Wheel Horse 416H engine troubles

[JerryLook 78]

I have a 416H with the Onan P216. I got this tractor with about 500 hours on it, and ever since I’ve owned it I’ve had to run it at about half choke. Otherwise it had a surge that seems to be common with the Onans with bad intake seals. I’ve read about the intake needing to be resealed and tucked that away into memory for another day. 
 

Ever since the fall the tractor has been running worse and worse. I would be using it and it would randomly die. Other times I use it and it start surging.
 

At this point it runs terrible. The choke has to be all the way out, and it surges/hunts for an idle all the way from almost dying to the correct throttle setting. Basically it’s unusable right now. 
 

Things I’ve replaced recently to try to fix this. I’ve changed parts once at a time to see if the problem resolves….
 

-Fuel lines from fuel tank to carb 

-Fuel pump 

-Fuel pump impulse line 

-Fuel filter 

-Air filter

-Spark plugs 

-Resealed intake manifold and replaced   gaskets 

-New carb 

 

Since it has to have the choke all the way out I assume it’s a fuel problem. I can see fuel pulse in the filter, and I’ve taken off the line at the carb and can see fuel pumping from there. 
it does seem to go away completely at times. Although more often than not it runs terrible like right now. 
 

Any ideas? 

[JerryLook 78]

Could it be a governor issue?

[Wishin4a416 2,409]

I had an 18 on a JD that did that and ended up being a soft plug type of thing. I cant remember the correct name of it. It got blown out somehow. Ran good after replaced. Welch plug????

[JerryLook 78]

The Welch plug is on the carb right? I’ve replaced the carb but still have the old one. I wish they were easier to swap around on p216. It sucks having to remove the intake to remove the carb 

[JerryLook 78]

I’ve been doing some reading, and one thing I didn’t do is check the screen at the bottom of the fuel tank. I am getting fuel flow at the filter, but maybe not enough?
With the clear filter I can see the gas pulse every time the engine turns over. 

[lynnmor 8,397]

Have you checked the compression?

[JerryLook 78]

I haven’t checked compression but I can. 

[Bill D 2,515]

Make sure the throttle and choke are wide open when running a compression check.  Should be about 120 psi per cylinder. 

 

How did you reseal the intake?  Did you split it to reseal it and bolt it back together, or spread sealant outside along the seam?  Did you use OEM gaskets when reassembling?

 

 I'd rather rebuild an OEM carb than use an aftermarket as they are notoriously unreliable.  Then often cover several different engines and not correctly. Pictures may be helpful if you have them.  Don't give up on it. The P216 is one of my favorite engines.  I have three of them.  Great engines when running correctly.

Edited yesterday at 12:38 AM by Bill D

[JerryLook 78]

Yes I split the manifold and used fuel safe RTV to put it back together. I drilled out where it was held together originally (pins or some kind of rivets?) and used screws/nuts to hold it together. I used new gaskets for the intake/head joint and also for the carb. 
 

I’ll do a compression check on it this weekend. I still have the original carb. Since the new one didn’t fix the issue I might as well clean the original and reinstall it. 

Edited yesterday at 12:51 AM by JerryLook

[Brockport Bill 2,179]

lots of smart people on here to help but one sugegstion i have learned that i did not read in your thread is in addition to fuel valve screen??  if the gas gap is venting adequately? Remove the gas cap while running to see if that corrects issue? - -good luck

[JerryLook 78]

I removed the screen from the fuel tank since I’m running an inline filter. I pulled the fuel hose off the tank shutoff valve and let fuel run out. It has good flow. 
 

I’ve tried removing the gas cap while it’s running and it makes no difference. 
 

I cleaned the old carb and reinstalled it this morning. I’m getting pretty quick with changing the carb out. Curse you Onan for requiring the intake to be removed to change the carb!

 

Anyways, same thing is happening. It only runs with full choke on, and in about 15 seconds it will come up to a normal, healthy sounding idle, and then almost dies, then comes back to a normal idle. You can see the governor spring trying to keep it in check. 
 

When it is on the upstroke of the surge it sounds like it’s running good and clean. 

[kpinnc 16,676]

Might be worth trying a low pressure electric fuel pump. 

 

I have several Vanguard engines, and they have a common issue that affects how pulse fuel pumps work. The side oil pan gasket will sometimes develop a small air leak and the case pressure overwhelms the vent, so any pulse pump had way too much pressure which in turn overwhelms the carb float. The engine runs great until you move it. Anyway the factory fix is a very hard to find oil pan gasket. I added electric fuel pumps to mine and never had any issues again. 

[JerryLook 78]

It would be nice if there was a fuel pump test for these. Besides just seeing if the fuel is pulsing out. 
 

I know on the Ford 8N tractor there is a test where the fuel line disconnected at the carb should fill a pint jar in so many seconds. Something like that…. Just to check the flow rate 

[JerryLook 78]

Looking at the manual for the P216 engine, these things are listed under the symptom “governor hunting”

 

-Lean fuel mix 

-Dirty carb

-Dirty fuel filter 

-Bad fuel pump 

-Valve or seal leaking 

-Throttle linkage issues

-Governor spring issues 

I’m going to dive into it tomorrow again and see if I can figure it out. 

[steelman 254]

I had the exact same issues as you described on a 416-8. It sat around for several years and last spring I used a thread from RS site to disassemble and clean the carb good. It now runs like a champ! I used to think I would get rid of it once I got it running, however it is now my go to unit for plowing snow in NW Ohio. Love the sound of a good running Onan.