# Yamaha F70 leaking gas/oil?



## Smackdaddy53 (Dec 31, 2012)

Probably just unburned fuel coming from the exhaust which mostly exits the prop.


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## DuckNut (Apr 3, 2009)

Mine drip a few drops of gas when the motor is tilted just right. Then when I launch the water gets inside the cowling and I get a rainbow out the back.

Never caused an issue and I can't recreate the issue so I will wait until it does it every time before I try to find the problem.


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## reedriley8 (Sep 3, 2020)

DuckNut said:


> Mine drip a few drops of gas when the motor is tilted just right. Then when I launch the water gets inside the cowling and I get a rainbow out the back.
> 
> Never caused an issue and I can't recreate the issue so I will wait until it does it every time before I try to find the problem.


wonder where gas would be leaking from? Only reason I’m concerned was that the slick behind me was massive. Definitely not a small leak anymore.


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## m32825 (Jun 29, 2018)

Is there a fuel pump? Has your mpg dropped off lately?


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## GSSF (May 25, 2013)

I think it is either unburned fuel or a little fuel seeping from the engine at a particular tilt angle/trailering, then drips out when the motor is trimmed down.

Keep in mind that just a little fuel or oil can cause what appears to be a massive oil slick. I had an outboard "burp" an ounce or 2 of oil immediately after an oil change (dealer overfilled it, apparently). I was setting the boat down after a run and coming off the throttle and felt/heard the burp. Once stopped, there was oil in the exhaust at the back of the engine but it looked like I dumped 5 gals of oil behind the boat- oil slick was huge. Couldn't have been more than a couple ounces, but looked significant.


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## DuckNut (Apr 3, 2009)

reedriley8 said:


> wonder where gas would be leaking from? Only reason I’m concerned was that the slick behind me was massive. Definitely not a small leak anymore.


Mine leaks from the carb I believe. When it starts, and it starts right up, it has a bit of extra smoke that was not there prior to this happening. It does not take but a few drops to create large slick.

I once had oil drip out of my dipstick tube because I did not have it tight and it too caused a big slick.


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## reedriley8 (Sep 3, 2020)

Thanks for everybody’s replies. Haven’t flushed the lower unit yet, but will this week just to rule it out and see if there’s any water in there. It’s time anyways. If that’s not the case then I’ll start looking for fuel leaks and report back. Definitely seems like it could be just from trailering with outboard at an angle, since the issue only happens at first launch.


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## reedriley8 (Sep 3, 2020)

Found the culprit finally. Leaking injector. Gas pouring out of injector 3 & 4 while running. New o-rings should do the trick. Anyone else run into this issue?


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