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1986 Yamaha prov 150 power issue

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Yamahadude

New member
Alright so I have a 1986 pro v 150 on a 90s model procraft bass boat. The trouble I'm having is the boat runs fine on the muffs sitting the yard give it gas seems to do fine with the arm I never put it in gear and revved it.. But on the water it also idles fine but once you get to moving to put it under a load it doesn't rev past around 2-3 rpms. It will not get up on plane it's not really bogging down or surging just reaches that rpm and will not go anymore.
I cleaned the carbs, changed the fuel lines, fuel filter, new primer bowl, new plugs. I checked it's getting spark. took it out. It's doing the samn thing it did before. I even tried a different prop didn't change anything. I did notice the boat got low on gas and hit a wave it would take off to wide open throttle but died right back off again.
Is there any suggestions what else could be done. possobly just rebuild the carbs instead of trying to clean them? Possibly stator? Any suggestion or even knowing what it is would be helpful.
Thanks a lot in advance!!
 
They all roar and sound just fine on the trailer.----The motor does not need to do any work !----Compression test needs to be done.----Have you maintained the water pump ?-----Does spark jump a gap of 1 cm or better on all leads, yes or no ?-----How long have you owned this unit ?---Did the problem show up suddenly ?
 
I haven't had the boat very long, I bought it from a guy claimed it needed carbs cleaned I took it out then clean the carbs and it continued to do the same thing. That's when I noticed it got low on gas and hit a wave it took off. Checked vents to tanks. I did a compression test when I first got it. But off hand I can't remember the number but it seemed to test fine. I just checked to make sure it was sparking I didn't check the gap. the water pump is pushing water out so I figured it was fine.
 
Well I pulled each carb off and took them apart, cleaned the jets, took the floats out and needle valves out. Pretty took them completely apart and cleaned everything and put it back together. It's possible I could have missed something but I think i cleaned them pretty good
 
Did you check the fuel pumps? When bogging down, try to squeeze the primer build, see if that makes a difference.
If compression is good and you have spark, then next is fuel, carbs, fuel pumps, primer bulb, fuel filter. Once that done then report back.
Good luck.1
 
The problem seems to be it isn't really bogging just reaches a rpm but will not go anymore, just plows along. Choking seems to bring the motor down like any choke should when the motor is warm. I check fuel pumps just didn't rebuild them, and I clean the carbs but didn't see to make a difference. And I checked spark by having a buddy turn the key it's showing spark. I did wonder if it's not sparking under a load though
 
Yamahadude said:
Well I pulled each carb off and took them apart, cleaned the jets, took the floats out and needle valves out. Pretty took them completely apart and cleaned everything and put it back together. It's possible I could have missed something but I think i cleaned them pretty good
Click to expand...

Sounds like you covered it all. How about time and sync? Did you do this after reinstalling carbs?
 
I did not sync them. At first I assumed just pulling them apart and not messing with anything besides cleaning them I would be fine. Does that seem like the problem ? They need to be sync together?
 
Ok here is my .02. Do a compression test. If good, move to spark (which you already did), then move to fuel. For the fuel, I would first squeeze the primer bulb when you reach max rpm, see if that makes a difference. If it does, then check fuel pumps. If it doesn't then check reeds, you can see them easily when carbs are out. If all is good there then move to electronic. Harder to diagnose but if you have compression, spark and fuel then it's somewhere in the ignition system. You will get all the help you need here to troubleshoot. But first is first.

Also, not sure about the 1986 but Yamaha had this safety feature to automatically lower rpm if motor gets too hot. Are your overheat sensors testing properly? Is your buzzer working properly?

It usually ends up being something simple.

Good luck and let us know.

Cheers
F



11
 
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Yamahadude said:
Does that seem like the problem ? They need to be sync together?
Click to expand...

I don't know if you having not timed and synced carbs is the issue....but I do know carbs must be T/S after rebuilding/cleaning, 100%. Just think about it for a moment. For example, lets say that prior to cleaning the jets were gunked up, thereby causing poor performance. In response, you or the previous owner adjust the mix screws to allow for a richer mix to compensate for the lack of fuel passing through jets. Now you clean jets and reinstall, leaving the mix exactly the same as prior to cleaning. No doubt the timing will be off. At least in my mind it will. If you refer to your service manual you will see the indication to time/sync after reinstalling carbs. But of course, I'm not a master yam mechanic. Could I be wrong? Sure. But then ask yourself, which is the worse scenario...you time and sync carbs properly and the result doesn't fix the issue, yet now the carbs are setup. Or you T/S and it fixes the issue.
 
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