Engine or fuel line problem?

[<Jeffroz>]

1993 Yamaha 225 developed problems with acceleration. Repairs were made on 3 occasions. Plugs and fuel filter were changed, 2 leaky hoses were replaced, and one carburator was cleaned out. After each repair, the engine ran well at first (even sounded better) then the same pattern of decreasing performance took place in the span of about 3h.
1. slight acceleration problems from 15-2400 rpm-drops down to 1100 rpm-occasional at first
2. engine runs well &lt;3000rpm but problems accelerating after slowing to idle-may lag then kick in with a lurch up to 3000rpm, then runs well again
3. problems accelerating from idle become constant but once engine kicks in, continues to run well at full throttle.
4. then acceleration becomes worse-throttle lever can be all the way down and engine sputters and surges-may kick in once or twice up to 3000-3500rpm but then falls back
5. engine stalls trying to push above 1100 rpm-this is when we've taken it for repairs each time-also, a lot of gas seems to be getting used up.

[<Hamfisted>]

Do you have a factory service manual for your motor? If not go to www.YamahaPubs.com and order one. Are the original fuel pumps still on the motor? If so I would look at changing all three out for new ones. Why only one carb cleaned? At the least I would pull the jets out of each carb and clean and inspect them for gum and varnish blocking the orifices of each jet, also spray some good cleaner up into the bowls through the jet passages. I use Amsoil PowerFoam cleaner but if you can't get that then use some Berryman's Chemtool spray (Walmart) and spray the jets and the bowls out. When you have the main jets out inspect the O-ring seals on the ends of each main jet for any cracks, tears or distortion. Install new O-rings as needed (dealer item $5 each...). When you get your shop manual test the coil and sparkplug wire assemblies for proper continuity. The plug wires just screw off the ends of the coils if you need to change them. Sometimes corrosion will build up on the plug wire ends and deteriorate spark voltage causing a weak spark, but honestly your problem sounds more fuel related than anything else. Good luck.


Mike ...... Miami, FL