HELP - 6x4 Backfiring and No Start

afavia

New member
I purchased a 1998 JD 6x4 with Kawasaki FD620D Liquid Cooled engine that will not start and only backfires through the carb when starting attempt.

I have completed the following:
1. Compression tests show 175/180
2. Flywheel rotated to TDC on each cylinder and valves adjusted to 0.010
2a. I made sure of TDC with a screwdriver in the spark hole.
3. All push rods and rockers checked and confirmed ok.
4. Valves and rockers operate as should with starter motor, cam gear must be ok.
5. Spraying starting fluid in carb or directly in intake only can achieve a backfire through carb / intake
6. Spark / Fire tested and successful at each plug. Verified against block and with spark plug tool.
7. Fuel verified and confirmed at carb. Electric Fuel Pump.

Next Steps I am planning:
1. I ordered new spark plugs (NGK BMR2A)
2. I ordered a new carb
3. I will clean out the spark arrestor and muffler.
4. Planning on pulling the flywheel and checking woodriff key.

I am honestly stumped on this. I have good air, fuel and spark. I have tried with choke, air filter removed, carb covered with hand, spray, etc. Also, the oil is overfull and thin but clean and correctly colored. Possible fuel in gas tank from starting attempt too many times without firing?

Any help would be appreciated.
 

bczoom

Senior Member
Staff member
Gold Site Supporter
Sounds like you're covering all bases.

Another thing is if it's running too lean, that can cause this as well.
Have you checked:
If it has a fuel pump, make sure it's working and not clogged.
Check (or replace) the fuel line from the tank to the carb. If there's even the slightest hole or crack, it'll pull in air and again make the mix too lean.
Check the pipe and gasgets from the carb to the intake manifold. Again, if there's any air being sucked in, it'll be way too lean.
 

afavia

New member
Good morning bczoom:

It is an electric fuel pump and it is free flowing fuel to the carb without restriction. I will check the lines to make sure there is not a small air leak. I will also reseal the gaskets and replace to ensure proper seal
 

bczoom

Senior Member
Staff member
Gold Site Supporter
Good morning bczoom:

I will check the lines to make sure there is not a small air leak. I will also reseal the gaskets and replace to ensure proper seal

Since you're replacing everything already (coupled with the fact it's over 20 years old), I'd replace all the rubber fuel lines anyway. I don't trust my eyesight to find pinholes in fuel lines.
 

afavia

New member
I rented (2) two jaw pullers, however the 1st one (5 ton) was too small, and the 2nd one (7 ton) was too think to fit behind the flywheel and the block. Anyone have a trick to get the flywheel off without using a hammer and pry bar?
 

bczoom

Senior Member
Staff member
Gold Site Supporter
Do you have any Kroil or other good penetrating oil? I'd apply that to where the shaft and wheel meet.

Are you doing this because of this statement? "Planning on pulling the flywheel and checking woodriff key."
Can you see the key once you pulled the nut off the shaft? A visual inspection should tell you if the key is in place and looks good.
 

afavia

New member
I was able to remove the flywheel with a harmonic puller. To my surprise the woodriff key is actually a part of the crank and not seperate? I cleaned everything up and took the opp. to replace the plugs and again re-seal the carb with new gaskets and gasket sealer. It fired up! I have no idea what I did to correct this issue, as nothing else was really improved or changed?
 
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