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Author Topic:   Yamaha 50 problem

McD posted 06-07-2001 04:27 PM ET (US)
Appreciate any opinions on nature of problem with Yamaha four-stroke 50 hp on 1995 Dauntless 15. Motor ran fine Sat. but oil light came on with first start on Sunday and engine ran very rough and stalled repeatedly. There was a noticeable knocking sound. Oil level was fine. Oil light only came on when key turned half way, and went off when engine caught. No smoking and otherwise nothing abnormal. Dealer mechanic is checking but expressed concern about symptons, saying "knocking is not good." Purchased boat just four weeks ago so I'm concerned as well. Thanks for any insight.
B Bear posted 06-07-2001 07:41 PM ET (US)
McD
Did you check the plugs? Pull the plugs and check for residue, if one shows unburnt fuel the pulg may be cracked, or bad, this would account for rough idle and and stalling.
Bear
Clark Roberts posted 06-07-2001 08:41 PM ET (US)
McD, I hope your engine problem is minor! As an old oil burner from way back, I have a tuned ear for any suspicious noise and my advice is always to shut down immediately upon detecting any unusual noise, no matter how slight. Never try to grunt it home... get a tow if possible. Now I've only owned one 4 stroke outboard and that was long ago and far away and the motor was a Lawson (air and water cooled). Remember that 4 strokers have many, many more moving parts compared to a 2 stroker and thus lots of potential sources of noise. Notable is the overhead cam tower, workings and drive (timing) belt. This belt should be of major concern because it drives the cam which activates the valves, etc..etc... and must be replaced per manufacturer's schedule... I'm assuming here that the 50 Yam cam is belt and not gear driven... I'm rambling here but message is that the source of any knock should be determined immediately as you are having the dealer do! I hope to live long enough to develop a tuned ear for 4 stroke noises. Good luck and let us all know the rest of the story! happy Whalin'... Clark... Spruce Creek Navy
McD posted 06-19-2001 12:32 PM ET (US)
Thanks to Clark and Bear for replies and belatedly passing on this response in hopes it may help anyone who encounters similar problem. Turned out to be the fuel connector, the small $10 clip from fuel hose to tank. It was not seated properly and motor was sucking fuel and air. I had suspected this and had removed and reconnected it several times and each time it clicked into place in normal fashion. It had been working fine for a month. But it was off enough to cause some major knocking and stalling. I suspected valve job or worse because oil light kept going on. So did dealer. But he put on new connector and knocking was gone. Offending fuel tank connector was not Yamaha original. It was a West Marine replacement purchased after the Yamaha original broke apart in my hands one day. An original is now back on and I'm carrying a spare. Another boating lesson learned and only a million more to go. McD
jimh posted 06-19-2001 08:12 PM ET (US)
I had a similar problem with the fuel connector on an aftermarket tank.
The tank was a TEMPO brand, and it had a plastic connector. In my case it was a Mercury style connector. It was always a poor fit from day one, and over time the plastic connector cold-flowed into an oval shape instead of circular. The mechanic at the MERC shop who was working on my carburetors pointed this out to me.
I cut it off and replaced it with a metal original equipment connector. That one mates much more easily with the engine's connector.
The cost was trivial: $7.
Go with metal fuel connectors and get the real thing where possible.
--jimh

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Author	Topic: Yamaha 50 problem
McD	posted 06-07-2001 04:27 PM ET (US) Appreciate any opinions on nature of problem with Yamaha four-stroke 50 hp on 1995 Dauntless 15. Motor ran fine Sat. but oil light came on with first start on Sunday and engine ran very rough and stalled repeatedly. There was a noticeable knocking sound. Oil level was fine. Oil light only came on when key turned half way, and went off when engine caught. No smoking and otherwise nothing abnormal. Dealer mechanic is checking but expressed concern about symptons, saying "knocking is not good." Purchased boat just four weeks ago so I'm concerned as well. Thanks for any insight.
B Bear	posted 06-07-2001 07:41 PM ET (US) McD Did you check the plugs? Pull the plugs and check for residue, if one shows unburnt fuel the pulg may be cracked, or bad, this would account for rough idle and and stalling. Bear
Clark Roberts	posted 06-07-2001 08:41 PM ET (US) McD, I hope your engine problem is minor! As an old oil burner from way back, I have a tuned ear for any suspicious noise and my advice is always to shut down immediately upon detecting any unusual noise, no matter how slight. Never try to grunt it home... get a tow if possible. Now I've only owned one 4 stroke outboard and that was long ago and far away and the motor was a Lawson (air and water cooled). Remember that 4 strokers have many, many more moving parts compared to a 2 stroker and thus lots of potential sources of noise. Notable is the overhead cam tower, workings and drive (timing) belt. This belt should be of major concern because it drives the cam which activates the valves, etc..etc... and must be replaced per manufacturer's schedule... I'm assuming here that the 50 Yam cam is belt and not gear driven... I'm rambling here but message is that the source of any knock should be determined immediately as you are having the dealer do! I hope to live long enough to develop a tuned ear for 4 stroke noises. Good luck and let us all know the rest of the story! happy Whalin'... Clark... Spruce Creek Navy
McD	posted 06-19-2001 12:32 PM ET (US) Thanks to Clark and Bear for replies and belatedly passing on this response in hopes it may help anyone who encounters similar problem. Turned out to be the fuel connector, the small $10 clip from fuel hose to tank. It was not seated properly and motor was sucking fuel and air. I had suspected this and had removed and reconnected it several times and each time it clicked into place in normal fashion. It had been working fine for a month. But it was off enough to cause some major knocking and stalling. I suspected valve job or worse because oil light kept going on. So did dealer. But he put on new connector and knocking was gone. Offending fuel tank connector was not Yamaha original. It was a West Marine replacement purchased after the Yamaha original broke apart in my hands one day. An original is now back on and I'm carrying a spare. Another boating lesson learned and only a million more to go. McD
jimh	posted 06-19-2001 08:12 PM ET (US) I had a similar problem with the fuel connector on an aftermarket tank. The tank was a TEMPO brand, and it had a plastic connector. In my case it was a Mercury style connector. It was always a poor fit from day one, and over time the plastic connector cold-flowed into an oval shape instead of circular. The mechanic at the MERC shop who was working on my carburetors pointed this out to me. I cut it off and replaced it with a metal original equipment connector. That one mates much more easily with the engine's connector. The cost was trivial: $7. Go with metal fuel connectors and get the real thing where possible. --jimh