1989 520H surging problem.

[TonyWH520H 6]

Hello, new member here with a first time post. Although I have read a bunch of info from here the last month after picking up my first wheel horse. 

 

I finally got everything sorted out to use it today. New belts for the PTO and deck spindles. The fuel pump wasn’t any good. So I wired a small electric one to a toggle switch. 1.5-3.5 psi. Smallest the I could find.  

The coul was not firing and I traced it down the the ignition module being bad. I ran a hot wire to the coil on a toggle switch also. Fired(s) right up and turns off with the toggle switch. It’s only until I can order a new module.  

 

What should I start checking for the surging issue? Would it have anything to do with the fuel pump not being there? Should I route the vacuum line to anything else? 

 

 

Everything else on it is it is perfect and I love the thing and the Amount of the that I can do with it(also for a plow, a disc and a tiller). 

[953 nut 51,397]

8 minutes ago, TonyWH520H said:

checking for the surging issue? Would it have anything to do with the fuel pump not being there?

          The port on the block that supplied pulsation to the fuel pump can be capped off.

The surging is probably caused by a vacuum leak and/or carburetor that needs to be rebuilt.

[WHX?? 46,633]

Hello Tony and 

Congrats on your 1st . Sounds like you might have the fuel supply thing ironed out but do a search on Onan Surging here and you WILL find a host of threads on this subject. Most often due to a dirty carb needing cleaning as Richard suggests or off governer settings. This is not an uncommon problem for the love/hate relationship we have with Onans.

[TonyWH520H 6]

9 minutes ago, 953 nut said:

          The port on the block that supplied pulsation to the fuel pump can be capped off.

The surging is probably caused by a vacuum leak and/or carburetor that needs to be rebuilt.

 I will cap it off tomorrow after work. Luckily I got an extra carb with the tractor. I will probably clean that one up tomorrow and throw it on in a day or two. 

[TonyWH520H 6]

6 minutes ago, WHX14 said:

Hello Tony and 

Congrats on your 1st . Sounds like you might have the fuel supply thing ironed out but do a search on Onan Surging here and you WILL find a host of threads on this subject. Most often due to a dirty carb needing cleaning as Richard suggests or off governer settings. This is not an uncommon problem for the love/hate relationship we have with Onans.

Thank you. The more I read about them the more I seem to like it. I have already started to look for some more attachments and the pullies that I need for the tiller and so on. Seems like it will be more love than hate so far lol. 

 

What do you mean by “governer settings”?   This is my first lawn tractor. Only push mowers before this. 

However I am a full time auto technician. So I have the tools and ability to forgive anything out if I get a point in the right direction. Just no experience with the small engines. 

[953 nut 51,397]

Not sure of your engine model but here is a link to Onan Service Manuals that should be helpful.

http://www.wheelhorseforum.com/files/category/14-onan-service-manuals/

Edited March 26, 2018 by 953 nut

[TonyWH520H 6]

14 minutes ago, 953 nut said:

Not sure of your engine model but here is a link to Onan Service Manuals that should be helpful.

http://www.wheelhorseforum.com/files/category/14-onan-service-manuals/

As far as I know it is the Onan engine still. How do I identify it? 

[953 nut 51,397]

Does it look like this? If so it is an Onan.

[SylvanLakeWH 24,033]

[daveoman1966 3,585]

I also had a surging problem with my 520.  Carb cleaning resolved the issue.  CAUTION...  the NEEDLE VALVE is in a precarious position and is easy to lose track of.  With the air cleaner off, here are a few pics of the carb and linkage. Use aerosol carb cleaner to flush out the float chambers.

[Ed Kennell 35,485]

After I decarbed mine, it surged badly.    It took three carb cleanings, but I finally got it clean and the surging stopped.   I believe dirt is sometimes scraped off the inside of the fuel lines when installed on the barbed fittings.   This immediately fouls the carb that was just cleaned.    Before cleaning the carb, it is best to clean the tank, install all new lines and run the engine with a clean concentrated Sea Foam fuel mixture. 

 

Almost forget,    Tony.       I am a little confused on the ignition module.  If it runs when you jump 12VDC to the coil, your ig mod must be OK.  Sounds like you have a wiring/ ,connector  problem which is quite common on these 520s.

Edited March 27, 2018 by Ed Kennell

[WVHillbilly520H 10,369]

You can get aftermarket Onan pulse fuel pumps off Amazon or eBay rather cheap, IMO just one less power draw on the stator, Jeff.

[ericj 1,576]

@TonyWH520H

11 hours ago, Ed Kennell said:

I am a little confused on the ignition module.  If it runs when you jump 12VDC to the coil, your ig mod must be OK.  Sounds like you have a wiring/ ,connector  problem which is quite common on these 520s.

If the ignition module goes bad one of two things happen, either the tractor runs and shuts off after a few minutes when it warms up, or it won't start at all. By jumping direct to the coil you have proven that the module and the coil is good. As stated above down load the demystification guide and go through it step by step till you figure it out, good luck

 

 

 

 

 

eric j