1991 Pro V200 power loss

[dilb1229]

Starts and idles fine, but have had a sudden loss of power.
Last season, it ran great until the last run, when the power loss occured. This season, it started out the same, but midway through the first run, full power resumed. Stayed this way the next time out until just before returning to the dock, when the power loss returned. Has stayed that way since.
Doesn't seem to miss, but there is just no power. A little vibration at low end, but as it builds speed, the vibration goes away. It tops out at about 3/4 speed (4500 rpm).
Am relatively convinced that it is not the fuel pumps (replaced last summer), fuel filters, or the carbs because it went from poor to great and back to poor. Is it the CDI module (is this 'limp' mode)? In process of trying to check it now. Any tips on what to check and how? Other possible causes?
Many thanks.

[jb123]

why are you so positive that your carbs are not dirty and clogged? that is the exact description of carbs with sediment in them. take a look at the price of a cdi compared to 2 hrs of your time to clean carbs.

[Ken]

dilb,
I don't think your motor is going into "limp" mode, also known as rpm reduction.
When rpm reduction occurs, the alarm will sound and the motor shakes violently because the CDI is cutting back on spark - will cut back down below 1000 rpm until you back off on the throttle, and then the motor will idle normally.
I tend to agree with jb that you have a fuel problem. Next time the motor drops rpm, have someone check the primer bulb - if it has collapsed, then there is a restriction from there on back to the fuel tank. If not, then try pumping the bulb several times - if the rpm picks back up, then you have a fuel pump problem. If not, then the carbs are probably clogged with gum/varnish. Try a shock treatment with SeaFoam or RingFree - sometimes that works. If not, then remove all jets that you can get to and squirt some BerryMan's Chemtool into the orifices. If that does not help, then time to tear down those carbs and install a carb kit.
Good luck [img]smile.gif[/img] ,
Ken K

[dilb1229]

Thanks to both of you. It appears to be in the fuel line or the tank vent. I did remove the carburetors and shot some cleaner and compressed air through them although the looked clean. I also swapped out the fuel pumps with a couple of others I had on hand, changed the plugs and replaced the water-separating fuel filter. It ran better, but pumping the primer bulb did make a difference. I will be changing it out and blowing some air back through the fuel line and making sure the vent is clear. I think that will do the trick. Thanks again. - Steve