Mule flooding and won’t start

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Mule flooding and won’t start

Post by Cbrinker » Fri Aug 24, 2018 2:47 pm

My a5 mule has been sitting for at least 20 years and I am now trying to get it running. It has started and ran for about 10 seconds once and then flooded out. It tries to catch for the first few seconds of cranking then looses spark because of the plugs gas fouling. The cylinders fill with gas and push gas out through the spark plug hole. So far I have cleaned the fuel lines, including the return line multiple times, replaced the carb, replaced the fuel pump, changed the oil and filter because of the old fuel pump dumping fuel in the oil, replaced the fuel filters, cleaned the tank, cleaned the points and it now gets a strong spark, and replaced the air filter. It does have electric start setup on it which helps a lot with all the cranking. If anyone has any ideas/advice they would be greatly appreciated.
Thanks


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Re: Mule flooding and won’t start

Post by Grummanflyer » Fri Aug 24, 2018 4:45 pm

The only reason it would flood would be because the float in the carb is stuck open or partially open if you are sure the return line is open. Just because it is a new carb doesn't mean the float can't be stuck. I bought 2 new carburetors and I would not attempt to install either of them without verifying the float was free and the needle is not stuck in the seat. You might have a piece of crap stuck under the needle also but in any case, the float is what controls the level of fuel in the carb bowl and something is keeping it from raising up high enough to stop the bowl from overfilling.

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Re: Mule flooding and won’t start

Post by muleman7 » Fri Aug 24, 2018 5:29 pm

Try running a high percentage of Marvel Mystery Oil in the fuel 16oz to 2 gallons that is 16 to 1. This should go throughout the fuel system and if the engine starts to smoke then you know it has reached the Carb. Once in the Carb you can take a brass hammer and tap on the Carb to see if the needle will loosen and the float/needle should start working properly.

If you have debris holding the needle open then you will need to remove the Carb and disassemble to clear.

The rich MMO will not harm the engine it could oil foul the plugs but once you correct the Carb and add more fuel to the tank the plugs should clear.

Once running I would verify the engine oil level and then set the engine to 2400rpm and let it run for 15 minutes.

CAUTION: check the lube level in the transmission prior to the 2400rpm run-in.

Then set the rpm to 900 and make your final Carb adjustments: Air-Fuel and Idle.

This should resurrect a 20 year sleeping mule engine.

I use
2oz of Sta-Bil per 5gal of non ethanol fuel
Rosella T1 30wt engine oil it meets the Mil-L-2104C standard
Seafoam in my fuel to condition and attract any water
Keep my gas tank full to prevent moisture intrusion
Rislone as an engine oil additive others on G503 use MMO, your choice

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Re: Mule flooding and won’t start

Post by Cbrinker » Sat Aug 25, 2018 4:31 am

Thanks guys, I plan to check the carb and try those things later today when I get over to the shop. I have a lot of that t1 Rotella because that is what we use in our tractors so I will use that as oil. I also have another spare new carb so I can check and install it. Thanks again, I will post an update once I have done all that.

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Re: Mule flooding and won’t start

Post by muleman7 » Sat Aug 25, 2018 5:34 pm

This is how I initially set a New Carb:

1-Uncrew the Knurled Cap on the side of the Carb and pour in about 1/2 cup of MMO. Letting it wet the Accelerator Plunger and Leather Cup and flow into the hole allowing the MMO into the Fuel Bowl. Replace the Cap.

2-Shake the Carb then work the Throttle Lever open and closed until there is no more MMO discharging from the Accelerator Tube located at the front of the Carb Throat.
This wets the Leather Cup and verifies fuel discharge from the Tube.

3-I screw in the Low Speed Screw until the Throttle just opens this will allow the engine to start and idle about 1200 rpms.

4-I screw in clockwise the Air-Fuel Mixture Screw till it closes and back it counterclockwise 3/4 Turn. I find this setting to be about right for final adjustment after the engine is at operating temperature and 900 rpms. final adjustment of the Air-Fuel Mixture Screw is MAX rpm at idle. if too high you may readjust the Idle Screw.

5- Install the throttle linkage onto the Throttle Lever The nut is hard to start onto the screw once the Carb is installed.

Using this procedure I have had no New Carb failures. When I sell a Carb I perform this same process for my customers.
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Re: Mule flooding and won’t start

Post by Cbrinker » Sun Aug 26, 2018 2:47 pm

Thanks, I picked up some MMO today and intend on trying these things as soon as I can

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Re: Mule flooding and won’t start

Post by Cbrinker » Sat Oct 13, 2018 3:42 pm

I finally had a chance to put a new carb on and use that process. The carb seems to be functioning properly now and there is no fuel dumping out the mouth of the carb, but the mule will still not start and is filling the plugs and cylinders with fuel. I have cleaned the return line and the t multiple times, but they were clean. I know that it is getting good spark. I’m at a loss for what it could be

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Re: Mule flooding and won’t start

Post by Grummanflyer » Sat Oct 13, 2018 5:32 pm

There are only a few things that ANY engine needs to run.
1. It needs fuel and it appears you have that covered. Make sure the choke is properly rigged and not in the on position all the time.
2. It needs spark and that seems OK. Some plugs will fire outside the engine but will not fire under compression due to the added resistance of the air/fuel charge.
3. It needs compression. You might try screwing a compression gauge in it and cranking it over to verify you don't have a stuck valve.
4. It needs to be in time. Don't know if the mag has been off or not.

It sounds like you had such a massive amount of fuel that it's wetting the plugs as soon as you crank it. I would pull the plugs and crank it over until it stops blowing fuel out the plug holes and possibly even leave the plugs out so it can dry out in the cylinders or you could try blowing compressed air in the plug holes to help it dry up.

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Re: Mule flooding and won’t start

Post by Cbrinker » Sun Oct 14, 2018 5:15 am

Grummanflyer wrote:
Sat Oct 13, 2018 5:32 pm
There are only a few things that ANY engine needs to run.
1. It needs fuel and it appears you have that covered. Make sure the choke is properly rigged and not in the on position all the time.
2. It needs spark and that seems OK. Some plugs will fire outside the engine but will not fire under compression due to the added resistance of the air/fuel charge.
3. It needs compression. You might try screwing a compression gauge in it and cranking it over to verify you don't have a stuck valve.
4. It needs to be in time. Don't know if the mag has been off or not.

It sounds like you had such a massive amount of fuel that it's wetting the plugs as soon as you crank it. I would pull the plugs and crank it over until it stops blowing fuel out the plug holes and possibly even leave the plugs out so it can dry out in the cylinders or you could try blowing compressed air in the plug holes to help it dry up.

GF
Thanks, I will try to clear out the cylinders and check the compression as soon as I can. I did have the magneto off to clean the points, but i’m pretty sure it is timed correctly because I did have it run for about 30 seconds when I had someone pull me to try to bump start it before it flooded out with the old carb. I’m thinking and hoping that just getting that fuel out of the cylinders and putting in good plugs will allow it to start. It has an electric start setup that was retrofitted with a M151 jeep starter, do you think that it might not be turning over fast enough considering the only time it tried to start was when I tried to bump start it?

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Re: Mule flooding and won’t start

Post by muleman7 » Sun Oct 14, 2018 6:37 am

Most electric starters will spin the engine above the speed that will pull in the stop pawl of the impulse coupler causing it to not impulse. The engine should start easily at the electric start rpm.

When pull starting with the wire rope assy the impulse coupler will engage and you will hear the magneto snapping when it releases. This occurs below 400 rpm and an engine in good shape starts easily if you have fuel, compression and correct timing.

Your engine compression should be 110#-125# with mule heads with the copper head spacer and 130#-145# with genset heads w/o the copper head spacer.

The AO42 mule engine is 6.4 to 1 and the 2AO42 genset engine is 6.9 to 1 compression ratio. As explained to me many years ago by one of the Hupp Hercules engineers on the Mule engine project they dropped the compression ratio to increase lower rpm torque.

Make sure your oil level is correct

As suggested purge all fuel from your cylinders and install new spark plugs I suggest Autolite plugs either the 2224 or 2226 as the 2223 are hard too find and is the plug suggested in the manual. The 2226 is the hotter of the 2. If running your mule for short periods I would run the hotter plug.
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Re: Mule flooding and won’t start

Post by Cbrinker » Sun Oct 14, 2018 11:38 am

muleman7 wrote:
Sun Oct 14, 2018 6:37 am
Most electric starters will spin the engine above the speed that will pull in the stop pawl of the impulse coupler causing it to not impulse. The engine should start easily at the electric start rpm.

When pull starting with the wire rope assy the impulse coupler will engage and you will hear the magneto snapping when it releases. This occurs below 400 rpm and an engine in good shape starts easily if you have fuel, compression and correct timing.

Your engine compression should be 110#-125# with mule heads with the copper head spacer and 130#-145# with genset heads w/o the copper head spacer.

The AO42 mule engine is 6.4 to 1 and the 2AO42 genset engine is 6.9 to 1 compression ratio. As explained to me many years ago by one of the Hupp Hercules engineers on the Mule engine project they dropped the compression ratio to increase lower rpm torque.

Make sure your oil level is correct

As suggested purge all fuel from your cylinders and install new spark plugs I suggest Autolite plugs either the 2224 or 2226 as the 2223 are hard too find and is the plug suggested in the manual. The 2226 is the hotter of the 2. If running your mule for short periods I would run the hotter plug.
I purged the fuel from the cylinders, check the compression (90# on both cylinders which seems pretty low to me), and it started, then I checked all the fluids and took it for a ride. There was so much smoke that I could hardly even see behind me, but it seemed to clear up to a reasonable amount after awhile. Also, while it was running it seemed to be making a lot of clattering noise, but I may just be overly sensitive to it. After running it for about 30 minutes I shut it off to see if it would start back up and it did not. I replaced the plugs which seemed somewhat oil fouled and it still would not even try to start when it was warm or after it cooled down. My mule had been converted to civilian plugs and wires so I have been running the autolite 3116 plug which had the correct heat range and dimensions.

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Re: Mule flooding and won’t start

Post by Grummanflyer » Sun Oct 14, 2018 5:20 pm

Did you check for spark after the engine was hot? Not uncommon for a coil to break down after it gets warm. If you pull the coil out you might be able to see small cracks radiating out from the lamination but the absence of those does not guarantee its good.
Image
This coil was running fine until I turned off the engine and it never made another spark.
John Emery fixed one a while back that would only fail after he heated it up with a heat gun. Muleman has a Mercotronic ignition tester and so do I. Its not a big job to test it. Just because it cooled down does not guarantee it will start again. Your compression test is a little low but then Continental purposely filed the compression ring gaps down on one of their aircraft engines until it only had 40 lbs of compression as tested with a differential compression tester and it still made rated power. The excess smoke is likely fuel and oil accumulated in the muffler and exhaust system and will eventually burn out but you could have stuck or worn rings. That would account for the low compression and possibly the excess smoke but then it could be coming from the MMO if you followed Mulemans suggestions on it's use.
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Re: Mule flooding and won’t start

Post by Cbrinker » Mon Oct 15, 2018 5:01 am

Grummanflyer wrote:
Sun Oct 14, 2018 5:20 pm
Did you check for spark after the engine was hot? Not uncommon for a coil to break down after it gets warm. If you pull the coil out you might be able to see small cracks radiating out from the lamination but the absence of those does not guarantee its good.
Image
This coil was running fine until I turned off the engine and it never made another spark.
John Emery fixed one a while back that would only fail after he heated it up with a heat gun. Muleman has a Mercotronic ignition tester and so do I. Its not a big job to test it. Just because it cooled down does not guarantee it will start again. Your compression test is a little low but then Continental purposely filed the compression ring gaps down on one of their aircraft engines until it only had 40 lbs of compression as tested with a differential compression tester and it still made rated power. The excess smoke is likely fuel and oil accumulated in the muffler and exhaust system and will eventually burn out but you could have stuck or worn rings. That would account for the low compression and possibly the excess smoke but then it could be coming from the MMO if you followed Mulemans suggestions on it's use.
When I had the magneto out I pulled out the coil and looked at it because I had read about the cracking and it seemed fine, but I am going to check the spark again. I did use a high concentration of MMO in the fuel as Muleman suggested so I am thinking and hoping that is what’s causing all the smoke.

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Re: Mule flooding and won’t start

Post by muleman7 » Mon Oct 15, 2018 5:58 am

"Also, while it was running it seemed to be making a lot of clattering noise,"

This may be due to the lifters that leaked down. I use Rislone about a pint added to the engine oil and they will run quiet in about 5-10 minutes.

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Re: Mule flooding and won’t start

Post by Cbrinker » Mon Oct 15, 2018 10:50 am

Ok, thanks. I tried some of that in my ram truck a while back and it seemed to help so that will be on the list for the mule


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