Honda 40HP outboard will not plane our smokercraft

Hello all
I have a Honda 40hp and I have replaced the waterpump/impeller and also rebuilt the carburetors. I have made adjustments so now the motor starts and runs but when trying to get it on plane it occasionally stalls and if not stalling it will rev higher but NOT get the boat to plane even at full throttle.

Im out of ideas and do not have a lot of experience with outboards so Im turning for help to anyone here with ideas.

Thank you in advance for your response
Rich

If it's stalling or trying to stall when trying to get on plane, it's running out of gas. Your job will be to find out why. It could be the pick up tube inside the gas tank, the fuel line connector on either end of the fuel line could be sucking air, a fuel line could be collapsing internally, the fuel filter (located down below the carbs) could be full of water/crud, or you could possibly still have carb issues. I've done at least a hundred of those carbs, so you would think by now I'd be getting pretty good with them, but I STILL end up going back through them on occasion. Point being there, just because you went through them once doesn't mean you got them right.

Is it starting and idling fine? Is this problem only showing up while accelerating (trying to get the boat on plane)?

Not hard to try a different tank and fuel line maybe.

Have you tried squeezing the primer bulb when this is happening? When squeezing the primer bulb, is there any sign of fuel appearing where it shouldn't, indicating a leak?

Alan Hicks said:

If it's stalling or trying to stall when trying to get on plane, it's running out of gas. Your job will be to find out why. It could be the pick up tube inside the gas tank, the fuel line connector on either end of the fuel line could be sucking air, a fuel line could be collapsing internally, the fuel filter (located down below the carbs) could be full of water/crud, or you could possibly still have carb issues. I've done at least a hundred of those carbs, so you would think by now I'd be getting pretty good with them, but I STILL end up going back through them on occasion. Point being there, just because you went through them once doesn't mean you got them right.

Is it starting and idling fine? Is this problem only showing up while accelerating (trying to get the boat on plane)?

Not hard to try a different tank and fuel line maybe.

Have you tried squeezing the primer bulb when this is happening? When squeezing the primer bulb, is there any sign of fuel appearing where it shouldn't, indicating a leak?

Click to expand...

Thank you for the response

its starts ok and idles...but initially tries to die when accelerating (have to accelerate slowly)
Its goes a little faster but can not get on plane

I have not tried squeezing the bulb

I sure was hoping to not take the carbs back off but maybe that is what I will have to do

Hi,
Sorry you're having problems.
I agree completely with what Alan says above and squeezing the primer bulb is a tried and true troubleshooting step.

The Keihan carbs used on Hondas can very difficult to get cleaned out properly. There's much more to it than meets the eye of the uninitiated. They do sell an excellent carb manual that can really help. Let me know if you're interested in buying one and I'll send the publications link.

One thing I can also suggest to check as a "basic step" is to closely examine the fuel line disconnect fitting at the outboard. That fitting is a "pin to check valve" type quick connector. Meaning that a pin on the one side pushes open a valve on the other side of the fitting when you snap them together.

Over time the pin and valve face can wear due to vibration and change dimensionallly so that the valve won't fully open. Also, the fitting can wear in such a way that it gets a bit of "slop" in it and that can cause the pin to not align properly with the valve and, again, the valve won't fully open. Fuel flow will be restricted in either case.

It's a simple thing that you can easily check before you dive back into the carbs or get into fuel pump testing.

Good luck.