Gas leak when motor is trimmed up?

BigJeff

Cadet
Joined
Apr 13, 2011
Messages
23
I have noticed that when I trim my motor up completly or even most of the way some gas seems to leak out of the motor onto the rear splash pan, I have not found any bad hoses so I am imagining it is something in the carbs, I did replace a missing gasket on one last year but this problem still continues. And as I mentioned I do not have any issues when the motor is trimmed down.



96 Merc 135hp
Parts Listing:

http://www.crowleymarine.com/mercury-outboard/1678.cfm

Service Manual:

http://1manual.com/Mercury manuals...52r3/cover.pdf
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,981
Re: Gas leak when motor is trimmed up?

It is normal for some fuel to leak out of a carb bowl when you tilt the motor, past the trim zone. In your case it gets trapped in the airbox until you trim down and then it runs into the cowling, right?
 

BigJeff

Cadet
Joined
Apr 13, 2011
Messages
23
Re: Gas leak when motor is trimmed up?

Not sure how much is getting trapped in the cowling I will try to watch later tonight when I run it and then trim it up. It usually drips out into the back transon area of the boat. and not much but may be an .5 oz or so. It would make sense to me that if the carbs has gas in them then that would leak out if I trim up all the way but I don't remember my previous merc doing it.
 

SingleShot

Petty Officer 2nd Class
Joined
Jun 24, 2003
Messages
113
Re: Gas leak when motor is trimmed up?

My 2003 125 has done this for years. It seeps out as posted above. In the garage I just leave it trimmed down.
 

diehardmason

Seaman Apprentice
Joined
Sep 9, 2011
Messages
30
Re: Gas leak when motor is trimmed up?

I have a 1996 125 and it does the same thing. Was wondering if that was normal. Maybe its common to the similar sized motors?
 

bajaunderground

Lieutenant
Joined
Apr 18, 2008
Messages
1,401
Re: Gas leak when motor is trimmed up?

I have a 200 and it does the same thing when tilted. It could be normal or it could be a stuck float or little pieces of whatever in the jets??? When was the last carb rebuild? I rebuilt mine last summer and most of the leaking stopped.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,710
Re: Gas leak when motor is trimmed up?

Let's take a bottle of windshield washer fluid; the blue stuff. Use it up and take that bottle and use it for water to dilute your fire ant spray. If you turn the bottle upside down, with water in it, it will gurgle out at the rate that the air is replaced for the fluid that left.

Carbs have a venturi jet in the carb air intake whereby the "wind" going by sucks fuel up from the carb bowl. You have a carb full of fuel, a venturi jet below the level of the fuel in the carb and wala. You have leakage. Simple solution. Don't leave your engine tilted up longer than is necessary to support your fun in the sun.

HTH,

Mark
 

SgtDeadeye

Cadet
Joined
Jul 26, 2011
Messages
28
Re: Gas leak when motor is trimmed up?

BigJeff,
I am by NO means any type of expert, but what I was TOLD was that some gas leaking is normal, but many times its because the float level of the carbs is set too high? Not sure when you last checked those, but it might be worth a look.

Happy Boating

I have noticed that when I trim my motor up completly or even most of the way some gas seems to leak out of the motor onto the rear splash pan, I have not found any bad hoses so I am imagining it is something in the carbs, I did replace a missing gasket on one last year but this problem still continues. And as I mentioned I do not have any issues when the motor is trimmed down.



96 Merc 135hp
Parts Listing:

http://www.crowleymarine.com/mercury-outboard/1678.cfm

Service Manual:

http://1manual.com/Mercury manuals...52r3/cover.pdf
 

BigJeff

Cadet
Joined
Apr 13, 2011
Messages
23
Re: Gas leak when motor is trimmed up?

I will have to look at the level to see if it needs to be adjusted. Sounds like a carb rebuild would be good for the old girl. Took her out yesterday and she ran great. Andrea the fish where biting.
 
Top