Wheel Horse 520H fuel delivery issue

[SLW4220 3]

I have a 1993 520H that was running fine during the last snow fall and plowing in early December 2014.  So with snow predicted in the next few days I started it this morning only to find that the engine would not run smoothly unless choked significantly and with the throttle set high.  And, it won't stay running with out choking and setting the throttle high.   (no trouble starting)

 

It seemed to lope (fast-slow-fast-slow) as if the fuel was being constricted, unless almost fully choked and the throttle set high.   I changed the fuel filter without no improvement.  I also let it run for about 20 minutes to see if that would help clean out a possible restriction, but with no improvement.  This problem occurred since my last successful plowing in December, so it seems to me it must be a fuel delivery issue.

 

I have used regular gas with ethanol and a fuel stabilizer in previous 10 winters and never had any starting or running problems.

 

Thanks in advance for any suggestions that may resolve this problem.

 

Stephen

[wheelhorseman 3,197]

I had a 520H that did what you're experiencing. Mine was a dirty carborator. You probably got a small piece of dirt sucked up into the jets causing it to starve for fuel,just take it apart and clean it thoroughly and put everything back together and it should run like a Swiss watch again, hopefully this helps

[JackC 616]

I have a C-81 with the 8hp Kohler engine that ran perfectly this summer.  It would not start in December.  Turned out the float needle was stuck and fuel could not get into the carburetor.  I had to remove the carburetor from the block in order to drop the bowl to loosen up the float needle.  There were also about a 1/4 teaspoon of ethanol particles in the bowl that i dumped out.  A little moisture absorbed by the ethanol along with cold weather apparently did it. Once I got the float needle loosened up it ran fine without further cleaning or overhauling the carburetor. 

 

Your symptoms are very typical for a dirty 520 carburetor.  It is amazing that you have gone 10 years without a problem.  Some get away with just taking the top off the carburetor and clean what you can get to without removing the carburetor.  The JD manual says you can use crows foot wrenches to remove the carburetor without removing the intake and exhaust manifolds.  My 520 HC ran perfectly and then all of a sudden developed the symptoms you described.  I removed and cleaned the carburetor and then it ran fine afterwards.  I can buy ethanol free fuel in NY state and that is all I use now.

 

I also keep spare carburetors ready to go so I can swap and go and clean later.

Edited January 5, 2015 by JackC

[N3PUY 1,031]

Try just taking the top off the carb.   Spray every little hole with carb cleaner.   Reassemble.   Worked for me.

[cheesegrader 433]

I hate this problem.  All three of my 520's have done this at one time or another.

I agree that this sounds like a fuel delivery problem.

Things that have helped:

Replace those 20 year old fuel lines.  There is no way that they are solid anymore.  Crap breaks free and clogs the carb.

Ethanol free gas.  Always and without exception.  Easy to find here where outboard fishing motors have the same problems.

Flush out the fuel pump.  Replace it if it doesn't give an impressive push of fuel.

Clean out the shut off valve at the tank outlet.  There is a little screen that can clog.

Clean the carb.  Then clean it again. A carb kit with new seals, a new needle valve and a new float is avavilable from Sears for about $20.

I've been able to take off the top half and clean out the bowl on the tractor most times, but I'm ready to take the whole damn thing off and soak it for a day in carb dip.

Get a spare carb.  The ultimate solution in my opinion.  Pop the new, clean one on, take the old one off to deal with later, and get back to work.

[TheMooseIsLoose 6]

I always use high test with Seafoam, this helps

[Forest Road 594]

You've had it for 10+ years? If you plan to keep it for another 10+ years this should be easy.

Replace all fuel lines & filter $5-$10

New fuel pump. Stens or Kawi $20. Identical to Onan OEM.

Clean the carb. Hopefully its just dirty.

If ethanol free gas is available in your area I strongly suggest you use it. It costs me about $1 more per gal vs super.

Edited February 2, 2015 by Forest Road

[Kurt-NEPA 755]

Hi Forest Road,

 

Do you have a source or part number for that Stens fuel pump?  My 520H could use one and I hate paying Onan prices.

[P3x 54]

Purchased a 520 about 4-5 years ago and was running into a lot of running issues.  Being new to WH tractors did the typical TS items, started using Sea Foam as recommended on this site. Was hesitant to take the top carb body off to clean it internally as I could not find a vendor that sells just the carb body gasket and did not want to pay the price of a complete carb OH kit to get one. Would get it running OK, only to have the RPMs hunting/engine running rough a couple of week's later.

 

Went to the local Cummings/Onan dealer to check on Carb OH Kit prices and the Parts guy recommended a spray cleaner (Onan) their mechs used - "4C" (Combustion Chamber & Carb Cleaner). Spray it in the carb with no disassembly required. Having tried many miracle "Mechanic in a Can" products over the years figured I'd buy a can to try as Onan part prices are steep.  Amazing stuff.  When ever it starts running rough/RPMs start hunting (which seems to be often for P220Gs) this cleaner has resolved the issues without taking anything apart other than removing the air cleaner housing. Sounds like a good deal for all 520H owners suffering from dirty carbs - Yes?  Now the bad news, Cummings/Onan stopped making/selling it with no equivalent product.

 

Searched the web and cannot find any info about it available - suspect it may be due to government regulations.  Posting a picture of one of the last cans I have to rule out it was only a dream...  Hope someone can shed some light on this mystery and knows a source I can find more to quench my addiction!

 

 

 

P3x