RMP questions 115 Mariner

[davidf5252]

Re: RMP questions 115 Mariner

oh and i forgot to mention when at WOT full speed and trimmed up the prop is dang near if not piercing the top of the water... the motor only has 2 more notches it could move up... so im going to leave it where it is for now...

 

[j_martin]

Re: RMP questions 115 Mariner

Oh I know and I believed you when you told me but it is always nice to call and ask other ppl for different opinions

Well I went home and put new plugs in her and some seafoam....

When at idle for a while and i hit it some times it would bog so bad it would cut off...but when running and then stopping for say 1 minute then hitting it she would jump up GREAT and plane out within seconds...she was spinning 5800 RPM on 2-3 chop consistently

So the only real problem is when at idle for a few minutes no matter what i do she wants to bog and cut off....but after that and she runs i can stop and start and she doesn't do it...

seems as if it is flooding while at idle???? it idles at 800-900 RPMS...

Im still going to check compression and go through it to make sure it is tip top as i dont want to ruin this motor...

Thanks for all your help!!!!

You know, when you get all the information together, things begin to clear up. This idle thing is significant.

Probably, you are running rich on one or more carbs at idle. It could be adjustment, or it could be a leaking needle, sunk float, loose idle jet, bad gasket, etc, all of which are addressed when putting a kit in a carb.

When it idles rich, one or more plugs will foul. Then when you can it, not all cylinders are hitting. To the untrained ear, it sounds like a bog, but it's really ignition miss, maybe combined with low output due to overfueling momentarily. If one of the plugs doesn't clear out, which is likely if this scene goes on for some time, you'll lose about 20% at WOT, which is about what you reported. Again, the untrained ear doesn't hear the miss, just notes the lag in performance.

If your prop shaft is 2 inched below the pad, the prop will be fully submersed. Your boat is at an angle, and so is the water as it is rising from under the boat. Setback has something to do with that also. Some hulls have a setback built into them. It isn't real complicated, but it isn't a one setting fits all deal either.

Your prop ain't piercing, or any where near it, or you wouldn't have a powerhead without a low water pickup. It might be throwing a hellova rooster tail, but that is due to the excess trim needed to get it anywhere near it's preferred position.

I'm done trying to help you with small pieces of information at a time, and questions unanswered. It's way too time intensive.

hope it helps, have fun.
John

 

[davidf5252]

Re: RMP questions 115 Mariner

You know, when you get all the information together, things begin to clear up. This idle thing is significant.

Probably, you are running rich on one or more carbs at idle. It could be adjustment, or it could be a leaking needle, sunk float, loose idle jet, bad gasket, etc, all of which are addressed when putting a kit in a carb.

When it idles rich, one or more plugs will foul. Then when you can it, not all cylinders are hitting. To the untrained ear, it sounds like a bog, but it's really ignition miss, maybe combined with low output due to overfueling momentarily. If one of the plugs doesn't clear out, which is likely if this scene goes on for some time, you'll lose about 20% at WOT, which is about what you reported. Again, the untrained ear doesn't hear the miss, just notes the lag in performance.

If your prop shaft is 2 inched below the pad, the prop will be fully submersed. Your boat is at an angle, and so is the water as it is rising from under the boat. Setback has something to do with that also. Some hulls have a setback built into them. It isn't real complicated, but it isn't a one setting fits all deal either.

Your prop ain't piercing, or any where near it, or you wouldn't have a powerhead without a low water pickup. It might be throwing a hellova rooster tail, but that is due to the excess trim needed to get it anywhere near it's preferred position.

I'm done trying to help you with small pieces of information at a time, and questions unanswered. It's way too time intensive.

hope it helps, have fun.
John

well i didnt mean to **** you off or not anwer questions you have asked. I appreciate the information and you have helped me tremendously.


Like i said before I will take your advise and measure the prop in relation to the pad, i will also look at the carbs and check for leaks or flooding, I will check compression and test the spark.....

I dont want you to think you're wasting your time as i intend and WILL do all of the things you have suggested...i just have not ran out and bought the tools to do it yet....

If you dont want to answer any more questions I understand you have been more than helpful thus far...

thanks.

 

[davidf5252]

Re: RMP questions 115 Mariner

"
Your prop ain't piercing, or any where near it, or you wouldn't have a powerhead without a low water pickup. It might be throwing a hellova rooster tail, but that is due to the excess trim needed to get it anywhere near it's preferred position."

this makes sense and is correct. I think to be safe though and not raise my motor up and install a low water pick up...I know i am going to lose some top end but she is fast enough as is....yes i would like to have a boat that goes 80mph but that will come in time...

again, as frustrating as all of my questions are I appreciate your patience and once i do all the things you have suggested I will give you an update and let you know how it all turned out. As of now she is getting 5800 RPM and running great...

Ill figure out the idle/bogging issue and let you know...probably inspect/rebuild carbs if needed.. thanks.