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Author Topic:   Mystery 90 HP Yamaha Power Loss

dmrose posted 01-23-2007 02:55 PM ET (US)
Several months ago I made about a 35 minute run to some fishing grounds on Puget Sound in my 17 Montauk with a friend. After a fews hours of fishing we started the return trip and after about 10 minutes into the journeys, my 90 hp 1985 2 stroke Yam lost power and quit on me. I spent about 15 minutes inspecting the motor and trying to restart it but no such luck. About 2 hours into my journey home on the kicker I tried starting it again and no joy once more.
I'd had plenty of gas but the oil reservoir was about 1/4 full. I usually check it every other time out and the last time it was nearly full. No overheat alarm ever sounded and my tell tale stream remained strong.
Today I put it in the water and the engine ran great for about 20 minutes at full cruise (4000 rpm). We checked the plugs and compression and all seemed normal. Any ideas what happened? Does this motor have a low oil shuttoff that just needed to be reset? Any help would be great!
Dylan
Tom W Clark posted 01-23-2007 03:34 PM ET (US)
Dylan,
What about a fuel restriction? What type os tank(s) do you have in your Montauk? Any filtration system? What tank did the kicker draw its gas from?
dmrose posted 01-23-2007 04:51 PM ET (US)
Tom,
It certainly acted like fuel restriction. The kicker is running out of a 6 gallon Tempo plastic tank and the main is running out of a 12 gallon Tempo. The tanks were both new as of about 10 or so times out ago, as well as a new fuel line for the main.
A restriction could have occured in the connector between the hose and motor. Any way to test that connector or should I just get a new one?
Dylan
Teak Oil posted 01-23-2007 04:55 PM ET (US)
Was the main tank "sucked in" or collapsed at all?
Tom W Clark posted 01-23-2007 05:24 PM ET (US)
Dylan,
A closed vent on the tank could have caused a temporary vacuum and killed the motor.
Other things can cause a temporary fuel restriction too like a kinked fuel hose, debris wrapped around the end of the fuel pick-up in the tank, a clogged fuel filter, etc.
dmrose posted 01-23-2007 05:59 PM ET (US)
The fuel tank was not sucked in or collapsed and the vent was open. I'm going to continue to think along the lines of fuel flow (or lack thereof), I will research changing out my fuel filter and or fuel seperator. Thanks for the help! I'll let you know what I find.
Dylan
Chuck Tribolet posted 01-23-2007 07:39 PM ET (US)
How about an air leak? If the engine is sucking in air
it won't run. And an air leak won't leak gas if it's at
the top of the tank or at the engine.
Step 1: tune up the kicker.
Step 2: go boating.

Chuck
jimh posted 01-24-2007 01:01 AM ET (US)
Please read
A Primer on Primers
http://continuouswave.com/whaler/reference/primer.html
for some good insight on fuel system problems associated with the tank, primer, and hose.

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Author	Topic: Mystery 90 HP Yamaha Power Loss
dmrose	posted 01-23-2007 02:55 PM ET (US) Several months ago I made about a 35 minute run to some fishing grounds on Puget Sound in my 17 Montauk with a friend. After a fews hours of fishing we started the return trip and after about 10 minutes into the journeys, my 90 hp 1985 2 stroke Yam lost power and quit on me. I spent about 15 minutes inspecting the motor and trying to restart it but no such luck. About 2 hours into my journey home on the kicker I tried starting it again and no joy once more. I'd had plenty of gas but the oil reservoir was about 1/4 full. I usually check it every other time out and the last time it was nearly full. No overheat alarm ever sounded and my tell tale stream remained strong. Today I put it in the water and the engine ran great for about 20 minutes at full cruise (4000 rpm). We checked the plugs and compression and all seemed normal. Any ideas what happened? Does this motor have a low oil shuttoff that just needed to be reset? Any help would be great! Dylan
Tom W Clark	posted 01-23-2007 03:34 PM ET (US) Dylan, What about a fuel restriction? What type os tank(s) do you have in your Montauk? Any filtration system? What tank did the kicker draw its gas from?
dmrose	posted 01-23-2007 04:51 PM ET (US) Tom, It certainly acted like fuel restriction. The kicker is running out of a 6 gallon Tempo plastic tank and the main is running out of a 12 gallon Tempo. The tanks were both new as of about 10 or so times out ago, as well as a new fuel line for the main. A restriction could have occured in the connector between the hose and motor. Any way to test that connector or should I just get a new one? Dylan
Teak Oil	posted 01-23-2007 04:55 PM ET (US) Was the main tank "sucked in" or collapsed at all?
Tom W Clark	posted 01-23-2007 05:24 PM ET (US) Dylan, A closed vent on the tank could have caused a temporary vacuum and killed the motor. Other things can cause a temporary fuel restriction too like a kinked fuel hose, debris wrapped around the end of the fuel pick-up in the tank, a clogged fuel filter, etc.
dmrose	posted 01-23-2007 05:59 PM ET (US) The fuel tank was not sucked in or collapsed and the vent was open. I'm going to continue to think along the lines of fuel flow (or lack thereof), I will research changing out my fuel filter and or fuel seperator. Thanks for the help! I'll let you know what I find. Dylan
Chuck Tribolet	posted 01-23-2007 07:39 PM ET (US) How about an air leak? If the engine is sucking in air it won't run. And an air leak won't leak gas if it's at the top of the tank or at the engine. Step 1: tune up the kicker. Step 2: go boating. Chuck
jimh	posted 01-24-2007 01:01 AM ET (US) Please read A Primer on Primers http://continuouswave.com/whaler/reference/primer.html for some good insight on fuel system problems associated with the tank, primer, and hose.