BF40 stalls or no power

[CraigsBF40A]

I have a 2004 Honda BF40A. @ years ago I had to hav e the carbs rebuilt and was told to buy premium gas and use Stabil over the winter.
I suspect I did not get a quality job because the motor was hard to start when cold when I got it back and the bowl drains were not connected.

Last fall the water pump failed and triggered the safety circuit and after I alllowed a short time to cool down I restarted it and safety circuit limited the motor to low speed allowing me to return to the dock.

I replaced the worn impeller and the pump worked well, but I only tested the motor while on the trailer, because it was getting to cold ery late in the fall and I winterized the boat. Premium gas with stabil run long enough to get into the carbs.

I started the motor today for the first time this year. It started great and idled smoothly, so I took her out and she ran in reverse and forward at low speed, about trolling speed. When I try go to top speed it will stall if I go too fast and if I raise it slowlty I can only get about 1/3 the speed at full throttle. She still starts and idles great, but at the dock in neutral, if I remove the linkage and try to accelerate fast it hesitates and sometimes back fires when the throttle is released and runs a liittle rough at the highest idle position on the throttle.

I installed 3 new plugs and have good flow through the fuel filter, but haven't tested the fuel pump because the Honda manual from IBoats says It more likely the Thermo switch, or most likely a thermo sensor in a 2004.

I have read the test procedure, but I would like to know if this is a common failure.

Anything else this might be?

 

[CraigsBF40A]

Tested fuel flow through fuel pump by pumping primer ball with the lint the carbs off; lots of gas good floww when pumping the ball.

This morning the motor didn't seem to fire until I pumped the primer untill it got hard, then it popped right off and idled nicely, but would stall if I tried to go from low to fast idle too fast.

I idled the motor until it seemed to be warmed up, but the temp is only about 60 and the lake is not very warm either, and I could go from slow to fast idle without stalling, but occasionally a hesitation when tried to many times in a row.

I shut the motor off and measured the thermal sensor's resistance to be 4.42 kohms; 1 to 5k is normal to 105 degrees.
1.The manual says it should red between 200 and 400 ohms at the motor's normal operating tempature of 105 to 140 degrees.

2. If I disconnect the sensor and start the motor, the symptoms are worse; it starts harder and runs even worse than when it is connected.

Just be sure, I added a fuel system cleaner to the gas and took the boat out and ran it on the lake to circulate the cleaner through the system and plan to let it sit all day

Anyone have any knowledge about this problen?
Any advice?

Craig

 

[jjohnson120]

There are 2 sets of needles, one for low speed and one for fast speeds. Mine did the opposite of what yours is doing. You could get it started then throttle up and it would go, but between the idle speed and WOT, it kept wanting to die. I took it and had the needles replaced and they said that it was due to bad gas like you mentioned in the first post. They said once they get clogged the only way to undo it is replace because they are so small. No amount of carb cleaner or additive will ever blow it out.

What I do is drain the gas, disconnect the fuel line, and start it up. Yes the damn thing will still start with what seems to be no gas. I idle it up as much as possible and let it run till it dies. Then start it and do it probably 5 or 6 more times. They are so fuel efficient it seems like it takes forever, but doing this has kept me from having to have the needles replaced.