1968 3hp Johnson runs for few seconds then cuts out

[davhen2311]

Outboard has sat a while in storage apparently. Couldn't get her fired up so bought new spark plugs gapped them at 0.30 then put some petrol/oil mix in each cylinder and replaced plugs. She fired up after the third pull but lasted around 10 seconds then a loud pop when it cut out. It was also smoking. Repeated with the petrol in each cylinders again and it started up but lasted 2 secs with smoke coming from lower.

Any ideas?
Thanks

 

[Bosunsmate]

Re: 1968 3hp Johnson runs for few seconds then cuts out

clean the carb thoroughly

 

[Bosunsmate]

Re: 1968 3hp Johnson runs for few seconds then cuts out

and fuel lines

 

[davhen2311]

Re: 1968 3hp Johnson runs for few seconds then cuts out

Thanks Bosunsmate. Are the carb easy to take off on these?

 

[Bosunsmate]

Re: 1968 3hp Johnson runs for few seconds then cuts out

not sure never tried one.
unlikely to be hard

 

[davhen2311]

Re: 1968 3hp Johnson runs for few seconds then cuts out

Forgot to mention I am bypassing the fuel pump/filter as one of the gaskets has gone and is spraying fuel out everywhere. Could it be cutting out due to the fact the pump/gasket is not currently hooked up

 

[Bosunsmate]

Re: 1968 3hp Johnson runs for few seconds then cuts out

maybe, not sure

 

[Bosunsmate]

Re: 1968 3hp Johnson runs for few seconds then cuts out

depends if leak is affecting crankcase.
would need to see pix

 

[nwcove]

Re: 1968 3hp Johnson runs for few seconds then cuts out

Forgot to mention I am bypassing the fuel pump/filter as one of the gaskets has gone and is spraying fuel out everywhere. Could it be cutting out due to the fact the pump/gasket is not currently hooked up

is the bottom of the tank sitting higher than the carb? im with bosun tho, carb will need to be properly cleaned and kitted as the motor should idle for a minute or more just from the fuel in the bowl.

 

[davhen2311]

Re: 1968 3hp Johnson runs for few seconds then cuts out

The tank is sitting quite a bit lower, primed fuel till the bulb goes hard. Can see fuel running in fuel line to the carb. Thing is the engine only wants to fire up at all when have put some fuel in the cylinders.

 

[davhen2311]

Re: 1968 3hp Johnson runs for few seconds then cuts out

I will also have to try and source some gasket sheeting to make new gaskets for the fuel pump/filter as a new pump will cost me around ?50

 

[nwcove]

Re: 1968 3hp Johnson runs for few seconds then cuts out

if all were good with the carb, it should run for a minute or two just from the gas in the bowl. no rebuild kits available for the pump on your side of the pond?

 

[davhen2311]

Re: 1968 3hp Johnson runs for few seconds then cuts out

Not sure a rebuild kit is available for the pump at all. Will probably get some gasket sheeting and cut them myself. I think cleaning the carb as you suggested will be on my things to do and hopefully get this baby running

 

[racerone]

Re: 1968 3hp Johnson runs for few seconds then cuts out

A rebuild kit will be available you just need to be persistent in your search.-------That pump was used in one way or another up to at least 98.----Look at different years and hp motors.

 

[davhen2311]

Re: 1968 3hp Johnson runs for few seconds then cuts out

Took the carb apart and cleaned it and used compressed air on any openings. I then managed to get the engine running for 3 seconds again this time with no smoke.
I have raised adjusting the rich/ lean screw but nothing.

Cheers I found a pump rebuild kit on ebay That should be with me in a couple of weeks.

Not sure what else I can do. Compression is at 90psi each cylinder and I'm getting spark on both plugs, plugs gapped at 0.30

 

[Bosunsmate]

Re: 1968 3hp Johnson runs for few seconds then cuts out

ground your plugs ht leads elsewhere on the engine then pull the cord a few times.
A both plugs wet with fuel?

 

[Bosunsmate]

Re: 1968 3hp Johnson runs for few seconds then cuts out

Are you checking spark with a spark tester?

 

[davhen2311]

Re: 1968 3hp Johnson runs for few seconds then cuts out

Yep using spark testers that give off a light

 

[Bosunsmate]

Re: 1968 3hp Johnson runs for few seconds then cuts out

ground your plugs ht leads elsewhere on the engine then pull the cord a few times.
A both plugs wet with fuel?

Have you done this?