Engine bogging in and out past half throttle

[rryanstrickland]

I figured it out!!! I finally figured it out!!!!!!!!!!

Well after lots of help from you guys and my own trial and error...I FIGURED IT OUT!
So I was on the lake Friday and I had the same problems from the left engine when I would try and go above half throttle or so. (the engine would rev up as it is supposed to and then die down to about 4K rpm, then back up, and back down....)

I decided to look at the fuel bowl filter again. There was a little bit of trash in it, but not much. So I cleaned it and put the filter back in and tightened the bowl back in place REAL TIGHT. After that it ran like a top! Haulin A$$!!! This thing will fly!

Well, I immediately thought it was the fuel filter that was clogged just a tiny bit causing the problems. The next day, (Saturday), I figured it would be a good idea to thoroughly clean both filters. When I took both of them off I realized that the "left" engine fuel bowl WAS MISSING THE O-RING!!!!!!!!!!!!!!!!!!!:ack:

This whole time it must have been sucking air into the fuel system through the fuel bowl not having an O-ring!!!

Lessen learned my friends! :cheers:

 

[deepdiver]

I'd have to say those measurements are really strange. The output from the rectifier should be positive. Negative is really wierd. Retest... ensure your neg black leads are attached firmly to engine or battery ground. Red lead is connected to battery. Is the battery connected? It should provide a 12.4 VDC baseline. Then the rectifier adds to that depending on revs.
This whole rectifier thing as described by Timmy seems strange. The rectifier is basically a half wave diode array converting ac to dc. Maybe your ignition is being interfered with... I just doubt it. At the same time your measurements are strange.

 

[deepdiver]

Thanks Ryan for the info re fuel filter O-ring. We all need to check that it is in place and tight. I'll be checkin mine too!

 

[toppo72]

hi im having the same prob , i unpluged the red wire and my ski runs good , but when i check the batt when running its still charging the batt, is this wat happens ?
thanks mark

Chicks...you could've followed it to the "plug", then pop the wire out. If still problem, and since, we dont know ur situation, have you cleaned/rebuilt carbs lately?

rryan...you mentioned you went thru carbs, so I mentioned about the rectifier. You can, if you think the carbs are good, is to replace the o-rings in the inline filters.

Heres the cinerio about the rectifier...The rectifier/regulator box does two things. It recieves AC voltage generated by the stator coils through the yellow wires. It then converts that AC power to DC power using the rectifier portion. The red wire sends back to the battery, regulated DC voltage to keep your battery charged while riding the ski.
When the rectifier quits working, that red wire is sending AC voltage to the DC battery. Your ignition runs off DC power as it is a DC CDI ignition. When AC is sent, it interferes with the DC CDI. If you can picture the static your car radio has when under high power lines you can understand how the AC effects the ignition.

A magneto produces very little voltage at lower rpm and more voltage at higher rpm. That is why the motor will start and run decent at lower rpm, but run very ragged at higher rpm when the rectifier is shot.