Yamaha - after 27 year nap...with VIDEOS

[gofastsandman]

Originally Posted by NoBones

Retired !!! at what 45 ??

I need to find a new profession...

Me too.
Roll eyes.

[Bigshrimpin]

Add in a new set of fuel pumps and you'll have refreshed the entire fuel system on that motor. The ethanol fuel ruins my Merc Fuel Pump Diaphrams. After about 2 - 3 seasons they get hard stiff like potato chips. Just something to consider if your fuel pumps are 27

[77SceptreOB]

Originally Posted by Bigshrimpin

Add in a new set of fuel pumps and you'll have refreshed the entire fuel system on that motor. The ethanol fuel ruins my Merc Fuel Pump Diaphrams. After about 2 - 3 seasons they get hard stiff like potato chips. Just something to consider if your fuel pumps are 27

Thanks for the thought. I actually replaced BOTH fuel pumps three years ago. I know that blows Don's logic that I don't do any maintenance. HeHeHe! I replace the Empellor every 10 years whether it needs it or not...LOL!

[DonV]

OK...I'll give you some credit, it hurts to do that!! But I just thought "maintenance" in your book was putting gas in the tank and two stroke oil in the gas

[Bushwacker]

Jim,

Sounds like that was money well spent! I guess a motor as new as an '88 (my old carb'd motor was a '75 vintage) probably has an oil injection system. However if it just mixes oil with the gas upstream of the carbs instead of injecting oil directly into the bearings and cylinders, it's still basically the same as running premix. If that's the case, running the motor with a plugged carb jet starves that cylinder for OIL as well as fuel, and that can quickly kill a motor!

I had a plugged jet on my old motor one time, but since I was definitely NOT overpowered (~100-105 prop hp on a 20), it was pretty obvious I had a problem, so I discovered it right away. However, one potential issue with a bigger motor that will push a boat over 40 mph is you can have a potentially fatal problem like fuel starvation, but with lots of power available, it's easy to just bump the throttle up a bit and never notice it until it's too late!

If you consider that modern motors are calibrated to run leaner mixtures for better fuel economy, and add e-10 (10% ethanol) gas that contains extra oxygen and burns even hotter if the mixture gets lean, there is not a lot of margin between normal operation and a slight amount of fuel starvation that can lean out a cylinder enough to overheat a piston/score a cylinder, etc.! The older carb'd motors like yours were jetted on the rich side of optimum for maximum power, so it was hard to plug 'em up enough to hurt 'em, but that's no longer true for the modern "clean technology" motors, either 2 or 4 stroke! I'd advise anyone running a modern engine to be very cautious about just bumping the throttle up a little more if it doesn't seem to be running right! While some of the bigger motors have knock sensors or O2 sensors that may detect lean operation, I believe a little extra caution is warranted if a modern motor seems to be down on power! Although I've never had that sort of problem on my E-TEC, my dealer has measured the restriction in the boat's fuel system, I run a vacuum gauge downstream of the fuel filter to check for plugging, and I watch the Throttle Position Sensor reading vs. rpm relationship for anything unusual. One time that alerted me that I had forgotten to pull up the swim ladder, so it seems pretty sensitive! If I was running a 4-stroke and didn't have a TPS readout, I think I'd monitor intake manifold vacuum, as it's also a very good indicator of engine load.

[77SceptreOB]

Thanks Denny. My engine is oil injected and the oil is injected AFTER the carb. Thank God or I would have blown motor 2 years ago. I'm ashamed to say that I have been running on five cylinders for over two years!! 97 hours at around 188 hp. My motor was strong with the compression and I just bumped up the throttle as you mentioned. I got real lucky on this one and learned a lesson. Now with all 6 cylinders and tuned up it runs like a raped ape!!

[NoBones]

Jimbo, you may have earned "Slacker" status on this one...

GFS, you are off the hook...

Humm, I will have to think of a new sub title for 77SceptreOB..

Suggestions are welcomed !

[DonV]

I'm thinking Ken, maybe I'll order up some "pink panty drop" moonshine, which Jim seems to prefer, take a few sips and give it some deep thought.