Intermittent rogh running P220G

[pennsdalerepairshop 0]

Guys:

This P220G Onan in a WH is driving me nuts! Started running rough under load a little while back. Removed the carb, disassembled, soaked for a long while in NAPA carb solvent. Replaced the accelerator pump with a new kit. Made sure all jets were cleaned, replaced fuel filter, drained and flushed tank (blew out entire fuel line as well). Replaced vac line to pump, checked pump for output (great!) Made sure intake was sealed OK. Air filter and precleaner fine. Added fresh fuel and reassembled everything. Engine runs better but every once in a while it will sputter, almost quit, then even out. Only really seems to do it under load (PTO engaged--manual). Checked for excess drag on system--spindles and pulleys fine. Belt tension OK. Every once in a while when starting up it emits black smoke like it's loaded up, but will even out. Also changed and relocated capacitor to cooler location.

This Nikki carb has no adjustments obviously. Thinking maybe the float level? Tried to replicate it under no load, doesn't seem to do it. Will do a little on an incline, but at other times even when under load and up the hill it's fine...

Hate to throw parts at it; maybe the float level? I know the float is good, but maybe needs adjustment?

Thoughts, please!!

Thanks!!

Tom

[MarkPalmer 81]

Have you done a valve adjustment on the engine? It will often solve intermittent misfire problems if all the other tune-up related items have been addressed.

-Mark-

[JackC 617]

Sounds like a carb problem.

I have a simpler carb on my 1989 520HC since it was before the emissions version and accelerator pump addition and it is adjustable.

How many hours on the engine?

Did you check valve adjustments when you had the carburetor off?

The heads should be de-carboned at least every 500 hours, some say 200 hours.

Also need to be careful not to over torque the manifold bolts on the aluminum engine and strip threads which will prevent proper sealing.

Maybe try closing off the vacuum port to the vacuum gauge just to eliminate a leak there as a possible cause?

[ericj 1,579]

could it be a safety switch causing the motor to cut out ? you said it only does it under a load witch is when the pto is engaged thus a safety switch check the connections on the pto switch, the seat switch i doubt that the motion control switch would cause this problem, just my thought

eric

ps you can sell it to me, also check compression hot and cold

[pennsdalerepairshop 0]

All:

Excellent suggestions...have not explored the safety switch issue...will check that as it only does it when it's under load. I'm leaning away from a valve issue, as it runs smoothly when the PTO is off. Vac lines are new.

Will keep you posted!!

Thanks!

Tom

[pennsdalerepairshop 0]

All:

I ordered two safety switches to replace the ones controlling the PTO and hydro lever. They seem to get the most use. When received and installed I will report what I find.

Any other thoughts and opinions out there are most welcome...

Tom

[ericj 1,579]

any updates for us ? did you get your 520 running again ? keep us posted

eric j

[pennsdalerepairshop 0]

All:

An update to the saga of the 520-H....Changed out the micro switches at the shift lever and PTO. Figured they saw the most use. That did nothing, although I started with another problem!! I swear that when I first got this thing it would continue to run if I set the parking brake and got off the seat. Now it shuts off when I get out of the seat (with the PB on), and the corresponding light comes on the dash.

Waiting now on a carb to replace thhis one and see. I hate throwing parts at things but I've checked and rechecked everything I can think of to no avail...started it on Sunday to move it around the shop; didn't even choke it, and it ran rougher than heck until I gave it full throttle for a few moments. Next time I pull the carb and manifold I'm going to check valve clearances again. but I'm convinced this isn't a valve train problem...

Any other thoughts out there are greatly appreciated!!!

[6wheeler 669]

I do not like "shotgunning" parts at a machine either. Maybe you might check electrical problems for loose or bad connections. 520's have their fair share of electrical gremlins and with all the safety gizmo's attached to em' , it'll show up from time to time . When it cuts out, does it puff black smoke like its loading up? If not? I really wouldn't lean towards fuel. Could be carbon build up, but I'd bet not. That would show up on top end run out by not having a clean burn and should make her lean out a touch. What do the plugs look like? Ashy? Side burned? I am still leaning towards electrical. Just my . Pat

[pennsdalerepairshop 0]

UPDATE!!!

I was able to purchase a NOS carb for the machine...put it on today. While I had it apart I checked valve clearances--all OK. Put the carb on and wallah!---ran like a new one. Could NOT get it to falter, stutter, or anything!

Thanks to all!

Tom :banana-tux: