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More JD 720 LPG problems any ideas????? (long post

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Jeff

11-01-2003 22:41:02




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I posted here a week or so ago about our 720 that won't start. We drove it home one day from a show and it hasn't run since. At first we figured it was the convertor and was looking for a rebuild kit, no luck. Then we went ahead and ordered a new one, got it hooked up and still nothing. The fuel tank is low at about 12% but it has run with it being lower before.

Friend of my dad's who used to work on LPG stuff said to make sure that the carb has suction to the convertor as it has to have some to make the valve or something work. Didn't have that or not much and dad put a kit in the carb, still nothing.

Got a carb off of a 70 LPG that was running and tryied it as well with the same results, nothing. We have checked the timing and it seems to be doing fine. For some reason it doesn't seem to be getting fuel to the engine or maybe even not to the carb.

WE know for sure we have fuel going to the convertor as you can turn the liquid on and see it coming out at the connection to he convertor. When we hit the button on the convertor to squirt fuel into the carb it doesn't make a sound or if it does it ia real faint. Seems I heard one once that when they hit the button it sounded like an aersol can being used. Dad says this is normal and I think not.

Seems to be in time and like I said earlier it has a real good spark. any ideas and thoughts are greatly appreciated as my dad is about frustrated with the whole thing.

Thanks!!!!!

Any ideas on what to look for!

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Justin

04-08-2004 18:05:30




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 Re: More JD 720 LPG problems any ideas????? (long in reply to Jeff, 11-01-2003 22:41:02  
I had the same problem with my 720 LP. Come to find out that the oil pan didnt have any oil in it. We filled it up and it has fun every since. Hope this helps.



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DRL

11-02-2003 15:09:50




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 Re: More JD 720 LPG problems any ideas????? (long in reply to Jeff, 11-01-2003 22:41:02  
Don't know if this will help, but here goes. On dad's 620LP, moisture will build up in the cylinders from setting or not running it until it gets good and hot. May have good spark, but too much moisture to fire. He generally will take the spark plugs out and replace them with a spare pair, or take compressed air and blow the moisture off the plugs. This advise was given to him from an old timer JD mechanic who knew these two bangers pretty well. Has worked every time so far. Worth a try. Also, on dad's 620, there is a fuel switch that kind of looks like a gasoline sediment bowl that is electrically opened when you turn on the ignition switch. This valve should click when the ignition switch it turned on. This has given us problems in the past. We could usually take something non metallic, like a hammer handle, and tap the fuel valve on the side a couple of times, and it would go ahead and open up.

Can be frustrating at times. When these LP tractors run, they really run, and when they don't, they really don't! Hope you get it running soon.

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Kent of SW MO

11-02-2003 13:37:43




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 Re: More JD 720 LPG problems any ideas????? (long in reply to Jeff, 11-01-2003 22:41:02  
Does your 720 have an fuel lock valve on it. the coil may be bad or you have lost the power to it.



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mike in new mexico

11-02-2003 09:52:09




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 Re: More JD 720 LPG problems any ideas????? (long in reply to Jeff, 11-01-2003 22:41:02  
On my 730 lp,the choke rod is really a" Dechoker" if you flood the engine then you pull the choke rod out and it stops all the propane from getting to the carb,then you turn the engine over a few times to clear the propane from the engine and then you push the choke rod in all the way and try to start the motor again. if I was you I would look at the choke and see if it was letting the gas in . -mike

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twopop

11-02-2003 08:27:10




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 Re: More JD 720 LPG problems any ideas????? (long in reply to Jeff, 11-01-2003 22:41:02  
if its an impco regulator,it lets some fuel thru as long as the switch in on.if when you push the button,nothing happens,then the manifold could be flooded with fuel.I suggest you purge the engine of fuel,start cranking engine with fuel turned off,then open fuel valve.



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Fudd

11-02-2003 07:51:02




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 Re: More JD 720 LPG problems any ideas????? (long in reply to Jeff, 11-01-2003 22:41:02  
You are right when you say you should hear something when you push on the button on the converter. When you try to start it, do you open the throttle? You need lots of vacuum when you are starting on propane and a wide open throttle plate helps this. On our trucks there is a valve operated by a diaphram that lets the vapor into the carb. If there is one on your system, maybe it's stuck or has a hole in it. Good luck.

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