1964 lightwin carb issues

[scorpio65]

I have a 1964 Evinrude Lightwin 3hp. All magneto parts are new and it fires right up if squirted in carb. But will not even attempt to fire without squirt. I have clean fuel, new lines. Float bowl is full....yet nothing. I have had the carb apart and cleaned approx. 10x. Every port, hole, passage is cleaner than new yet no firing. Does anyone have any ideas? I have 9 other small outboards I have resurrected yet this one has me frustrated.

 

[oldboat1]

Filter and/or valve may be blocking fuel flow from tank.

 

[boobie]

How do you know float bowl is full ?

 

[F_R]

Cleaned it 10X, eh? Can we believe you cleaned the orifice plug in the very bottom of the carb?

 

[scorpio65]

Cleaned it 10X, eh? Can we believe you cleaned the orifice plug in the very bottom of the carb?

Yes.

 

[scorpio65]

How do you know float bowl is full ?

Turned out bowl plug and bowl full of fuel drained out.( after petcock was closed.)

 

[scorpio65]

Cleaned it 10X, eh? Can we believe you cleaned the orifice plug in the very bottom of the carb?

Took carb apart 3x this afternoon alone.I removed every plug, screw ,both jets, float, needle valve. Sprayed and blew out every orifice clean.

 

[racerone]

Most carburetor " problems " turn out to be something else.

 

[scorpio65]

Most carburetor " problems " turn out to be something else.

Not sure what? I will start/run as long as I am spraying fuel into carb throat.

 

[oldboat1]

Not your first rodeo, but is the gasket in place under nozzle? Nozzle openings clear? New domed cover on top not fully sealed? Orifice for slow speed needle providing poor fit — buggered up? Needle set at around 1 1/2 open for initial setting? Choke flapper not tightly sealing for cold starting? All lead shots in place?

 

[Willyclay]

While you are contemplating all the previous advice and your next steps, let me share my experience with a 1959 Johnson 35 carburetor that took me down the same path as you seem to be describing. After three cleanings, I finally was able to identify some very hard "crud" in the Low-Speed needle valve passage that had somehow survived the soakings, spray-cleanings and nylon brush attacks. Some scraping with a gunsmith's non-metallic pick finally cleared the passage and it instantly became the great running motor for many years. FYI, my understanding is these old beauties use the Low-Speed fuel metering ONLY for the majority of throttle advance before the High-Speed fuel metering is a factor. Good luck!

 

[Crosbyman]

can you feel the air being sucked in the carb with your hand when a buddy pulls the starter cord.

on the up strokes of the pistons the air should be pulled in ...with gas vapors from that "super clean" fuel bowl

anything (air leaks) lowering that negative pressure will hamper fuel vapors from being sucked in the crankcase.

squirting gas just replaces the vacum pull

btw …. float is not upside down is it ? any cracks in the carb body ??

 

[Crosbyman]

check list ...no glass bowl on yours but same basic issues

 

[Canoe2]

Had a similar problem with that model and figured I had blown everything free and clear. It was suggested to me that I might run a fine wire down the passage leading from the side of the carb bowl into the bottom where the high speed jet seats. I had blown it out with carb cleaner a dozen times and figured that couldn’t be the problem, but it did the trick. Ran like a champ after that.

 

[scorpio65]

Thanx for all the suggestions. I took apart and cleaned everything again. Payed particular attention to slow and main jet orifices with small wire. Got it to fire and start up finally on its own. It runs good from slow idle to half throttle.I can't seem to get it to run over 60%....keeps stalling out. I guess another cleaning of the main orifice and emulsion tube are in order.

 

[Willyclay]

Great news! Hang in there, I know you can whip it.

 

[Crosbyman]

make certain the fat gasket is in place at the bottom of the bowl

make certain 2 small vent holes are not crudded on the tank cap. unscrewing the vent serves no use if the 2 small vents are plugged up look closely to find them

meantime try running with the tank cap off if ok then the vents are crudded up

 

[racerone]

All new ignition.-----But what about condition of pistons / rings ?-----Carburetor is a simple device that responds to air being pulled through it.-----Make sure crankcase suction is good.-----Remove exhaust cover to look at the pistons.----Will cost you a gasket or time to make one !

 

[lindy46]

Thanx for all the suggestions. I took apart and cleaned everything again. Payed particular attention to slow and main jet orifices with small wire. Got it to fire and start up finally on its own. It runs good from slow idle to half throttle.I can't seem to get it to run over 60%....keeps stalling out. I guess another cleaning of the main orifice and emulsion tube are in order.

Check fuel filter - fuel may not be flowing fast enough to keep it running at high speed. If it's the original filter, it needs to be replaced. They can't be cleaned. I've tried!

 

[Crosbyman]

fuel filter is inside the tank above the side valve unscrew the valve body to access it

you can try to back wash it with carb cleaner and high air pressure or remove it and add a small filter along the fuel line to the carb inlet