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I have a mid 1980's (1984-1986) 75hp Merc on my Montauk and the last few times I've gone to start her up, she ran and then died after a few minutes. Would not start again after priming a bit more...just wouldn't kick over. Then, I adjust the trim, up a bit, and she starts and purrs.

What gives??

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When did the motor start doing that precisely? If you have had the motor since the 80's and it has always done that, well, that would be one thing, but if it just started doing that, it would be another. If it just started doing that, you must have a fuel line pinching at the trim it wont start or dies. Could be something else entirely if it has always done that, you say it's a Mercury...

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Hi Jay,
"Wouldn't kick over" does that mean wouldn't turn over at all or would turn over but not start?
If it's 'wouldn't turn over at all' I'd look at the battery and starter cables.

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The motor is new to me, bought the boat last season, with this motor, the hull is a 1978.

It wants to run, it is not a power/battery issue where it just clicks. It just doesn't want to stay running. This issue just started in the last week.

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Examine the connections and lines at the motor for leaks with the bulb pumped. You may have a line cracking or a fitting clamp-caused crack that only becomes cracked enough to pull air when the engine is at that tilt position. Get somebody to bump the tilt between the problem area and the ok area of the tilt range until you find the stress point or the pinch point. You will find the problem with patience and perseverance. The problem will be located near the engine or on it.

Good Luck

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Makes sense. I'll check on that...

Thank you!

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What happens after you tilt up, start, and then tilt down again, same thing - bogs and dies?

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Haven't tried that yet. But, just took her out for a cruise and ran fine. Didn't trim all the way down to start her and she started up fine and ran fine.

Later today or tomorrow I'll tilt all the way down again to start and while running to see what happens....

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Jay, I had a similar problem years ago with the 1975 Johnson 135 I had on my boat at the time. Due to repeated tilting, and perhaps some original wire issues while the engine harness was being manufactured, I had an open wire. First the problem was intermittant. Then finally, it would not start/run at all. That at least made it easy to troubleshoot. Can't remember if it was the ignition wire or the start solenoid wire, but when I bypassed them and connected a jumper wire direct from ignition switch to engine, the problem went away. Next step was to remove the wiring harness and do a continuity check on the wires. Yep, found one wire open. Then the issue was to find out where. At that point, suspecting the wire was due to tilting or steering and wire harness bending, I cut away the wire harness thick rubber chafing protective cover. And there it was, a broken wire. Some soldering in of a new jumper to bridge the gap, and the problem was solved and never returned. You may have a similar issue just beginning.

I recommend that if you ever have the start issue again, without changing the trim of the engine, bypass that particular wire/circuit from ignition switch to engine. If it is immediately cured, you know what is wrong and what the fix is.

Good luck!

Al

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He says it turns over when he has his problem, indicating that the starter is working as it should. I don't see how it could be anything in the wiring if the motor is turning over (starter working) and the neutral switch is working.

I still think it sounds like an air leak in the fuel system.

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Correct, it's not a starter/ignition/battery issue as the motor does engage when the key is turned. The fuel issue sounds more accurate. It actually idles better when not tilted all the way down as well.

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Here's my take.

Tilting the engine up or down will not stop the motor from starting or stopping UNLESS, there is a loose wire.

Sounds possibly like a ground wire in the harness is loose or rubbing on something which then kills the motor or won't allow it to start.

Same principle applies with the "Kill Switch".
This grounds the magneto and will not let it start.
So, check your Kill Switch also.

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I am probably wrong, sorry.

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I don't have a Kill Switch...that I know of. Joe, would this loose wire allow the engine to sputter and cough . Like I said, it wants to start, just wont. Not a power issue where the ignition just clicks...isn't that what a Kill Switch would do, just "click"??

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You don't have a Safety Lanyard attached to a Kill Switch?

If the safety lanyard is pulled, the motor will crank but not start.
Also, if the motor is running and the lanyard is pulled, the engine will die.

All motors I have had had a Safety Lanyard or Kill Switch.


I was basing my thoughts on your first post.

If your motor is running but sputters and coughs, then it may be something else.

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Jay, it's probable you do have a kill switch - I looked at the picture of your console, but it's too blurry to make out where things are.

Maybe the previous owner lost the lanyard and clip and jammed something in there to hold it closed. Look for something near the trim switch that you are bumping when you trim the motor. Or it could be that your previous owner jumpered the connection (a really bad idea) and there is a loose connection in the circuit that is affected by the motor position.


Tim

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Is it flooding? Maybe there is some gunk in a carb causing the float to stick and flood. When it's tilted down, maybe the fuel puddles in the cylinder but when it's tilted up a bit, it doesn't flood as bad. That's just a guess. I have a 1989 Mercury 90 2-stroke 3-cylinder with a gunked carb that acted like that.

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That's possible. It's been starting and running fine as I just don't trim all the way down now. "Hey Doc, it hurts when I do this..."

And, there is no kill switch, lanyard or evidence of either one anywhere.

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Jay, like Cape Fear stated, I think it might be related to the float level. I used to work on outboards from that era years ago and I witnessed that all the time. Usually a simple cleaning will take care of it but that was before the Ethanol days so you might need to invest in new floats, needle valves, etc.

I have a 1991 Suzuki 30 HP on my 13' Whaler and I experienced weird carb issues and I cleaned them out only to find the same issues. I thought it was possibly an ignition problem but I went ahead and bought a carb rebuild kit and replaced all floats, needle valves, seats, gaskets, etc and she is running like her old self now. Our old engines were just not made with Ethanol in mind.

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My mercury 115 1980+- was very easy to flood, if you choked it just a little too long you had to wait it out and then start. I bet that you are letting the excess fuel run out of the carbs when you tilt up [it does not take much tilt for this to happen. Try starting in the down position but choke less than you are currently doing and see what happens. It could also be a small blockage in a idle jet. Mercury makes a 3 part additive that is 1 oz /5 gallons of gas. Use step #2 it is to clean fuel system and carbs. I just started last week with it and it helped the low idle on my Yamaha 70 2-stroke after about 10 gallons.

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So, we are back to this being fuel related? Hmmm...I wonder what it actually was?