Honda BF40 startup problems

[wtaylord]

Hi All! Here I am after a year and a half after purchasing my beautiful new <to me>C-Dory which I have spent a lot of time on updating equipment, etc, and thought I was ready to splash her. Wrong! Engines will not run properly. They both behave exactly the same. Will start with a lot of throttle but are shaking - misfiring . Also one overheated. On initial startup ,water coming from indicator hole in solid stream , next startup barely dripping. Took apart water pump and thermostat housing - impellor looked fine - thermo opened at spec temps passages quite clean. Gas 3 months old with additive. Hooked portable tank with brand new gas to engine - made no difference. Spark plugs gapped and like new. I'm at my wits end. I'ts like there is some special controller keeping the engine from coming up to speed! Please helpl Warren

[starcrafttom]

Are you running the motors on a flush or in the water? Your motors have a Rev limiter when over heated or in the up postions.

From the manual :Overrev Limiter

[PaulNBriannaLynn]

The carburated BF40s are known to have notoriously small jets compared to other outboards. I absolutely love mine, but expect to have to rebuild the carbs at some point down the road. Some of the symptons sound like clogged jets to me.

Also outboards can act differently when in a driveway on earmuffs, when compared in a tank or with the boat launched. The motors arent getting the water causing them to run hot and there's a pressure difference. A low compression outboard will start and run in the driveway, but will not start once you're launched as an example. That was a head scratcher for me

[digger]

Sounds like the main metering jet. They have a very small hole that passes through the jet tube, and once plugged, they are almost impossible to clean. New ones are about $15 each, so for about $45 in parts for each motor, it should be fine. The carbs need to come off, and the float bowl removed (4screws). Then there is a cover screw in the center of each bowl area theat comes out. Once that is done, the jets slide out. Ron

[Fairbro]

Don't worry about the "tell tale" stream too much if the alarms are not sounding. My 40's have been doing that for 11 years now. I keep weed whip line handy to rod out the pee holes and that restores the stream and my peace of mind. I have had the rev limiters activate and it is scary but then you realize the tilt is wrong or you are loaded differently and then it all make sense. Sometimes the boat is smarter than me. Hope that's your situation.

[potter water]

long shot, but are you properly propped for your altitude? Too much bite on the prop will cause engines to do strange things...not just bog down. Of course, you can't tell anything about the prop issue unless you are in the water and moving along.

Also, if you are using muffs, you aren't getting the same cooling that you would if you put a trash can full of water up under the engine. Muffs are usually only good for idle to rinse the waterways from any salt water exposure. Trying to run an engine up with the muffs is a mistake. I always do my drive way engine tests with the garbage can full of water method. And never rev the engines over about 1500 rpm, and then only for a short time. That kind of test should answer questions about the pee stream. Muffs may not get you anything other than an intermittent pee stream.

Good luck. Let us know what you find out.

I'd probably put it in the water and give it a real test.

[bcassal]

It sounds like carbs to me. I have twin 40's. I bought them with about 400- hrs and they had been sitting a lot. They ran like crap. I had the carbs rebuilt and have kept ethanol out of the gas and they're are running wonderfully for about 300+ hours now.
Those carbs are finicky little things and there are 6 of them. Expensive to fix. I hired them out for $1500. Get them set up right, keep your gas clean, and they will serve you well.

Carpy

[T.R. Bauer]

I would go with carbs......You know a little seafoam does wonders sometimes too. I'd at least try it.

[Chester]

I've used Techron additive with success to rejuvenate sickly carbs. Get the Techron additive, not the diluted additive with Techron.
Good luck and keep us posted.

[Chester]

Update?