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My Honda bf40 revs up and down during idle. 1999 Honda bf…

My Honda bf40 revs...

My Honda bf40 revs up and down during idle

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.

1999 Honda bf 40. Cleaned carbs,tank,new plugs,fuel filter, fuel line from tank to engine,new water pump,new water separator. The idle will be good and then will rev up to 2000 to 3000rpm then back down. We took it for a run and would bog down at about 1/2 throttle. I just got boat and it had sat for a while. Refilled with non ethanol fuel

Mechanic's Assistant: Sometimes boat issues seem like they'll be really complicated, but end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Boat Mechanic should know before I connect you? Rest assured that they'll be able to help you.

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9/16/2021

Marine Mechanic: Ted G., Marine Mechanic replied 1 year ago

Ted G., Marine Mechanic

Category: Boat

Satisfied Customers: 10,524

Experience: 40 years experience, Safe boating instruct., Failure Analysis, Expert Witness

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Hi, welcome to Justanswer. My name is ***** ***** I'd like to help with your question.

Who do I have the pleasure of speaking to?

I normally work 8am-6pm M-F Eastern time but may be on at other times also. Occasionally I can be called away from my computer or working with another customer, I will try and answer back as soon as I can. I'm sorry for any delay you've experienced, I've just come online and saw your question in the queue.

Try this test. Pump the fuel primer ball constantly while the engine acts up. this will take the place of the fuel pump. If it runs better then you need a fuel pump. If not then put it on a temporary tank, if it runs better then your boat has a fuel system issue. If neither of those things work, then you will probably have to have the carbs professionally cleaned using an ultrasonic cleaner, this is often the only way to get ethanol deposits out of the passages.

Ted G., Marine Mechanic

Category: Boat

Satisfied Customers: 10,524

Experience: 40 years experience, Safe boating instruct., Failure Analysis, Expert Witness

Verified

Ted G. and 87 other Boat Specialists are ready to help you

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Customer reply replied 1 year ago

Thanks so much Ted. I’ll try that this weekend . Hopefully that will give me the answer.

Customer reply replied 1 year ago

Hey Ted I just tried pumping the fuel ball while running the engine. It went to a smooth idle with no reving up and down. I’m going to get the fuel pump and change it out. I’ll let you know what happens after that. If it runs well at idle I’ll take it out and see how it is under a load. Thanks bud.

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