Yamaha 9.9 troubles

[matt167]

My new boat ( 1989 Sylvan offshore ) came with a 2002 Yamaha 9.9 ( T9.9 ELRA high thrust ). Couple issues. It is pumping water but not as good as it should. I put a new pump in it and the pump impeller that was in it was good. The passage is clear. Also it won’t start unless it’s manually choked briefly so I don’t think the primer system is working. I think it’s a pretty high hour motor. Debating repair vs replacement as 9.9’s aren’t terribly expensive in boat terms

 

[boscoe99]

What are you doing to manually choke the motor?

That model does not have a mechanically activated choke plate. It uses a Yamaha PrimeStart system. Automatic fuel enrichment.

If the motor is not over heating then the water pump flow is more than sufficient, no matter what amount comes out the telltale fitting.

 

[matt167]

Literally cover the carb with my hand for a second and it pops off. I know it’s a primer system. I suspect it’s not working. As for the telltale. It dribbles and spits. It’s not overheating but I know it’s not right either. Also throws a bit of blue smoke at startup which is what makes me think high hours.

 

[Mc Tool]

Sounds like its already been cooked . Whats the compression like ?

 

[matt167]

Not sure as I haven’t checked it. I really don’t think it’s down on compression as it does actually run fine and has plenty of power. I just don’t know the break point of where it makes sense to repair vs replace. I’d have no problem putting a brand new DF9.9A on the boat vs replacement if it was going to cost $1,000 to bring it back to life… primer solenoid alone is $100 provided that’s the starting problem

 

[matt167]

I guess it might make sense that it’s been cooked as the rings could be hurt and still run well enough. I don’t have high hopes I guess. I may drop it off at a local shop for a damage report but I won’t be going into any powerhead work. Not worth it

 

[99yam40]

compression is easy to check, and a carb clean & pulling stat and flushing the cooling system with something like Ridlym marine descaler is not that hard either

 

[matt167]

compression is easy to check, and a carb clean & pulling stat and flushing the cooling system with something like Ridlym marine descaler is not that hard either

I would tend to agree 100%. I keep the boat at a storage facility since my yard is a postage stamp.. I can trailer it to my FIL’s for work but I also work full time leaving only weekends and summer is only so long. Paying for a diag may be cheap in the long run

 

[matt167]

The only thing I can think of on the cheap is that if it is condemned, I have a 1986ish Johnson 20hp w/ remote control that I bought for a chugger boat project. It’ll probably need a carb clean and an impeller but it was a solid runner. It’s been on a stand in dry storage since about 2019.