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2003 Honda 9.9 runs good but bogs down once warm.

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Andy CT

New member
I picked up a used 2003 Honda 9.9 to go fishing with my kids. The motor starts and runs good but once it warms up (5-10 min) it will not run at full throttle and bogs down as if it is running out of fuel. I have changed the fuel filter, fuel, plugs, oil. It will run fine up to about 1/2 throttle, but after that it lays down and doesn't give much power. I am thinking fuel pump or carburetor problem? I'm new to boating, so any help would be greatly appreciated!
 
This doesn't sound like carburettor to me, particularly if it running well when cold. It could be fuel pump or fuel tank breather. Does the bulb stay primed and solid? As the engine heats there are a number of non fuel related things that can do wrong. It could be heat affecting the coils under the flywheel giving you a bad spark, if could be something expanding and seizing making it harder for the engine to turn or expansion causing a loss of compression. I'd start my tightening all the head and intake manifold bolts and doing a compression test.

Stuart
 
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I have even changed to a different fuel tank with a different hose so that is not it. I will check the bolts but it still runs good but just seems to run out of fuel in the higher RPM's when warm. It is still running but just bogs down. I think I will just order a new pump. Are they hard to replace and were is a good place to get one?
Thanks
 
Could it be overheating? Have you changed the impeller since you bought it? Thermostat? Doing those, an engine oil change and gear lube service are all the items I would recommend doing to ANY outboard that is purchased used.

Even if it has a good tell tale (pee) stream...it could still be overheating.
 
I am still hoping you did the basic checks/services IE: water pump impeller...thermostat....engine oil and filter along with last, but not least, gear oil change and prop thrust bearing check/cleaning.

But if the problem persists after all of that, the link below is for an outboard similar to yours doing similar antics. It is a long one that goes to a second page but, in the end, has a happy outcome.

Good luck.

http://www.marineengine.com/boat-fo...94-Honda-bf9-9a-15a-crankcase-breather-issues
 
The old owner just had the water pump impeller replaced. I will get a t-sat for it and do a gear oil change, and check the thrust bearing. I just got the full shop manual for it yesterday so I will take a look and dig it to it.

Thanks for all your help. :eek:
 
Andy CT said:
The old owner just had the water pump impeller replaced. I will get a t-sat for it and do a gear oil change, and check the thrust bearing. I just got the full shop manual for it yesterday so I will take a look and dig it to it.

Thanks for all your help. :eek:
Click to expand...
So what was the answer to your problem?
 
The new fuel pump fixed it. When I pulled the old pump and compared it to the new one the old one had less spring to the plunger.
Thanks for the help guys.
 
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