1958 Johnson Seahorse 18hp leaks lots of fuel out of the exhaust.

[dwittig33]

while trying to start it will backfire a ton of fuel out of the exhaust, also when i tip the motor up it drains a bunch out as well. when i finally get it started it will run like it always has, and even start back up after its warm. getting tired of dumping fuel in the water though. any thoughts? thanks

 

[derek4325]

That's the nature of the beast. Those engines typically dump a certain percentage of unburnt fuel out the exhaust and into the water. You most likely see green sludge oozing out the exhaust as well when you pull it out of the water. That is exhaust, fuel, and water all mixed into one. Is the engine actually backfiring? If so you may need to get the throttle/ carb/ magneto linkages in sync. Also the obvious like spark plugs

 

[Roberthill]

Try decarboning , there may be a buildup .

 

[oldboat1]

Sounds offhand like a float issue. It's possible to install the buggers upside down.

They are a little cleaner than you describe, and should be no backfiring at startup. I would check the float and float needle, and try adjusting the mix needles (See the stickies up at the top of the forum.)

 

[dwittig33]

thank you all for the responses. I have had this motor for 7 years and it is certainly not normal fuel dump. This year in particular I've noticed more fuel/oil leakage, than previous years combined.

It doesn't backfire when the motor runs, but just while trying to start it every now and then. So i'm not sure if that would be considered an actual backfire, though i think my linkages are fine being its ran for years without me changing anything.

My spark plugs have good spark and when i finally do get it started it runs as good as ever.

i'm not sure how to decarbon, but i'm sure the google machine will help with that.

The float is the correct side up and the needles are adjusted correctly (I've done a lot of work on the carburetor in the past). The float could be sticking, but the primer bulb (2 line pressurized tank old style) does stiffen up when priming, so wouldn't that mean the float is shutting off correctly?

I've had a lot of problems with this motor in the past, and most of them come back to the carb, but this time i do think it is something internal being that i pulled the carb a couple times already and haven't found a problem yet. However my knowledge of the internal workings is pretty limited.

i have noticed that after priming the motor and pulling the rope several times it does drain the carb bowl. So i'm pumping a lot of fuel through the motor, for some reason it doesn't fire and works its way out the exhaust. I hope cleared the water a bit to this muddy question. any more advice will be appreciated.

 

[valvebounce]

Sounds like a flooding issue.If the float is a sealed metal one,it could be punctured.The float cut off pin may be worn and jamming,or the mechanism may have stressed over the years and twisted or altered the float cut off level.
The reason it doesn't fire up is probably because it is flooding.(similar to too much choke)
Logically,it can't be anything but a flooding issue.
I had a 2 stroke 500cc motocross bike with a similar problem,it had twin floats,one of the floats was punctured.
If it was my problem,i'd get a new float and mechanism,and a new float cut off pin.