787 engine surges

[FL_Boater]

This may be kind of hard to explain.

Engine idles perfect. Accelerate boat and pull rpms up to 7000 it surges. It will hit 7 fast, drops to 3 or 4ish and climb back to 7. once it hits 7 it does it again. it repeats this 3 or 4times withing 10 secounds and stalls. always starts right back up. If I do not go WOT and keep rpms arond 5-5500 it will settle down but no good above that.

ideas?

It almost seems like it's cutting the fuel off for a split second every tme it hits 7k

other engine is fine.

 

[Phildoo]

Sounds like carbs.
???

 

[Dr Honda]

Yep... carbs are plugged up, or there is a leak in the fuel line coming in.

Sometimes the RAVE engines will have some mild surging when the valves are moving... but what you are describing is a serious fuel issue.

 

[FL_Boater]

thx guys I'll pull it apart and clean / rebuild them. it's easy enough to do.

 

[6KJR]

Ya Id be fixing that real quick before you end up with a 1000+ repair bill for chunked pistons+