1978 liquifire wont run when hot

[liquifireZach]

I have a 1978 John Deere 440 liquifire. The problem is that after i ride it for 20 min it starts to bogg and then the engine turns off. It has a full tank of fuel, also has brand new spark plugs, its getting spark. Does anyone know what the problem could be? I have been told water pump might be bad ,but i dont know how to test that?

I also need some parts for it. I need back grab bar, speedometer, temp gauge, and hood vent.
If anyone could help me find these i will greatly appreciate that

Thanks Zach

[SpitfireKing]

does it have really good spark, or just spark? Sounds like something in the ignition system is getting warm and cutting out...that or some strange vapour lock? Have you moved any fuel lines around or have something too close to the heat?

[liquifireZach]

I just took the plugs out and put them back in the boots and i seen that they had spark on the cylinder heads, i am not quite sure if it was good i just seen spark so i dont know. All the fuel lines are right were there supposed to be I think, there is a fuel line that comes from the tank and goes to the fuel pump at the buttom and them the fuel lines come to the carbs right above the fuel pump.

[harleysportster]

How old are the fuel filters? Are they clear and full or only partial full.?

[liquifireZach]

My fuel filters are brand new at the end of the season last year when i parked it, and i have fresh gas also. When the sled is running and starts to bogg i put the choke on and it still continues to die.

[harleysportster]

To test for fuel delivery:
turn off key, un-hook the fuel line at each carb, (you can do this 1 at time) place the line in a jar and pull over the engine and watch for fuel pumping out. It should pulse out as the engine is pulled over.
Before going any farther, comfirm the fuel delivery.

[liquifireZach]

I pulled them both off and checked that and it is getting fuel in pulses so what else could be the problem?

[harleysportster]

Look at the plugs to see if they are dry which would indicate clogged carbs or stuck floats

[liquifireZach]

The plugs are brend new and the right cylinder is dry and the left cylinder is dryer. The sled starts right up in the cold but just not when it is hot.

[harleysportster]

What's the history of the engine? Has itr been rebuilt or new seals installed in the last few years?

[harleysportster]

Two things come to mind, bad crank seals or weak ignition. Both could fail when warmed up. Do you still have the original Prestolite CDI box on the engine?

[liquifireZach]

The only thing i have done engine wise to the sled is clean carbs and fuel pump and also put fresh coolant in it every year. The sled has not been rebuilt as far as i know. I got it in 2008 and i finally got it running good last year at the end of the season and it was running good all this past week and now it is doing this. It has two coils above the carbs and has the cdi box below the carbs and to the right, they look all original.

[harleysportster]

did you replace the filter in the tank?

[liquifireZach]

Yes, I also put new fuel lines on, and a fuel filter between the fuel pump and fuel tank

[harleysportster]

Did you ever check or replace the cooling belt on the watr pump?
When you are able to start it back up, try spraying carb cleaner on the crank seal behind the primary clutch. If the engine revs up, there is a bad seal.
If you are handy with an ohm meter, check the ohm readings on the stator when it quits running.
http://www.hewtechelectronics.com/image ... WIRING.pdf