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15 hp Yamaha 4 stroke, misses high rpm. Installed new gas…

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15 hp Yamaha 4...

15 hp Yamaha 4 stroke , misses high rpm

Mechanic's Assistant: Sometimes things that you think will be really complicated end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so the Marine Mechanic can help you best.

Installed new gas line,seafoam in fresh gas. plug tips whitish color

Mechanic's Assistant: Is there anything else the Marine Mechanic should be aware of?

Took carb off, tore apart every thing looked clean

Submitted: 23 days ago.Category: Boat
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5/30/2018
Marine Mechanic: Jason, Marine Mechanic replied 23 days ago
Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 17,446
Experience: Degree in Marine Technology. Gas and diesel marine mechanic.
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Hello my name is ***** ***** am I speaking with? I read what you wrote. Can I start by getting the model number on the engine as it reads on the ID tag?

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Customer reply replied 23 days ago
jeff
Marine Mechanic: Jason, Marine Mechanic replied 23 days ago

HI Jeff. Can I start by getting the full model number on the outboard as it reads on the ID tag.

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Customer reply replied 23 days ago
f15elhx
Marine Mechanic: Jason, Marine Mechanic replied 23 days ago

okay got it. Is there any kind of story or history to this outboard, have you ever personally seen it run correctly? Is the fuel tank for the outboard a plastic portable type of tank, or is the tank built into the boat? When you cleaned the carb, did you clean it by hand, or did it go into an ultrasonic machine?

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Customer reply replied 23 days ago
ran fine,ran gasout of it, winterized it, then recently started and ran, plastic tank, cleaned carb by hand no gunk inside
Marine Mechanic: Jason, Marine Mechanic replied 23 days ago

Got it. You said something about the spark plugs being white. Do the plugs look clean, almost like they are new? Or do they have some brown to them on the inner insulator?

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Customer reply replied 23 days ago
they are new
Customer reply replied 23 days ago
just tips are whiteish
Marine Mechanic: Jason, Marine Mechanic replied 23 days ago

Got it. Other than the carb have you done any kind of diagnostics? Have you checked the compression? Checked the fuel pressure?

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Customer reply replied 23 days ago
I pulled fuel line off pump turned it over squirted fuel pretty good. finger over plug holes good blast of air on both cylinders
I did noticed oil smelling like a little fuel was in it though
changed when winterized
Marine Mechanic: Jason, Marine Mechanic replied 23 days ago

Squirting a little fuel at turn over versus making 3 to 7 PSI at full throttle are 2 different things. I guess my last question is this. I do not know what you have for tools or ability, did you have any specific questions that you wanted a direct answer to, or would you prefer if I explained what we would do in the shop, going step by step, covering all bases?

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Customer reply replied 23 days ago
I would probably go with checking fuel pressure because the fuel system is clean but its running lean. Ill start there thanks for the chat
Marine Mechanic: Jason, Marine Mechanic replied 23 days ago

This engine uses a plunger style pump. When the pumps diaphragms get a hole in them, they will still pump fuel but they will also leak fuel directly into the engines crankcase (where the oil is) So if the crankcase is filling up with oil, that is a good sign the fuel pump has a pinhole in it's diaphragm. Does that make sense. I do want to make sure you are happy with my service before you go. If you had a further or more specific question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.

Thank you
Jason

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Customer reply replied 23 days ago
Great advice Jason. since crank case oil smells of fuel then it is the pump, Thanks again!
Marine Mechanic: Jason, Marine Mechanic replied 23 days ago

You are very welcome. Please do not forget to select a 5 star rating for my service. Happy boating! -Jason

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