Onan P216 surge and carb settings

[WildmanC120 613]

I have a 416 that had a mild surge.  I removed the intake, took it apart and resealed it.  I took the carb apart and cleaned it in the ultrasonic a few times.  Still couldn't get it to stop surging. 

 

Recently bought another new/used intake and sealed it using another method, new p220 carb and all new gaskets.  Still surges.  

 

I was able to open up the screw on the side of the carb a few turns and got it to mostly stop. How far is too many turns?  What else do I need to check to get this to stop?  Engine only has 520 hours.  Begining to hate the onan

[WildmanC120 613]

Anyone? I'm about 3.5 turns out. 

[tom2p 2,393]

3 hours ago, WildmanC120 said:

Anyone? I'm about 3.5 turns out. 

3.5 turns sounds like it could be excessive - but I've never touched carb on P216 Onan 

 

( when I think carb screws ... idle mixture etc - I often think 1/4 turn ... 1 1/4 turns ... 2 1/4 ... )

it's possible there is a leak - or a carb passage or jet or whatever is slightly clogged or compromised 

 

if you spray carb cleaner or wd-40 around the intake - does the engine rpm increase ?

 

might also be a good idea to check the plugs and ensure not burning too lean 

 

apologize cannot assist more  - fortunate have not had issues with 416-H 

 

have one 416-H with around 1000 hours and no issues - and just got another 416-H this past summer (with 500+ hours ?) and no issues so far 

Edited January 28, 2020 by tom2p

[WildmanC120 613]

I'll have to give the carb cleaner around the intake and stuff a try.  

 

I've been messing with this thing for a few weeks now and driving me crazy. 

 

It's on the 2nd intake now that I have split and resealed, new 520 carb, all be intake and exhaust gaskets etc.

 

It had a mild surge before I did all this and now....still surging. I had to remove the cap off the screw on the carb to turn it out more to get it to "almost stop surging".  This thing is really making me hate Onan. Might just junk it and put a harbor freight predator 22hp on it and be done with it. 

[richmondred01 2,202]

The p216 carb isn’t the same as the p220 carb.

 

Edited January 29, 2020 by richmondred01

[WildmanC120 613]

16 minutes ago, richmondred01 said:

The p216 carb isn’t the same as the p220 carb.

 

 

I know.  It ran worse with the 216 carb I have that came off of it.  I bought the 220 carb because it was new.  

 

[richmondred01 2,202]

I honestly don’t understand.

just because it’s a new carb, it’s still the wrong part for the application.

 

[WildmanC120 613]

16 minutes ago, richmondred01 said:

I honestly don’t understand.

just because it’s a new carb, it’s still the wrong part for the application.

 

 

That is a true statement but I would imagine that it should run ok without surging. Best guess of course. 

[tom2p 2,393]

also make sure fuel supply / pressure is adequate 

[WildmanC120 613]

28 minutes ago, tom2p said:

also make sure fuel supply / pressure is adequate 

That I know is good. I installed a facet electric pump. 

[lynnmor 6,762]

The repeated attacks on the carburetor apparently will not resolve the issue.  Always start with a compression check, then valve adjustment so that you know the engine is healthy.  You might have a governor problem, but you need to explain "surging", we don't know if the engine speeds up more than expected or if it will not hold the set speed.  With a good explanation of the issue, or a video, maybe we could be of help.

[richmondred01 2,202]

Lynnmor is right. Check all the boxes he said. If it’s still surging, get with me I’ll send you a rebuild p216 carb to try out. 
if it works, great. If not, send it back to me.

[WildmanC120 613]

29 minutes ago, richmondred01 said:

Lynnmor is right. Check all the boxes he said. If it’s still surging, get with me I’ll send you a rebuild p216 carb to try out. 
if it works, great. If not, send it back to me.

 

I'll see if I can tinker with it on Friday. Take some video and check for leaks.  I am unsure about setting the valves on this though.

[richmondred01 2,202]

The intake should be set at .005", the exhaust to .013".
you may also want to get new valve cover gaskets, intake manifold and exhaust gaskets.

be careful removing the exhaust bolts. Don’t use a impact gun. At times they can be difficult to remove. You don’t want to shear them.

[WildmanC120 613]

33 minutes ago, richmondred01 said:

The intake should be set at .005", the exhaust to .013".
you may also want to get new valve cover gaskets, intake manifold and exhaust gaskets.

be careful removing the exhaust bolts. Don’t use a impact gun. At times they can be difficult to remove. You don’t want to shear them.

 

I have another set of intake and exhaust gaskets. I ordered 2 sets recently and replaced both when I had it apart.  I was able to get the bolts out without breaking them.  I cleaned up the threads and got new bolts and used a little never-seize to keep them from getting crappy again.

 

Where do the Pistons have to be to set the valves?  Just rotate engine over until valve is shut and loose? 

[richmondred01 2,202]

TDC.

[WildmanC120 613]

25 minutes ago, richmondred01 said:

TDC.

At TDC I can adjust both intake and exhaust? 

[richmondred01 2,202]

Yes

[lynnmor 6,762]

To be sure that the cam is in the correct position to adjust the valve, simply rotate the crankshaft till the valve is at the full open position and then rotate the crankshaft one full turn.  This removes all guessing.

 

[WildmanC120 613]

4 hours ago, lynnmor said:

To be sure that the cam is in the correct position to adjust the valve, simply rotate the crankshaft till the valve is at the full open position and then rotate the crankshaft one full turn.  This removes all guessing.

 

 

Thank you. Will do 

[oilwell1415 563]

Another vote for check the governor.  If they get dirty or in a bind they will let the engine slow down too far before opening the throttle and then they open it too far and the cycle goes on and on.

[WildmanC120 613]

18 minutes ago, oilwell1415 said:

Another vote for check the governor.  If they get dirty or in a bind they will let the engine slow down too far before opening the throttle and then they open it too far and the cycle goes on and on.

How do you do that? 

[oilwell1415 563]

Just look at all of the pieces and make sure they are clean and not in a bind.  It's not uncommon for the linkage to get tweaked a little bit when removing the carb and that can be all of the binding it takes to cause a problem.  Sometimes some oil residue will get on there and start attracting dust and once it starts accumulating it just keeps going until it causes problems.

[WildmanC120 613]

OK, Had a few minutes today to look at this.  I fired her up and did the spray test.  Didn't notice anything with that.  Found that if I close the choke flap a little on the carb that it would fix the issue with still leads me to believe its a fuel problem. 

 

I also removed the plugs and performed a compression check.  Engine looks and sounds very healthy to me.  I'm not sure I need to do a valve adjustment at this time.  It might just complicate things honestly. 

 The first 3 photos below are of the rear cylinder and the last 3 photos are front cylinder. 

 

P216 Running

[lynnmor 6,762]

The vacuum port in the intake next to the carb appears to be OK and closed, just make sure it is not drilled thru.  There is a welch plug next to the idle mixture screw, make sure it is there and sealed.  Make sure that you didn't use E15 or E85 fuel.  The spray you are using evaporates so fast that the test may not be valid, try again with some oily spray or just plain oil.  Are you using the correct Champion spark plugs?  That black/white contrast is extreme.   A valve that has near zero clearance will show an excellent compression test, but the clearance will quickly go away with just a little warm up.  It sure does seem like it is sucking air.