Jump to content
Kurt-NEPA

My 520H has gone hunting - needs some help

Recommended Posts

Kurt-NEPA

I've had my share of 520H surging problems, but now I have a new one.  Its hunting.  This is my 1988 520H with the Onan P220.  It starts up just fine.  I begin mowing and all is well is for about 15 minutes, then it starts hunting or surging (if you wish).  It only happens under load (PTO engaged with a 48" SD deck) and after the tractor warms up completely.  The rpms start to drop, then the governor opens the throttle until the rpms are back up, throttles back as it should, then the rpms drop again and the cycle repeats on about a 30 second interval.  Its almost like the the governor is way too slow in reacting.

If I disengage the PTO, the big Onan runs just fine and I can get it back to the stable without issue.  I've repeated this about 4 times now.

 

What I've done so far.

1.  Carb was cleaned about 3 weeks ago.  (My usual spring chore)
2.  I changed the oil and filter, blew out the fins, and cleaned the air filter
3.  Installed a new electric fuel pump.
4.  Checked the plugs, they look just fine and are properly gapped.

 

So I thought, I must be the new electric fuel pump.  So I disconnected it and put the gas lines back on the stock pulse pump.  Ran the tractor and had the same problem.  So its not the pump.

I've had carb cleaning fix an idle surge many times and I plan to clean this carb again.  I would put in a kit if the price wasn't so darn high.  

 

Any other ideas?

 

Thanks,

Kurt

Share this post


Link to post
Share on other sites
 
Pollack Pete

Any of my Onans that had the surging / hunting problem was crap in the carb.Clean the carb again.Do you have an in-line fuel filter?A must have in my book.I also use nothing but ethanol free gas.BTW,does the surging go away when you close the choke a little? If so,a gas problem for sure.

Share this post


Link to post
Share on other sites
 
Tankman

Grandsons and I visit our local airport once 'n awhile.

 

100 octane, low lead, ethanol free gas. Don't always use the ethanol free gas but, it does wonders keeping the carbs clean and purring.

 

Berrymans is used when we have gas with ethanol (https://www.berrymanproducts.com/?gclid=Cj0KEQjw3-W5BRCymr_7r7SFt8cBEiQAsLtM8l8i-zX33jA9uYPj3CyyhwfptMlGFuvCM4YPiyIl-7EaAgAj8P8HAQ)

Share this post


Link to post
Share on other sites
 
Kurt-NEPA

Thank for the the replies.

 

Yes, I always use fuel filters.  This one is about a year old and has about 20 hrs on it.  (Toro filter)

 

I wish I had the option to use non-ethanol fuel.  None available locally.  I've heard a rumor that a station about 45 miles away is starting to carry it.  I'll be checking it out.

 

I'll be doing some troubleshooting this afternoon, I'll put on a new fuel filter, clean the carb (again), and warm it up.  I'll be checking for intake manifold leaks and will check for better operation with the choke open (thanks for the suggestion).

 

I'll see if I can find some Berrymans (thanks for the tip)

 

Tankman - I'm glad some else knows AVP.  Since its recent upgrade its become a very nice airport.  Too bad many of its flight have to go through PHL.  I've made many a mad dash to Philly when my flight was cancelled..

 

Kurt

Share this post


Link to post
Share on other sites
 
wrightorchid

If you have any fishing areas, it is also sold as marine gas.  Good luck.

Share this post


Link to post
Share on other sites
 
lynnmor

Look where the intake manifold mounts to the block.  I once used cheap gaskets there and they completely failed.  If you pull the intake it might be a good time to adjust the valves.

  • Like 1

Share this post


Link to post
Share on other sites
 
WHX??

Try some seafoam or Marvel's... Kurt....it can't hurt. Gotta be a fuel issue or a piece of varnish in a jet. I had the same kinda issue but then it went away mysteriously so never did find out what it was.

Share this post


Link to post
Share on other sites
 
Kurt-NEPA

Thanks for the replies, they all give me things to try.

 

I went out this morning and replaced the fuel filter, and did a quick - from the top - carb clean.  I didn't see anything plugged or even a little bit dirty.  Yes, I did pull the downward jet rod and clean it.

 

The tractor fired right up and ran nicely.  I started to mow, about 1/2 hr. later the hunting started again.  I tried adding some choke and the hunting seemed to improve.  The best spot seemed to right before the engine bogged down.  I also opened the fuel cap in case the vent was block, it did no good.  One the hunting got a bit better I kept mowing and slowly backed the choke off.  Now the engine is running just fine, so I continued and for about 10 minutes..  Then the hunting came back, this time the choked did not help.  I gave up after another couple of minutes.

 

When I got back to the stable I did the unlit propane torch check around the intake manifold.  No changes noted so I think that is tight.  I had pulled that manifold about 20 hours ago to fix an intake leaks, so the gaskets are fairly new.  I did adjust the valves then.

 

I'm running out of ideas, the only thing I can think of is to try some Sea Foam, Marvel, or Berrymans.  If that doesn't work, I'll pull the carb and it let it soak in a carb cleaner can for a day or so.

 

I'll be traveling for the rest of the week, so I won't get to work on it.  It will give some time to think this thorough.  I hate to be on the road when a problem waits for me at home.

 

Thanks for all the help, I'll keep you posted. Time to go out and finish mowing with my other 520H. 

 

Kurt

Share this post


Link to post
Share on other sites
 
pfrederi

Drive up to NY many Mirabito Gas station have ethanol free hi test.

Share this post


Link to post
Share on other sites
 
WVHillbilly520H

My thoughts on the Berryman B-12 is that it is just as good as Seafoam but half the price at $3.19/can @Wal-Mart vs $7-9/can Seafoam and does the same thing with the same basic ingredients but I'm a cheap ole hillbilly, Jeff.

  • Like 1

Share this post


Link to post
Share on other sites
 
DoctorHfuhruhurr

This site may help you locate some ethanol free gas locally and of course there's a related phone app.   http://www.pure-gas.org/index.jsp?stateprov=PA

 

 

  • Like 1

Share this post


Link to post
Share on other sites
 
TDF5G
14 minutes ago, DoctorHfuhruhurr said:

This site may help you locate some ethanol free gas locally and of course there's a related phone app.   http://www.pure-gas.org/index.jsp?stateprov=PA

 

 

Thanks for posting the link.  I am very surprised to learn the HY-VEE stations in my area are ethanol free.   

Share this post


Link to post
Share on other sites
 
lynnmor

I am no fan of ethanol, but your Onan will run OK using it.  The later models run lean and often backfire when shutting down.  The various additives mentioned might dissolve some forms of blockage but I find it is almost always necessary to just physically remove it.

  • Like 1

Share this post


Link to post
Share on other sites
 
cheesegrader

TIme for the dreaded "off engine" carb clean.

I know people get by with spray cleaning the carb with the top disassembled, 

but it just doesn't work for me.

Bits of 20 year old fuel line or gasket just won't get removed this way.

Take it off, soak it overnight, blow it out with compressed air, then do it again.

It is a PIA, but it works for me.

  • Like 1

Share this post


Link to post
Share on other sites
 
sluggo

Make sure that all the wires are pushed snug into the ignition switch. My PTO was cutting out and this was the problem. The price is right and the amount of effort is right. 

 

 

Hope this helps.

Share this post


Link to post
Share on other sites
 
Kurt-NEPA

Thanks for all the comments,

 

The search for Non-ethanol gas begins.  I wish we had something local. That crap gas just took out my 5 year old Stihl line trimmer.

 

Cheesegrater, you are so right about " the dreaded "off engine" carb clean"  but I think that is what I have to do.  What a PIA. So that is the plan when I get home.  Time to order gaskets.

 

Sluggo, I like the comment about the ignition switch.  When I installed the electric fuel pump I tapped off the "R" terminal of the ignition switch to fire the FP relay.  Maybe I jarred something loose.  I have a new switch in stock, so I think I will try that first and see what happens.  Then its off to the dreaded "Carb Clean.

 

I'll probably do both.  I also had a suggestion to inspect the screen on the valve inside the fuel tank for crud.  That is on the list too, I'll just replace the valve.

 

Thanks Guys,  I'm getting lots of things to check when I get home on Monday.  Did I mention I hate travel.

 

Red Square is fantastic

 

Kurt

 

 

  • Like 1

Share this post


Link to post
Share on other sites
 
WHX??

Let us know where you get the gaskets... mine's gotta be done too :( 

  • Like 1

Share this post


Link to post
Share on other sites
 
Kurt-NEPA
13 hours ago, WHX61/3 said:

Let us know where you get the gaskets... mine's gotta be done too :( 

 

Sometimes I go to onanparts.com, but more often I get better prices on Ebay.  Search Onan and the Onan part number.  I found all 3 gaskets there easily, but the price is still ridiculous.

 

I've got to try Boomer one of these days.

 

Share this post


Link to post
Share on other sites
 
WHX??

Thanks Kurt.. I was gonna go see Boomer too.... prices be damned just cause he's a member here

Share this post


Link to post
Share on other sites
 
onanparts.com
15 hours ago, WHX61/3 said:

Thanks Kurt.. I was gonna go see Boomer too.... prices be damned just cause he's a member here

Careful....ya never know who might be listening....:)

  • Like 3

Share this post


Link to post
Share on other sites
 
WHX??

Hello onanparts guy and :WRS: Glad to see you jumped on the supporter wagon too! :handgestures-thumbupleft: Just checked out your website and it looks like you have quite a few things to offer us Onan owners. What took you so long to find us!?!?  Maybe you should talk to one of the mods about getting in the vendors section.

  • Like 1

Share this post


Link to post
Share on other sites
 
WHX??

Hello onanparts guy and :WRS: Glad to see you jumped on the supporter wagon too! :handgestures-thumbupleft: Just checked out your website and it looks like you have quite a few things to offer us Onan owners. What took you so long to find us!?!?  Maybe you should talk to one of the mods about getting in the vendors section.

Share this post


Link to post
Share on other sites
 
Dans wheelhorse

I'm curious how this pans out.

Share this post


Link to post
Share on other sites
 
onanparts.com
15 hours ago, WHX61/3 said:

Hello onanparts guy and :WRS: Glad to see you jumped on the supporter wagon too! :handgestures-thumbupleft: Just checked out your website and it looks like you have quite a few things to offer us Onan owners. What took you so long to find us!?!? 

Hello WHX61/3,

Found RS years ago, but an unanticipated move by RS from one host to another zapped many user ID's and PW's, this was back around 2011 or so. Located some fresh batteries for the flashlight and found our way back! :)

 

If you take a peek at this thread you will discover some interesting info I've been working on here at RS. :)

 

  • Like 2

Share this post


Link to post
Share on other sites
 
WHX??

Hello Onan guy

Those production orders are interesting in the fact that some go back as far as '68. I am thinking that may we should see if we could get @gwest_ca to get those in a downloadable .pdf for the files section if there not already there. Or at least pinned somewhere. Might be handy to know what WH wanted on a particular series, especially in the late '80's - early '90's which I believe is what many of our members have.

 

I will be calling for parts when the honeydo list gets short enough to let me start trying to figure out what my 220 cold start problem is. :)

 

Sorry for hijacking the thread Kurt! :)

Share this post


Link to post
Share on other sites
 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...