

Any help would be appreciate

 

[itsdgm]

A piece of fishing line could definitely cause cavitation. Hopefully that was it. Also, changing the spark plugs usually cures most engine issues on our vintage of Yamaha boats. Best of luck with the repair, it’s probably something really simple.

 

[euro_e30]

A piece of fishing line could definitely cause cavitation. Hopefully that was it. Also, changing the spark plugs usually cures most engine issues on our vintage of Yamaha boats. Best of luck with the repair, it’s probably something really simple.

Thanks I’ll check it out , I did plugs after the new ecu and have about 4 hrs on them now I’d be surprised if those went bad already but it’s a cheap check I can always replace them again

 

[David Martin]

I'm with itsdgm its probably something simple ..................yes pull pumps and clean any lines ect........WHILE you are their caulk all gaps in the tunnel area and smooth it best as you can.

Now the engine stumbling is not caused by the impeller...........stumbling motor at start that's get better as RPMs go up is a Fuel air ratio mix problem. Their are a few things that can change this ratio mix to cause to cause a poor running engine loose power and start poorly. First is corrode/dirty fuel injectors( fresh plugs will compensate) for this for a while. Dirty air cleaner.......Third are sensers like MAP (Mass air flow) senser and the throttle position senser TPS.

These sensers gives the EMC computer info to adjust the Air/Fuel Raito to somewhere in the target range of 14:1......................good performance......... the best performance a four cycle engine is around a 12:1 ratio for maximum power. USUALLY if one plays down around 12:1 it will have an oxygen senser in the mix because if you screw up a 12:1 lean ratio will damage and burn the engine up fairly quickly. Maybe Yamaha can play this mix close to 12:1 with out an O2 senser but I'm saying probably not.....

Sorry back to your problem your Air/fuel ratio mix is off because your idle stumble and the loss of top end power. The MAP and TPS are an easy voltage/ohm check and injector cleaning is simple also.

Good luck

 

[euro_e30]

I'm with itsdgm its probably something simple ..................yes pull pumps and clean any lines ect........WHILE you are their caulk all gaps in the tunnel area and smooth it best as you can.

Now the engine stumbling is not caused by the impeller...........stumbling motor at start that's get better as RPMs go up is a Fuel air ratio mix problem. Their are a few things that can change this ratio mix to cause to cause a poor running engine loose power and start poorly. First is corrode/dirty fuel injectors( fresh plugs will compensate) for this for a while. Dirty air cleaner.......Third are sensers like MAP (Mass air flow) senser and the throttle position senser TPS.

These sensers gives the EMC computer info to adjust the Air/Fuel Raito to somewhere in the target range of 14:1......................good performance......... the best performance a four cycle engine is around a 12:1 ratio for maximum power. USUALLY if one plays down around 12:1 it will have an oxygen senser in the mix because if you screw up a 12:1 lean ratio will damage and burn the engine up fairly quickly. Maybe Yamaha can play this mix close to 12:1 with out an O2 senser but I'm saying probably not.....

Sorry back to your problem your Air/fuel ratio mix is off because your idle stumble and the loss of top end power. The MAP and TPS are an easy voltage/ohm check and injector cleaning is simple also.

Good luck

Thanks for the input I’m going to replace the impeller housing while I’m in there bearing feel tight, just an update on the erratic idle / shut off I went to pull the plugs and as I pulled one of the coils out the whole plug came out , some how it snapped inside of the engine , was able to get it will vaccum that cylinder and install a new plug and give it a shot

 

[Julian]

Thanks for the input I’m going to replace the impeller housing while I’m in there bearing feel tight, just an update on the erratic idle / shut off I went to pull the plugs and as I pulled one of the coils out the whole plug came out , some how it snapped inside of the engine , was able to get it will vaccum that cylinder and install a new plug and give it a shot

Well that'll cause stumbling! Glad you found that quickly!

 

[David Martin]

WOW!!!!! nice use of the easy out. That plug failed/snap off after being heated up.......... and ran good for a few hours.....shaking head now

 

[itsdgm]

Thanks for the input I’m going to replace the impeller housing while I’m in there bearing feel tight, just an update on the erratic idle / shut off I went to pull the plugs and as I pulled one of the coils out the whole plug came out , some how it snapped inside of the engine , was able to get it will vaccum that cylinder and install a new plug and give it a shot

Dang, I haven’t seen one snap off like that in years. It was an issue about ten years ago. So much so that I bought an easy out and keep it in the boat just in case. Part of the problem is that we’re only supposed to torque them down to 13NM (9.4’ lbs). I usually thread a new plug in by hand until in reaches the bottom and then wrench it down only 1/4-1/3 turn. The plugs are so small and there was a bad run of them years ago so guys were snapping them off more regularly.

Hopefully that solves your issue.

 

[euro_e30]

Dang, I haven’t seen one snap off like that in years. It was an issue about ten years ago. So much so that I bought an easy out and keep it in the boat just in case. Part of the problem is that we’re only supposed to torque them down to 13NM (9.4’ lbs). I usually thread a new plug in by hand until in reaches the bottom and then wrench it down only 1/4-1/3 turn. The plugs are so small and there was a bad run of them years ago so guys were snapping them off more regularly.

Hopefully that solves your issue.

That’s for the input I was planning on using a torque wrench this time around just to ensure I didn’t over tighten them will keep you posted this weekend if this is the issue

 

[itsdgm]

That’s for the input I was planning on using a torque wrench this time around just to ensure I didn’t over tighten them will keep you posted this weekend if this is the issue

I stopped using the torque wrench and just thread them in by hand and then wrench another 1/4-1/3 turn to crush the washer.

Looking forward to hearing your results. Hopefully it’s all fixed up now.

 

[euro_e30]

I stopped using the torque wrench and just thread them in by hand and then wrench another 1/4-1/3 turn to crush the washer.

Looking forward to hearing your results. Hopefully it’s all fixed up now.

Makes sense that’s how I’ve always done it maybe it was just a bad plug I’ll keep yall updated