iwombat
Captain
- Joined
- Jul 12, 2006
- Messages
- 3,767
I'm having a problem with slowly deteriorating RPMs at wot, as well as increasing problems holding idle.
We're working with a '77 85hp.
Over the summer I've been noticing a decrease in WOT by about 500rpms every 15 or so hours of use. I've also been having to adjust the idle up by increments of 50-100 at about the same interval in order to keep running. It's behaving like it's just wearing out, only really really fast. I've done regular decarbs to no noticeable effect, as well as checked link and sync and made sure the throttle is opening all the way. It's had a recent carb rebuild, and even clogged jets I have a hard time imagining would cause such a gradual decrease.
During this, the compression numbers have remained the same and while low are consistantly in the 88-91 range on what is typically a low-reading gauge.
Plugs are nice and toasty brown all the way across and all look the same.
The boat has foam blocks, and inspection reveals slightly damp, but not waterlogged foam. I can pretty safely rule waterlogging out.
Could this be a failing exhaust gasket maybe? I'm kinda stumped on this one.
We're working with a '77 85hp.
Over the summer I've been noticing a decrease in WOT by about 500rpms every 15 or so hours of use. I've also been having to adjust the idle up by increments of 50-100 at about the same interval in order to keep running. It's behaving like it's just wearing out, only really really fast. I've done regular decarbs to no noticeable effect, as well as checked link and sync and made sure the throttle is opening all the way. It's had a recent carb rebuild, and even clogged jets I have a hard time imagining would cause such a gradual decrease.
During this, the compression numbers have remained the same and while low are consistantly in the 88-91 range on what is typically a low-reading gauge.
Plugs are nice and toasty brown all the way across and all look the same.
The boat has foam blocks, and inspection reveals slightly damp, but not waterlogged foam. I can pretty safely rule waterlogging out.
Could this be a failing exhaust gasket maybe? I'm kinda stumped on this one.