93' TX Yamaha 250

[Rossgon]

Hopefully someone can help me with this.

I've had this engine on my 25' Grady White for 2 years and started to have a problem. When cruising at 4700 RPM's the boat on occasion will loose RPM's...Like the throttle is slipping....and throttle down to 4500....I just had my fuel filters replaced and had an annual on it and the mecanic didnt find anything wrong. I took it out today and it did the same thing....Anyone know what this is or what steps I should take next...

[Deepwatertroller]

While your running at full throttle and rpm's drop, go back and pump primer bulb.If engine rpm's increase, replace primer bulb/fuel line. I had this happen on my 94' 250 and it drove me nuts. Hopefully it works for you.

[jb123]

try pulling each plug wire while running,listening for the rpm change or none.
also try with air breather off, chocking each throat with your finger, again listening for the change to try to isolate the issue.
Never really heard of the 250's carbs clogging but im sure its possile.
you can also run it at night looking for any errant spark aound the coils and lead wires.
How old are your fuel pumps, may want to consider replacing if older that a few years, along with your motor filter.
run with an auxillary tank to see if it helps or not to rule out the supply side.
Lastly, air leaks are a real pain to figure out and fuel line is cheap.

[ March 13, 2007, 08:44 PM: Message edited by: jb123 ]