surging

[jpmcleod 4]

I have a 20 HP Onan and for the life of me, I can't get it to quit surging. I have changed the carburator, fuel pump, filter, drained the tank for debris and the fuel filter is allways full of gas, so I know I have gas flow. Can anyone give any suggestions as to what the problem may be. I get it fixed and it runs great for three or foud days and it begins to surge again. I have to run the choke on about 1/4 to keep it running. Beat me!@!

[Kelly 1,028]

Intake gaskets? I know you have to pull the intake to change the carb. did you put new ones in?

[brybrychrismer 17]

imo it sounds like a govner gear is sticking.

bryan

[jpmcleod 4]

Kelly. I did change out the intake gaskets when I installed a new carburator. I sprayed WD-40 around the gaskets to see if they were sucking air. I did not see any evidence of that. I plan on redoing all the gaskets again and boil out the new carburator. U use these two tractors in the orange grove, with the other one a 18 HP Briggs. I have had absolutely no problem with the Briggs.

I have 6 WheelHorses and I don't use any of them in the dusty grove.

Bryan. I will also check the gonenor as it does osolate causing the engine to rev up and down.

Thanks for the replys. I will let you know the cure, hopefully.

[Raider12 13]

It does sound like an air leak. (vacume leak). Try something like starter fluid around the carb base and intake area. It would rev up fast if it sucks it in.

[stevasaurus 22,292]

My HT55 Tecumseh did that...turned out to be adjusting the governor linkage.

Not sure what the linkage on the Onan looks like, but could have something to do with it.

Just a thought...you said the filter was full of gas. It should not be full if the filter is flowing correctly. It should be at a level just above what would drain out toward the carb... I hate to ask this...you know there is an in and an out on the filter if it is an inline?

Hope that helps.

[jpmcleod 4]

Steve. Good question. I learned the hard way which is the intake and the exit side of the fuel filter. I guess I should have said the filter has visable gas in it indicating gas flow. It really is not full but I am glad you asked. Believe me I have installed the backwards.

[TT-(Moderator) 1,129]

I can't imagine it being the governor if choking it helps, but here is the instructions:

Did you happen to check the in-tank strainer screen above the fuel shut-off valve? :omg:

[Herbl 10]

I know you said you replaced the carb but are you sure the replacement carb is any better than the original? I have a 520-H also with the same problem and I also cleaned the carb or so I thought. After my first cleaning it was doing the exact same thing, surging and the choke would smooth it out. I'm into Classic Cars and one of my car friends is a Toro Tech and he told me what to do. Take the top of the carb off and use carb cleaner and squirt it down every hole you see, if you look down the ventura you can see 3 tiny holes above where the idle screw comes out, they are air bleed valves and they are tiny and they get clogged. Just keep squirting carb cleaner till you see it coming out of these 3 holes and your surging will be gone, I hope this helps it sure did me...

[854WH 0]

make sure the oil isnt over full because on my kohler command 16 hp i overfilled it by accident and it started surging

[72morph 1]

I had the same problem on a sears 16 onan ,had to buy a float $34 to fix this.Does yours have the black compsite float?They get soaked and start to sink and will drive you to many bad deeds you normally would not do on a good day.Then you cannot adust them high enough because the gasket is wrinkled and interferes with the top of the float.Good luck and try to not go nuts.

[jpmcleod 4]

I am impressed with the response and I appreciate them all. I did not get home in time yesterday to try to fix the problem. I plan on taking this Thursday off and try to work on the tractor. I have printed all the replys and plan on trying each until I find the problem.

One response has me thinking. In regards to the overfill of oil, I have a small amount of oil residue in the bottom of my air cleaner. I don't believe the oil level is overfiled but that will be the first thing I check.

TT. Thanks for the governor print-out. I never knew how to adjust it.

You guys are a great source of information. My tractors are my hobbie especially my 6 Wheel Horses but sometimes my hobbie become an obsession trying to get or keep 12 tractors running perfect, but I keep trying.

[stevasaurus 22,292]

I know I am sure interested in what you find out with your tractor. Surging seems to be a fairly common problem talked about. Please let us know what you find wrong.

On a side note, you mentioned 12 tractors. I went back and searched and found that you have not yet posted any pictures. !2 tractors and no pictures. especially in Florida. You know what I am going to say... Thanks in advance.

[Don1977 604]

I would vote for a new float. I have a 8 HP Briggs thats doing the same thing. If it had

a brass float that was adjustable I could fix it. I hate plastic junk. The old Wheel Horse Dealer that I bought my tractor from had a saying " The road to hell is paved with plastic". I believe we are almost there, but I'm going to try a new plastic float to see if I can get it fixed.

[jpmcleod 4]

Took the carburator and intake off yesterday. Put new gaskets on the intake and cleaned the carb. Put it back together and it runs great. How long, I don;t know. It has the plastic float and I wish it had the brass but that's the way it goes. Thanks for all the help.

I have another that want idle and that is my next venture. Thank goodness it is a Kohler.