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I have a 1992 150 HP Mercury Black Max (oil injected) outboard on my boat. It has been running fine until the last two trips. It starts fine and RPMs are not an issue while it is out of gear. When I put it in gear it will not gain adequate RPMs (only goes up to about 3,000 and should reach around 4,500 to 5,000). If I quickly shift it back to neutral, while it is in gear, it will die. I pulled the plugs and they looked fine, but I will replace them anyway. I am also replacing the fuel filter. Are these likely my problem or should I be considering something else?
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Are you using ethanol free gas? I know you run SeaFoam but using gas with ethanol could be the problem. If that isn't the problem, you could have an injector issue. Have you contacted Mntcat about this problem, he might be able to help.
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[quote wiperhunter2]
Are you using ethanol free gas?
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No. I ran ethanol free gas for over a year when I first got the boat, but got tired of having to make special trips to fuel up and got frustrated with the high price they charge for it. I have been adding Marine StaBil and a Mercury additive.
[quote wiperhunter2]
Have you contacted Mntcat about this problem, he might be able to help.
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Nope
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If the gas is the problem, then it might have been worth it to drive out of your way to get it but marine stabil should have worked. Have you called Lee to see what he thinks? A lot of time when I call him, he will give me advise over the phone or at least tell me what it could be. You never know for sure but as I said, it could be clogged injectors or the injector pump. If its either one your going to be taking it to the shop but one thing I read on the SeaFoam directions or maybe it was their web site, is that it can help clean injectors if you run a large amount of it through the system. Not sure how much but it might be work a shot, if you can fine some more info about it.
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[quote wiperhunter2]
Have you called Lee to see what he thinks?
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I try not to bother professionals while they are working. I sent him an email explaining the issue and asking how far out he is on work, in case I have to take it in, assuming it is no better on Tuesday, when I fish Jordanelle. He and/or Dixie have been good to reply to my emails.
[quote wiperhunter2]
...one thing I read on the SeaFoam directions or maybe it was their web site, is that it can help clean injectors if you run a large amount of it through the system. Not sure how much but it might be work a shot, if you can fine some more info about it.
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The Mercury product I am adding is "Quickleen", which is an "Engine & Fuel System Cleaner".
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I recently had a simular but slighty different problem. 2011 115hp four stroke. So not sure if it relates/crosses over to the 90s Mercurys. Anyways it ended up being the float in the fuel module (part mechanical/part electrical item). (Mine was the 4th or 5th they had to replace last week alone at the BPS/Tracker Marine in Vegas...)
I thought 100% for sure my issue was electronic and it ended up being fuel related for the most part. Tough to troubleshoot marine motors these days without the special computers/connections to read what is going on inside.
The reason I mentioned it is that you said as soon as you came off throttle it died. IMO that starts to sound like too much fuel/flooding somewhat. But again one never knows with marine engines. Could be spark related.
Another item to ponder is the power packs. More of a 90s Mercury item that is semi common to go/have issues with.
I run Star Tron Enyme Fuel Treatment in every drop of gas that has gone into my boats fuel tank since new almost 5 years ago. Doing it's job as far as I can tell. Other than this last issue always purs and I have ran 10% ethanol fuel through it since day one since non-ethanol fuel in Vegas is non-existent. Same with my 4 year old camping generator and lawn motor. All start first pull/crank.
Tom
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I'm not a pro by any means, but this sounds like a carb issue to me. Secondly, I would guess fuel pump. For the money and time you'd spend trying to figure it out, I'd get it over to Lee @ Lee's Marine. He's THE Merc Master.
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I couldn't agree with you more. Lee is out about 1 1/2 weeks on repairs and I want to participate in the DAV event and if I take it to him it will cut it really close, but that is the direction that I may go and certainly the direction that I want to go.
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I would definitely put new plugs in it and try it out at a close lake , it is probably a carbed engine and most likely you have one carb that has a pugged jet knocking your rpm down .
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I put new plugs and a new fuel filter in it. I will be trying it out tomorrow at Jordanelle.
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Hope you had a good day on the lake...catching fish that is! Let me know if you still need help with your motor.
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I had to call in sick so I could go to Lake Powell!
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Fortunately, the outboard ran fine at Jordanelle today. Apparently, changing the plugs and the fuel filter made a difference. I will keep you in mind for future repairs.
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Kent, I had the same problem with a car motor v8. It would run great setting in park, rev up fast idle just fine and then put it in gear and go no faster then 20 mph. It turned out to be the plug wires.
I would also check you fuel lines for vacuum leaks at the fittings.
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Hi Chuck,
Thanks for the advice. Replacing the plugs and the fuel filter helped some, but it still isn't 100% right. It also almost-always beeps, instead of starting, when I turn the ignition. A boat mechanic is going to look at it tomorrow.
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It sounds like my Mercury a few years back. Mine was leaking gas and sucking in air. I had a O-ring that went bad in a gas line where it goes into the fuel pump. Pull the cowling and see its wet anywhere. If it is find the line from wet to dry and start looking for the problem there. Just a thought. Good luck
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Thanks for the suggestion and we couldn't find any leaks. This is frustrating to me and also the mechanic who is looking at it this very moment.
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