1st boat, last boat?

[dbak5451]

I bought a 59' Dorsett runaboat last year, cheap, but had bad transom, stringers etc..Rebuilt the transom, stringers, floor, steering, new seats, paint, whatever...beautiful boat now. It had a '60 40hp Evinrude that ran but wouldn't idle, ran rich. I rebuilt the carb, new points, plugs, condensers. Same thing. Took it to the marine shop down the road, they replaced a seal, told me it was great, compression within range. Maiden voyage, wouldn't get above 5 mph. Dinked with it over the course of several months, same thing every time I put it in the water. Gave up, bought a '65 100 hp Merc. Same thing!! Starts right up, idles great, gets up to 5 to 10 mph and just sits there.
Looks good in my garage but geez..I'm kinda commited to the thing now. What to do??

 

[Plainsman]

Re: 1st boat, last boat?

Welcome to iboats!

First I'd get a compression test, then check spark. Pull the carbs and disassemble, soak in carb cleaner, blow them out with air and install new carb kit.
I'd also do a decarb on it (there is a "How to" in the FAQ section)

 

[merc1]

Re: 1st boat, last boat?

You might check the shift cable's and make sure something is not slipping. Good Luck.

 

[Plainsman]

Re: 1st boat, last boat?

Another thought is a spun prop. Are your RPM's staying up and you have no speed? You can make a mark in the prop and housing. Take it for a ride and then see if the marks still line up.

 

[Nova II 260]

Re: 1st boat, last boat?

I'm NOT a O/B man, but if both engines react the same, I'd look for the components that are common to both: Fuel supply( tank, hose, vent) electrical, manual controls (adjustment), ????

 

[dbak5451]

Re: 1st boat, last boat?

Thanks Nova, but the first thought was to replace all 'common items' between both engines, so replaced cables, fuel lines & connectors etc...I find it hard to believe both engines have a similar problem, but guess I have to go by the premise that both are faulty.

 

[dbak5451]

Re: 1st boat, last boat?

Hi Plainsman, No the RPMs will not go up, just flatten out at 1/3 throttle or so.
I have reservations about the throttle connection..seems very limited, opens or closes the butterfly valves and thats it, is that the whole range? It does have rpms in a barrel, just not on the water. thanks

 

[Plainsman]

Re: 1st boat, last boat?

I'd still clean and rebuild the carbs. Does pumping the fuel bulb help on the water? If so then the fuel pump needs a new kit as well.

Maybe Laddies has some other thoughts.

 

[MikDee]

Re: 1st boat, last boat?

It sounds like your spark advance plate under the flywheel is not moving or not moving enough, take a look when you open the throttle.

 

[glen357]

Re: 1st boat, last boat?

Could this boat be waterloged, Has it ever run right? When you take it out of the water is it heavy? Just a though that would be common to both motors. G

 

[stnb4ever]

Re: 1st boat, last boat?

Just a thought, how is you fuel? Old fuel has a tendency to break down after as little as four months. If it were bad fuel it would definately have the same effect on both engines.

 

[Windykid]

Re: 1st boat, last boat?

Is the tank vent open?????

Can you throttle up manualy with same results??

Butterfly open all the way??

 

[hkeiner]

Re: 1st boat, last boat?

The first thing I would do is run the motor on a portable 3 gallon fuel tank containing new fuel. If the problem goes away, you have narrowed down the problem to fuel supply (bad gas, leaking fuel line, clogged fuel line, etc.). If the problem does not go away, you have at least eliminated these possibilities and you can turn your focus on to the many other possibilities.​

The next thing I would do is confirm that pressure in the fuel line between the fuel pump and the carbs is not less than spec. A pressure gauge is not an expensive tool and a good way to isolate fuel delivery problems. The specs should be in your shop manual. If the pressure is below the spec, then you probably have a bad fuel pump. If the pressure is above spec, then you can focus on other possibilities (e.g. the carbs, link and sync settings, failed ignition system components, etc. )​

That is what I would initially do anyway. Others may have additional or better suggestions.​

 

[dbak5451]

Re: 1st boat, last boat?

Thanks all. I have used fresh fuel, the boat's been rebuilt so it's not waterlogged, I haven't tried manually opening the throttle while on the water,(I'll have the wife do it), I will pick up a pressure gauge and look at that, I'm waiting for the repair manual for specs, and thanks Plainsman I'll give the bulb a sqeeze. And I'll look at the spark advance plate, thanks Mikdee. Ok, back to the garage, and hopefully back to the water. Again thanks for the insights.
I'll let ya know.

 

[shipoffools]

Re: 1st boat, last boat?

Cosidering both are older engines I would certainly rebuild the fuel pump, while determining fuel pressure is not a bad idea, a fuel pump rebuild is fairly cheap and easy and may just solve the problem.

 

[wysocki389]

Re: 1st boat, last boat?

don't know specifics about your particular engine(s) but have you checked for exhaust restrictions if applicable?

Not quite the same league but I had 12 hp lawn tractor motor that behaved in a similar fashion ... seems some critters had decided to call the exhaust pipe home sweet home.

Critter stuff = back pressure = no-go

just my 2 cents worth