520h hunting only when hot at WOT

[520Tom 0]

I'm new to the forum and there may be some information about this here somewhere that I just don't know how to find. I appreciate any help you can give.

I have an '89 520h. Starts and runs fine runs at 3400 rpm WOT. Once it gets good and hot, after about 10 minutes

it starts gov hunting. Fine at Idle, but not good at WOT under load. I've cleaned the card 3 times. Cleaned it completely during a de-carbon and valve adjustment then twice after just from the top of the carb without removing the intake etc. Still the same issue.

Fuel pump seems to be pumping good. new filter.

I'm not familiar with how the gov works and don't know which way to go from here...

Anybody have any ideas on this?

Thanks

[smoreau 658]

Sounds like there is a pluged passage in the carb, Try slowly adding some choke to see if it gets better. If so you may need to go farther into the carb, Carb kits for these are not cheep! just to let you know. Also how old is the fuel? take a flashlight and look into the bottom or the tank and look for water, dirt etc. Your pump may be working, but the filter in the bottom of the tank may be pluged.

[P3x 57]

Soon after I purchased my 520, I had hunting/surging issues. Not knowing much about them I went through the govenor/carb linkage connections. Through vibration, one of the spring ends had worn into the balance bellcrank (not the correct name) and had a burr where it would hang up on as it rotated. Polished it out and that took care of the interferrance. But alas, did not solve my surge problem.

Could not purchase just the carb body half gasket and think the OH kit was 145.00 (Ouch). Picked up some of the Carb Cleaner (Foam) recommended by the local Onan dealer and it took care of the surging without having to open up the carb. Been running good since.

[SAM58 30]

Could not purchase just the carb body half gasket and think the OH kit was 145.00 (Ouch). Picked up some of the Carb Cleaner (Foam) recommended by the local Onan dealer and it took care of the surging without having to open up the carb. Been running good since.

Do you have a link to this Foam Carb Cleaner??

Had my 520H out last weekend, and it surged for the first time Until it warmed up. So I see a need to clean the carb coming.

thanks

OH....

Are you talking about SEA FOAM???

[Norlett 3]

we've had this type of problem.In our case it was a blocked jet.

It was the long jet in the carb.Its a very fine hole.We took it out and got it warm over a small flame.

Not to hot. Then a air line and some carb cleaner.Two or three goes.And since it's been ok.

Some of our fuel over here.Seems to gunge up if left to long.

Any idea's are worth a try.. :greetings-wavegreen:

[P3x 57]

^{The Carb Cleaner I referred to is not Sea Foam. It is an Onan product called "4C" Combustion Chamber & Carbuetor Cleaner. Has the following number on the can - No. 326-5278.}

^{Best Carb Cleaner I've ever used.}

[wallfish 18,172]

I can't read that last post

[520Tom 0]

Worked on this more today. Removed and cleaned the tank checked the fuel inlet elbow at the carb.. Same. A freind of mine suggested I check the fuel cap vent by removing the cap it when it occurred. Problem solved. Bad vent on fuel cap.

Thanks for your suggestions. i was starting to think it was not fuel related.

[can whlvr 994]

nice when its that easy,clean out a small hola and good to go