3hp Evinrude help needed

[AusOB_Collector]

Hello all

I have a 1964 3hp evinrude lightwin (weedless drive) that I intend to put on the back of my dinghy to use as a tender, but I can't get it to stay running.
I have cleaned and adjusted points, now it has nice blue spark on both cylinders, I have installed a new carburettor kit, replaced the head gasket and surfaced the cylinder head, and now it has good compression.
I can get it to start and run, but not for any more that a minute at the most. It starts in the start position but goes from a slow idle (in the start position) and then increases revs and dies back down. I can keep it running if I play with the mixture screw, but after a while it dies anyway. I can start it up on the first pull after it stopped as well.

Do you have any ideas of what it wrong?

Any help appreciated.

Cheers
BP

[Niander101]

Crankcase leaking in air somehow?
or crank oil seals?
or tank filler cap air hole blocked?

[AusOB_Collector]

Fuel tank cap is fine, vent works well.
I believe that This particular engine doesn't have any oil seals, I could be wrong but looking at parts diagrams they don't show up.
I haven't had the crankcase apart so I see no reason why it would let some air in, but it is a possibility.

Could it maybe be that once the coils heat up when the outboard is running, they stop working until they cool down?

Cheers
BP

[Vic]

Checked fuel filter in tank ? and fuel flow to carb ?

Playing with the choke help at all?

I take it carb overhaul included thorough clean and replacement high speed orifice


Initial setting for the slow running mixture screw is 1½ turns out from gently seated.

Officially the fuel mix for all OMC from 1964 and later engines is 50:1 but these small engines with all plain bearings need 24:1 Like 'gulls they rely on the oil to seal the crankcase in the absence of lip seals.

Coils look OK ?

Tried new plugs? Currently recommended type is Champion J6C gapped at 0.030" but personally would be happy with NGK B6S if Champions not readily available.

[Collector Inspector]

Waited for someone to mention the gallery plugs.....did not happen so;

There should be 4 lead shot plugs as well as the small fuel rail plate .

See pic showing 3 shot. 1/8"

Any of them not sealed...................will be as you described as a problem.

Too much air pressure over 6psi will blow the shot out when cleaning. You will not have noticed if this is the case aye.

This is a 6Hp carb but you get the general idea.

Cheers

B[/color]

[Collector Inspector]

Just had a thort after the conversation just now..............The other cause could be the jam nut packing seals on the mixture screw.

If the needle adjuster can be wiggled then there is obviously air leaking past those seals into the fuel rail.

Tighten the jam nut carefully until the needle is firm to turn and or does not move sideways. Do not over tighten past that.

If the Old Dear runs better I suggest in replacing the packing washers x 2 behind the jam nut. They will be dead if this fixed or did not fix aye.

Yes I can not find my pen so used green blade...........Ship's Cat Cello was last seen nicking off with pen yesterday........I have absolutely no idea why............feline thing I reckon.

I believe that you are sending me some pics of them that you have in a kit to confirm? Maybe post them for others aye.

Might as well give lead shots a gentle tap while you are at it.............

By the way................this post should be moved to Non Seagulls.

Cheers

B[/color]

[AusOB_Collector]

Since recent conversation I have checked the mixture screw, it can be wiggled around quite a lot. I will post pics of the washers when I find them, they are in the same spot until I need them and then of course they have been moved .

Cheers
BP

[AusOB_Collector]

Hi All

Thought I'd just follow up and close this topic -

Last week B kindly lent me a good carb for the 3hp Evinrude andit does run as it should with that carb, so I have come to the conclusion that the high speed jet/ galleries etc were dirty or plugged up on the carbie that I had.

Thanks everyone for your input and help with this!

Cheers
BP