Yamaha oil problem?

Hipfisher

Cadet
Joined
Jan 14, 2010
Messages
6
Attempted to take the boat out today ('93 200hp 2 stroke). About 5 minutes away from the dock running at 4K rpm I experienced a sudden loss of power and the engine quit. Checked obvious things; no alarms, temp gage normal, drained some fuel from water separator-looked good, oil level in under cowl and console tank good, battery fully charged. Scratched my head for 3 - 4 minutes then attempted to start engine. To my surprise it cranked right up. Ran back toward dock and again at 4K rpm and at about 5 minutes the engine seemed to labor, slow down and quit. I immediately attempted to restart. Cranking sounded very labored, a very slow rrr rrr. I stopped and waited 3 - 4 minutes as before and again it cranked right up. I did notice the temp gage was up about 1/4 scale but came down immediately after running briefly (less than a minute). I idled back to the dock and retrieved the boat on the trailer and called it a day.
I'm inclined to think that I have a oil starvation issue with one or more cylinders which as the engine heats up causes seizure. Any other ideas?
 

ENSIGN

Lieutenant Junior Grade
Joined
Jun 21, 2009
Messages
1,179
Re: Yamaha oil problem?

Sounds like it's running out of gas at high rpm's,clogged pickup,filters,kink in a hose,vent or weak fuel pump.Try a different tank and hose so you can isolate the boat from the motor.
 

99yam40

Fleet Admiral
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Sep 7, 2008
Messages
8,851
Re: Yamaha oil problem?

Sounds like a piston/cylinder seizing. Maybe from lean condition, sounds like you may have a very expensive problem to fix, but you will not know for sure until you do some diagnosing.

I have seen a Dt150 lockup because of no oil in lower unit, which locked up the shaft, but would restart after it sat for a while. It totaled the shaft and the housing.
 

robert graham

Admiral
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Apr 16, 2009
Messages
6,908
Re: Yamaha oil problem?

If motor is seizing then check compression on each cylinder to try to identify problem cylinder. It does sound like a seize, but hopefully it may be a fuel delivery/starvation problem that would be a lot simpler and cheaper to fix. Please keep us posted on what you find out and good luck!
 

rodbolt

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Sep 1, 2003
Messages
20,066
Re: Yamaha oil problem?

have you verified the alarm audible actually works?
oiling issues,if the alarm works and the correct yamaha tach is used,are incredibly rare on that engine.
your describing an overheat.
 

Hipfisher

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Jan 14, 2010
Messages
6
Re: Yamaha oil problem?

Mechanic is coming Monday. I'll post a follow up on what he finds. I'm hoping for the fuel starvation scenario which is obviously the lesser of all evils. It certainty fits. I had a similar problem with a 90 hp Yamaha many years ago. The shop had to change the fuel sending transducer in the tank. In the process they dropped a screw in the tank. There was no filter on the pick up tube. As luck would have it the screw would intermittently get caught up in the pick up tube. The engine would run all day at idle but only about 2-3 minutes on plane. I diagnosed the problem by substituting a portable tank. The engine ran fine on it and saved our vacation. I ended up getting a new tank out of the shop after removing the original tank and asking them to explain the rattle inside!
 

Hipfisher

Cadet
Joined
Jan 14, 2010
Messages
6
Re: Yamaha oil problem?

I believe I found the problem. I remembered there is an under cowl fuel filter and decided to check the connections and condition of the filter. To my surprise I found that the housing was cracked just under the mounting stud. Most likely this allowed air into the fuel line. At idle it wasn't too much of an issue but at higher throttle settings it's probably the cause my problems.
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: Yamaha oil problem?

as your first post said nothing about a fuel leak I dont suspect you found the issue.
that filter is on the pressure side of the fuel primer bulb.
if air can leak in then fuel will leak out when you prime the system with the bulb.
that cracked housing is fairly common if someone gets a bit ham handed when trying to unscrew the filter cup. go test the alarm system.
if rigged correctly this takes about 30 seconds to test the horn.
unplug the emergency stop clip,crank motor.
horn should sound when cranking and no spark should occur.
 

Hipfisher

Cadet
Joined
Jan 14, 2010
Messages
6
Re: Yamaha oil problem?

Sorry for the delay in posting. The mechanic did a compression test and found one cylinder at 40 psi. Cylinder head was removed to expose deep scoring on cylinder walls for that cylinder. After rebuild (boring, honing and all six pistons replaced) during run up it was noted that the oil pump was not providing consistent oiling to that cylinder. The oil pump and all under cowl lines were replaced.
About 6 hours into break-in while trying to avoid an object in the water the prop cavitated. I immediately pulled back on the throttle, however when I tried to get back on plane I could not get any more than 2500 RPM out of the engine. Back to the mechanic. He found that the timing linkage had broken and after repair everything is good again. He did a follow up compression test and all cylinders were within 5 psi. Also the plugs, fowled from double break-in oil, were changed.
We're up and running again. Thanks for all the previous responses.
 
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