I went through the carburetor on a 6.5 H.P motor on a log splitter put in a new plug and it started right up but when I put it under a load it died now its backfiring and wont start

Fuel starved, carb should have an idle adjustment which sounds like it is fine. Look for the second adjustment

Richard, First thing to try is to run with out gas cap to see if the caps vent is plugged. It does sound like probable carburetor issue.
• Float Adjustment
• Debris in Carburetor
• Jet, Main Fuel
• Mixture Screws
• Fuel Quality
• Air Cleaner, Restricted
• Fuel Filter, Restricted
• Kinked Fuel Line
• Pump/Fuel Delivery Volume, Low
bad plug wire shorting, weak coil,valve adjustment needed,etc.
Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
http://www4.briggsandstratton.com/miscpdfs/RNT/Carburetion_Troubleshooting_Detail_Reference_Guide.pdf
20HP engine that stalls under load
Engine Dies Under Load

The needle valve and float are stuck inside carburetor. You will have to remove the fuel bowl under carburetor and see if there is something keeping the needle valve from seating. GOOD LUCK FRIEND.

Make sure the device is unplugged from the 240 VAC power source.
Connect the 240 VAC line and neutral wires to the momentary switch. Examine the motor wires to determine line and neutral.
This log splitter is equipped with a control system that requires to be operated by both hands of the user - Left hand controls the
hydraulic control lever while right hand controls the pushbutton
switch. The log splitter will freeze upon absence of either hand. Only
after both hands release the controls, the log pusher starts to return
backward to the starting position.
http://www.masport.co.nz/common/download/556964/
Hope this helped.

It now has a bad dead short in the wiring and that is why the fuse keeps blowing.. Check for bad wiring

Replace the Hydraulic oil in the log splitter after
every 150 hours of use. Take following steps to
replace it.

1. Make sure all moving parts stops and the log splitter is unplugged.
2. Unscrew Oil Drain Bolt with Dipstick to remove it.
3. Turn the log splitter on the Support Leg side over an 4 liters capacity container to drain the hydraulic oil off.
4. Turn the log splitter on the the motor side.
5. Refill fresh hydraulic oil at the volume as per the hydraulic oil capacity of a particular model indicated in above specifications table.
6. Clean the surface of Dipstick on the Oil Drain Bolt and put it back into the oil tank while keep the log splitter vertically.
7. Make sure the level of the refilled oil is just between 2 grooves around the Dipstick.
8. Clean the Oil Drain Bolt before thread them back. Make sure they are tightened to avoid leakage before place the log splitter horizontally.

Periodically check oil level to ensure it is between
2 grooves around the Dipstick. Upon Lower oil
level, oil refilling is required.

Source:
http://www.qci.net/files/5_Ton_Log_Splitter_-_USE_THIS_MANUAL.pdf

Here is the long answer with everything we learned while using a power washer twice a week for years::

It sounds like could be one of the problems listed below or a combination of those things.
1) The exhaust is partially blocked. Check the screen covering exhaust port for carbon and dirt build-up. High-speed exhaust air must pass freely. We finally broke the exhaust screen out with a screwdriver to get our machine going one day.
2) Gas is not flowing freely to carburetor > under gas tank, find the rubber hose connected to carburetor. Pull off rubber hose and make sure gas flows freely. You can use this hose to drain gas tank of old gas ... and then put in fresh gas.
3) Carburetor is partially gummed up and engine cuts off when gas flow slows down. Buy some gum out, and then don't store power washer with gasoline in the tank. Or put additive in gas when storing machine.
4) The choke is letting in too much gas or not enough gas. Try different adjustments. The choke-lever on our power washer got so bad that we could not set throttle at full open or the machine would die. We still use the machine at 2/3 throttle, and then start it each time using WD-40 as described below.
5) Dirty air filter that won't let engine breath enough air to keep up with combustion. Take off air filter and see if problem persists.
6) The spark coil is going bad?? Change spark plug to see if problem persists. Is spark plug wire pushed all the way onto the spark plug?

Now the nitty gritty: we're gonna start that thing right now
7) Take off air filter. Spray WD-40 directly into carburetor. Yes, we use WD-40 every time to start my power washer, and we use the washer twice a week.
Spray in the WD-40, Pull the engine cord. The engine will fire on WD-40. Guaranteed.
Once it starts, keep spraying WD-40 directly into carburetor to keep engine going.
If engine will not fire and keep going on WD-40, then your spark is suspect.
If your engine fires and runs on WD-40 but dies without it, then your gas supply or carburetor are suspect
8) Carburetor problem >>> try Gum out >>> and then take machine to small engine repair shop
9) Spark ... take out spark plug. Put spark wire back on. Hold spark plug by spark wire. Touch metal threads of spark plug to metal opening where plug came out. Metal to metal. Pull back start cord and look for spark between the metal.
If you have no spark, then spark coil is bad >>> take machine to small engine repair shop

Add a comment if you need more help

Two things that can cause this problem. 1. Your carburetor is not set properly and is not letting the engine get enough fuel under a load. 2. Your chain is binding when you put the chain bar down on the log. Make sure your front chain sproket is turning free and is not too sloppy.

First of all, I hate to, but have to ask, have you verified oil level is up to proper level? Have you checked power at directional solenoid when handle is moved to different directions, as well as released? Obviously when handle is in stop position, there shouldn't be power to motor in either direction. I can't see exact model, or design obviously,but that would be a good place to start.

Take a paperclip and clean out the small hole on your gas cap. And yes I am being serious.