jd 420 lp

[mwm]

Just purchased a 420lp tractor..lp tank was empty so got local dealer to fill it for me.tractor ran good for a few hours,sounds good. next time i opened the vapor value to start the engine it sounds like the propane is going directly thru the carburetor to the air breather and tractor won't start. don't know much about propane need some help.

 

[Leroy Cochran]

I had to repair the lp converter on my 730lp. That fix it.

 

[mwm]

thanks leroy, youre input will surely help me

 

[wilamayb]

I'll second Leroy's thoughts on the converter being the problem. Sounds like either the diaphragm is busted or one of the valves has issues within the converter.

 

[mwm]

thanks now are parts still on the market to fix it

 

[Jdtractorman123]

I have seen that on more than one of my lp tractors and what I found is if you briefly crack the valve then close it , then start the engine with it closed and slowly crack valve when it starts . What happens is the converter is not reducing the pressure coming out of tank and in turn it puts way too much propane in cylinders causing it to not start. Still you will need to check and or build the regulator. Dearly departed does have some kits but you need to verify your model number,. Hope this helps!

 

[Hugh McKinney]

Yes, if your 420 has the Century regulator/vaporizer, they are. Century got bought by Impco, and you can get complete rebuild kits from Davenport Tractor or from Carb and Turbo Systems, from Shakopee, Minnesota. Under a hundred bucks, either way. Hugh

 

[mwm]

the tractor has 2 values to open up when starting engine, one vapor and one liquid . in what order do you open the values ?

 

[Jdtractorman123]

you crack the vapor slowly . liquid is used after the engine is up to operating temp. some people never run but on vapor.

 

[mwm]

thank you for you help . any other information on this subject is appreciated

 

[AlanA]

ALWAYS, turn the gas off and let the motor die, THEN turn off the ignition. If you turn the key off first, you still have HOT water in the vaporizer/regulator with the liquid fuel. This will build up high pressure, and badly abuse the gaskets in the vaporizer.

By the book, you start it on vapor, then open the liquid line when it warms up, and turn off the vapor line. For parades, or putting around in the yard, you will have plenty of vapor pressure to run the tractor. If you WORK it, pressure will drop too low unless you let the hot water circulating thru the vaporizer boil the liquid.

Alan