Colorado Mechanic?

[robotmark]

Hi folks – I’ve been working on this 1971 Johnson 40hp for some time now and still can’t get it running. I think it’s due for a professional set of eyes. Does anyone know of any outboard mechanics in Colorado? I’m in the Boulder area but happy to travel. I’ve called around to a few of the marinas but no one’s calling me back. Thanks so much!

[Fred Hickman]

What have you done to this motor? Be specific, please.

[robotmark]

Hi Fred,

The motor was operational last year. One day on the water, when I started it up, it flooded immediately. If I disconnected the fuel line the flooding would stop, the engine would start and it would continue to run until it used up the fuel left in the carb. I explained the situation to the forum and there was advice to clean out the carb and to check out the fuel pump. I did both. I completely disassembled the carb, put in a new rebuild kit with fresh gaskets and float. I also installed a brand new fuel pump. When I got it all back together and attempted to start, it did exactly the same thing as before – it immediately floods. But now I can’t even get it to run if I disconnect the fuel line. It won’t turn over at all.

So, I’m not sure what I’m overlooking, or what my next steps should be, which is why I’m looking for a professional or someone else who knows these motors better than I do so we can figure out what’s wrong.

Thanks!

-Mark

[Mumbles]

Sounds like the float valve in the carb is leaking and was it replaced to and its brass seat tightened securely? Sometimes the float will hang-up on the bowl gasket to, which requires trimming the gasket a bit. If the motor won’t crank over now, either the battery is dead or one of the cylinders may be full of gas and it’s hydro locking. Best to pull the plugs, ground the leads and try cranking it over to dry out the cylinders.

Also, make sure the bowl vent isn’t plugged. Small insects like to get in there and build a nest.

• This reply was modified 4 years, 6 months ago by Mumbles.

[robotmark]

can you be more specific about A. grounding the leads, and B. which of the vents if the bowl vent. I’m happy to do the work but I want to make sure I do it 🙂

Thanks!

[Mumbles]

A. Ground the spark plug leads while they are undone. The terminals inside must be connected to the block or another ground to prevent sparks or damage to the coils. The high voltage generated needs somewhere to go and if the leads aren’t grounded, it can short out inside the coils. Two wires with alligator clips on each end will work.

B. Without your particular carburetor in hand to look at, the vent is usually a small hole on the side of the body or sometimes facing the front. With the bowl and float removed, you might be able to see it in the body above the float or it may have a cover over it. Either way, it must be open and can be blown out with compressed air.

Was the thin gasket included in the kit installed under the brass float valve?

[Author]

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