9 replies to this topic

[mattk22]

I have an 87 Mercury 45. It starts up really easily, but when I get it out to my honey hole and shut her off, when I try to fire her back up it is flooded. There is gas coming out of the carbs and rolls down the motor case. Now, every time I take it out of the water, I remove the fuel line so that may be what keeps it from flooding when I start it each time, not sure. This is my first 2 stroke, so I do not know a lot about them. Is it possible that the pressurized gas tank is creating a siphon after I shut the engine off and continues to pull gas into the engine? Could that be a bad fuel pump (I am guessing not since the engine is off)?
It seems to run really good when I have it running. The only other issue I have had is that every now and then when I run it at full power it won't run at full speed. If I hit the electronic choke once or twice while running, that seems to get it going and it flys for 45hp.
Any help would be appreciated.

[lkn4bss]

Sounds like the floats in the carbs are stuck and your not getting the correct amount of fuel at full throttle. since choking it will add more fuel and it runs better. Check the fuel filter, do a compression check. If all good rebuild the carbs. my 0.02!

[Gotfishyfingers?]

X2- Check the float/ float needle,sounds like there stuck.That needle should move freely with the float. Your second issue sound like a jet might be clogged at times. Both are Classic ethanol or just from sitting a while issue. Especially in older model engines like yours. Cleaning the carbs should fix your issues. If your a little unsure about doing it yourself, do a search on youtube. I'm sure there are plenty of videos showing how-to..

[mattk22]

thanks guys, will give it a try

[TomB]

Sounds like a bad fuel pump but your carb float has probably absorbed gas and has gotten heavy leading to flooding when off. Could be both. To troubleshoot I would check the fuel pressure when running but you won't go wrong with a carb rebuild kit and pump kit. Pump diaphrams get old and hard leading to low volume but higher pressure.

[wnybassman]

Power trim and tilt? I had a Johnson one time that if the motor was trimmed all the way down while fishing it would flood itself out. Always had to keep it trimmed halfway up or better.

[BKeith]

Clean/rebuild the carbs. The fuel is leaking buy the needle/seats. Either the needles are not sealing good on the seats or the float level is too high. Be sure the float levels are set right, some Mercs can be a PITA to get them right.

If it's doing it when it's shut off, it's not the fuel pump. No way it can over pressure the fuel and force the needles off the seats when the engine is not running.

It's not a 92 - 95 Johnson v-6, those were the ones with the carbs that flooded out when the motor was trimmed all the way in. If you had any other model doing that, the floats were not set right.

[TomB]

If it's doing it when it's shut off, it's not the fuel pump. No way it can over pressure the fuel and force the needles off the seats when the engine is not running.

Read the whole post. A stiff diaphram and heavy float will cause the starving and hot flood problems he described.

[BKeith]

What ever turns your crank. You'd start with the fuel pump, I'd start with the carbs, and when we both get done, may find out it's an ignition problem. I've never been very good at getting my crystal ball to work over the internet.

I've never claimed to know much about these things, that's why over past 50 years of building and racing just about everything with pistons, and build some pretty wicked outboards now, so I can only go buy what my past experience tells me, that's why I usully don't work on other peoples.

That last line of his post about bogging and having to hit the choke/primer, still pretty much tells me he's got dirty carb problems.

[mattk22]

Seems as if i was just flooding it period. If i started it with it in straight up neutral for one crank, then gave it a touch of trottle for the second crank it fired up every time. I was putting the throttle down a good bit of the way to start it and that was flooding it, and once it flooded I could never get it back. Haven't had it happen since I started doing that new starting technique. Funny the last boat I would drive you had to give it tons of gas to start. Lesson learned.