1998 BF90 oil or fuel slick on the water

RoGun_Mako171

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My 1998 Honda BF90 outboard runs great and there is no water in the gear oil or engine oil. On occasion, after running the engine for a while and stopping it, an oil slick develops around the stern of the boat. I think it's fuel because there is a slight hint of fuel smell when I scoop some up and smell it, but I am not sure. This occurs when the engine is down, this is not related to tilting the engine. Does anyone have any ideas why it would do this? Is it normal for a carbureted 4 stroke outboard to leak fuel into the water?
 
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ahicks

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No, it's not normal. Have you had the cowl off to have a look around inside looking fir "wet" areas? Is it possible a fuel line is leaking?
 

RoGun_Mako171

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Thank you for the advice. I'll have a closer look. I just purchased the boat/engine last year. I'm thinking it's time for a carb cleaning and perhaps new fuel lines.
 

RoGun_Mako171

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I carefully looked over the fuel lines with the engine running and after I stop it, but found no leaks. All of the lines look good from what I can see. I did notice a bunch of oily residue all around the inside of the lower cowl and dirt stuck to it, as if there was oil spilled when someone changed the oil and didn't clean it up well. So I de-greased it best I could and washed it out, hoping it was just accident and there is no leak.

Going back to the possible fuel leak, what would be the symptoms of a sticking float? Would fuel leak if a float was sticking? What would be other symptoms of a sticking float? I'd like to push my carb cleaning to next season if possible...
 

ahicks

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If it's running right (making full power, easy to start, good idle) leave it alone! Look into running fuel treatment any time its not going to be run for mare than a couple of weeks, or drain the carbs.
 

RoGun_Mako171

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Good advice, thank you for the input.

I'm hopeful that I have solved my oil slick issue with the lower cowl cleaning. If not, I'll remove the cowl and try to track down what is leaking when it is leaking.
 

RoGun_Mako171

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I saw a small oil slick when I had the engine tilted up, seemed to be coming from the Power Trim and Tilt. Is there a way to check for water in the PTT oil without removing it?
 

RoGun_Mako171

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It's the PTT. I heard a pressure leak when working the PTT this morning when it was out of the water and could see a seal leaking. Looks like I will be rebuilding it.
 

RoGun_Mako171

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Wow! $300 for o-rings, back-up rings, oil seal, filter, oil and tools to rebuild the PTT... and there are 2 o-rings that I can't find for my serial number range. Does anyone have experience with the PTT rebuild? I'm wondering if I should assume water has contaminated all 3 cylinders and should buy everything or only focus on the leaks in piston rod B. Any input would be appreciated.
 
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