Onan P220 surging/hunting at operate

[Horse Newbie 7,069]

I am by no means an engine/ diagnostics guy, but before I adjust the carb I would spray some carb cleaner, a little gas, or some other flammable liquid in the carb to see if it would fire even for just a second...if it does that would tell you that you have a fuel delivery problem...

@lynnmor do you have any suggestions or tips before us rookies create more problems ?

Edited August 21, 2021 by Horse Newbie

[WheelHorse520H 708]

1 minute ago, Horse Newbie said:

I am by no means an engine/ diagnostics guy, but before I adjust the carb I would spray some carb cleaner, a little gas, or some other flammable liquid in the carb to see if it would fire even for just a second...if it does that would tell you that you have a fuel delivery problem...

@lynnmor do you have any suggestions or tips before us rookies create more problems ?

Thanks, I found the manual on how to adjust the carb, I am going to reset the air-fuel mixture screw by turning it in all the way then out 1 & 1/4 turns like the manual said. I do have fuel, I took the front spark plug out to test for spark while I cranked it and a geyser of gas flew out. Also when I crank it I can see fuel spraying out of the muffler when it won’t start.

[lynnmor 7,306]

21 minutes ago, WheelHorse520H said:

Thanks, I found the manual on how to adjust the carb, I am going to reset the air-fuel mixture screw by turning it in all the way then out 1 & 1/4 turns like the manual said. I do have fuel, I took the front spark plug out to test for spark while I cranked it and a geyser of gas flew out. Also when I crank it I can see fuel spraying out of the muffler when it won’t start.

 

 

Now we have some good information, the engine is flooded with gas.  I didn't look back to see the history on the carburetor, but it may have a serious issue.  To clean out the flooding, remove both spark plugs, disable the ignition to prevent a fire, then run the starter till the fuel clears.  It would be best if this was done outdoors well away from anything important.  Install the plugs and try to start it, if it runs briefly, shut it down and drain the oil since it contains gasoline.  With fresh oil and filter, try to start again, if it runs right you are done, if it runs real bad or not at all, don't keep trying, you will only do the same thing again.

 

[WheelHorse520H 708]

Ok glad you mentioned that, I am reassembling it. I counted how many turns the screw came out when I cleaned it and put it in the same amount but when I tried to do what the manual said an put it in all the way, it was already there.

Edited August 21, 2021 by WheelHorse520H

[WheelHorse520H 708]

It’s not running right even before I changed the oil. I think it is a carb adjustment, because when it first started it started at around half choke. It’s 84 degrees here in Kingston if that makes a difference.

[Horse Newbie 7,069]

Lynnmor was saying...with the flooded engine, there is too much gas in the cylinders, and  probably some gas in the crankcase oil too( this is bad, you don't want that)

To clear out the cylinders of too much gas, remove both spark plugs, disable the ignition, and crank the engine over to clear the cylinders/ combustion chambers of gas.

Put everything back together and try to start.

If if starts shut it off quickly...change the oil and oil filter to get rid of the contaminated oil in the crankcase. After the oil change try to crank it again... If it runs good then you are done...

 

If you understood Lynnmor, forgive me for this post...just was not sure you understood what he was saying...

[WheelHorse520H 708]

Just now, Horse Newbie said:

Lynnmor was saying...with the flooded engine, there is too much gas in the cylinders, and  probably some gas in the crankcase oil too( this is bad, you don't want that)

To clear out the cylinders of too much gas, remove both spark plugs, disable the ignition, and crank the engine over to clear the cylinders/ combustion chambers of gas.

Put everything back together and try to start.

If if starts shut it off quickly...change the oil and oil filter to get rid of the contaminated oil in the crankcase. After the oil change try to crank it again... If it runs good then you are done...

 

If you understood Lynnmor, forgive me for this post...just was not sure you understood what he was saying...

No, I understood, thanks for making sure that was clear, I thought change the oil if it started and ran good.

[Horse Newbie 7,069]

No matter whether it is running or not, change the oil...it's contaminated...

After you do change the oil do not continue to try and crank excessively if it wont start, and is still flooding...the severe flooding of the engine will just contaminate the fresh oil.

[WheelHorse520H 708]

Solved, bad fuel pump and the carb was adjusted correctly before. I was mistaken on it flooding. It only started and ran good at full throttle. 

[lynnmor 7,306]

4 hours ago, WheelHorse520H said:

 I do have fuel, I took the front spark plug out to test for spark while I cranked it and a geyser of gas flew out. Also when I crank it I can see fuel spraying out of the muffler when it won’t start.

 

You said this 4 hours ago and now you say it wasn't flooded, I don't know how to help.

[WheelHorse520H 708]

33 minutes ago, lynnmor said:

 

You said this 4 hours ago and now you say it wasn't flooded, I don't know how to help.

I totally get where you are coming from, but you have helped me so much already. I am thinking the geyser of fuel was stuff I kept adding to get it to start because the fuel pump wasn’t working. I also noticed even though I stabilized the gas it went bad so I am draining it. I also noticed I put the throttle cable spring in the wrong hole. Honestly most of this is my fault, I jump to conclusions and get excited to start it and don’t wait to get any opinions from you. I will try to make myself wait and more patient.

[WheelHorse520H 708]

It seemed to run better with fresh gas but because I was messing with the carb earlier it runs a little low at operate. Although, the paint on the exhaust is peeling again because I had to start it to tune it so I might have to paint that a third time now. With a different brand. It looks like some light tuning and we should be all set. Two more questions, the engine is supposed to operate at 3600 rpms correct? And the tachometer operates off of the Voltage regulator/rectifier, correct? Thanks for the 10 pages of knowledge and information that I have got from all of you.

[lynnmor 7,306]

44 minutes ago, WheelHorse520H said:

It seemed to run better with fresh gas but because I was messing with the carb earlier it runs a little low at operate. Although, the paint on the exhaust is peeling again because I had to start it to tune it so I might have to paint that a third time now. With a different brand. It looks like some light tuning and we should be all set. Two more questions, the engine is supposed to operate at 3600 rpms correct? And the tachometer operates off of the Voltage regulator/rectifier, correct? Thanks for the 10 pages of knowledge and information that I have got from all of you.

 

 

Correct and correct on your two questions.

 

Did you wash the muffler with soap and hot water before painting?  The surface needs to be clean, even oils from your skin can be a problem.

 

I wrote the following to help a member not long ago:

 

Was the welch plug missing?  Did you clean all the small holes behind it?  There is no adjustment for high speed mixture, only the idle mixture if it has a idle mixture screw.  To adjust the idle, do this:

 

1. Back off the idle adjustment screw located near the throttle cable.

2. Adjust the throttle stop screw for 1000 RPM.

3. Adjust idle mixture screw for the highest speed and best idle.

4. Readjust the throttle stop screw to 1000 RPM if necessary

5. Readjust the mixture if necessary.

6. Repeat steps 4 & 5 if necessary.

7. Adjust the idle adjustment screw near the throttle cable to 1200 to 1400 RPM.

8. Insure that the throttle cable pushes the lever to the stop, the speed should be 3600 RPM, bend the stop if needed.

[WheelHorse520H 708]

8 minutes ago, lynnmor said:

 

Did you wash the muffler with soap and hot water before painting?  The surface needs to be clean, even oils from your skin can be a problem.

No, I hadn’t even thought of that but I was wearing rubber gloves. I am not sure if that makes a difference.

 

9 minutes ago, lynnmor said:

 

Correct and correct on your two questions.

 

Did you wash the muffler with soap and hot water before painting?  The surface needs to be clean, even oils from your skin can be a problem.

 

I wrote the following to help a member not long ago:

 

Was the welch plug missing?  Did you clean all the small holes behind it?  There is no adjustment for high speed mixture, only the idle mixture if it has a idle mixture screw.  To adjust the idle, do this:

 

1. Back off the idle adjustment screw located near the throttle cable.

2. Adjust the throttle stop screw for 1000 RPM.

3. Adjust idle mixture screw for the highest speed and best idle.

4. Readjust the throttle stop screw to 1000 RPM if necessary

5. Readjust the mixture if necessary.

6. Repeat steps 4 & 5 if necessary.

7. Adjust the idle adjustment screw near the throttle cable to 1200 to 1400 RPM.

8. Insure that the throttle cable pushes the lever to the stop, the speed should be 3600 RPM, bend the stop if needed.

I will try that on Monday, getting some bad weather tomorrow.

[WheelHorse520H 708]

On 8/21/2021 at 8:48 PM, lynnmor said:

1. Back off the idle adjustment screw located near the throttle cable.

2. Adjust the throttle stop screw for 1000 RPM.

3. Adjust idle mixture screw for the highest speed and best idle.

4. Readjust the throttle stop screw to 1000 RPM if necessary

5. Readjust the mixture if necessary.

6. Repeat steps 4 & 5 if necessary.

7. Adjust the idle adjustment screw near the throttle cable to 1200 to 1400 RPM.

8. Insure that the throttle cable pushes the lever to the stop, the speed should be 3600 RPM, bend the stop if needed.

This is the screw and stop, correct? Also, I assume I do this with the engine running, correct?

[lynnmor 7,306]

8 minutes ago, WheelHorse520H said:

This is the screw and stop, correct? Also, I assume I do this with the engine running, correct?

 

That is the screw in step 1 & 7.

 

The screw in step 2 is on the side of the carburetor.

 

The idle mixture screw is accessed thru the muffler with a long screwdriver and a flashlight.  Four letter words are optional.

 

All of the screws are adjusted with the engine running.

 

The throttle stop is visible on the left side of your photo.

Edited August 23, 2021 by lynnmor

[WheelHorse520H 708]

1 minute ago, lynnmor said:

That is the screw in step 1 & 7.

Okay, thanks.

 

1 minute ago, lynnmor said:

The screw in step 2 is on the side of the carburetor.

Do you know where I get access to it from?

 

2 minutes ago, lynnmor said:

The idle mixture screw is accessed thru the muffler with a long screwdriver and a flashlight.  Four letter words are optional.

This is the one with the plastic cap, right?

 

2 minutes ago, lynnmor said:

All of the screws are adjusted with the engine running.

I thought so, how else would I know the engine’s rpm? Got it.

 

3 minutes ago, lynnmor said:

The stop stop is visible on the left side of your photo.

The tab under the throttle cable.

 

Thanks,

Andrew

[lynnmor 7,306]

Just now, WheelHorse520H said:

Okay, thanks.

 

Do you know where I get access to it from?

Flashlight an screwdriver on rear side of carb.

 

 

This is the one with the plastic cap, right?

Yes.

 

I thought so, how else would I know the engine’s rpm? Got it.

 

The tab under the throttle cable.

Yep.

 

 

[WheelHorse520H 708]

Thanks for all the help.

[lynnmor 7,306]

1 minute ago, WheelHorse520H said:

Thanks for all the help.

You're welcome.  I'll be out most of the day, good luck.

[WheelHorse520H 708]

Thanks, @lynnmor your directions worked wonders on this machine, just a little tweaking now that the air filter is back on. 

[WheelHorse520H 708]

I did all of the adjustments you suggested and it runs great… until I go up hill or engage the PTO. I don’t know what it happening, it runs good I engage the PTO and it slows down, the blades spin for a good 5-10 seconds and then it dies. No matter what I have to start it at 1/4 choke even though it’s not only warm it’s hot.

[lynnmor 7,306]

27 minutes ago, WheelHorse520H said:

I did all of the adjustments you suggested and it runs great… until I go up hill or engage the PTO. I don’t know what it happening, it runs good I engage the PTO and it slows down, the blades spin for a good 5-10 seconds and then it dies. No matter what I have to start it at 1/4 choke even though it’s not only warm it’s hot.

Screen or valve in tank.

Fuel hoses.

Fuel pump.

Fuel pump pulse hose.

Carburetor needs cleaned.

 

Take the hose from the tank off the fuel pump and lower it to a pan on the ground, you should get a steady flow of gas, not just a dribble.

[WheelHorse520H 708]

15 minutes ago, lynnmor said:

Screen or valve in tank.

Was completely clear when I drained the old gas on Saturday.

 

15 minutes ago, lynnmor said:

Fuel hoses.

I will check tomorrow, it is facing up hill at the moment.

 

16 minutes ago, lynnmor said:

Fuel pump

Not sure if it is working, filter does not fill with gas while running like it used to, could be a clogged line.

 

17 minutes ago, lynnmor said:

Carburetor needs cleaned.

Added SeaFoam for now, until I rule out the other things.

Thanks for the suggestions, I didn’t even consider fuel issue but it seemed odd the filter wasn’t full while it was running.

[Handy Don 12,230]

2 minutes ago, WheelHorse520H said:

filter does not fill with gas while running like it used to

On my tractor, the filter does not completely fill, more like ⅓ or ½ way. But I do see fuel sloshing around in there and steady squirts from the pump.