Tough starting when hot

Rich in N. Minn · May 27, 2017

Hi Everyone:

I have been a very satisfied member of this board for 10+ years and you guys have helped me out with my 8n and 2n tractors - especially you Dell.

Here is my question: 2n starts great, runs great and is a great tractor on my 5 foot woods finish mower. My mowing job is about 4 hours and if I stop for a 2 minute break after about 2 hours of easy mowing, it will not start. Turns over great but will not fire. If I give it a pull, it starts right up and finishes my mowing job with no problem. This is the original 6 volt system. I don't think it is the coil because once started after sitting a couple minutes, it runs perfectly. I suspected vapor lock but vented the gas cap and that did not fix the problem.

Any suggestions? Thanks

Rich in N. Minn

Dell (WA) · May 27, 2017

Rich.......awe yes, the 2-min peeeee brake. Gitta L O N G E R hoze, ...or... BIGGER BLADDER, eh! Just stand on yer running boards and whizz away. Simple, eh? Nobody is watching.......whizzer Dell shuld'o seen me and my dog competing down the 300-ft lane, every ten-ft gotta shrub. I gotta rotor-rooter job but my dog could lift his leg.

Bruce(VA) · May 28, 2017

No, it's not vapor lock. You don't have a fuel pump. It might be vacuum lock, but that usually occurs w/ in minutes of start up. Boiling ethanol in the fuel is possible, but you would hear that. Besides, does it ever get that hot in MN?

Your symptoms sound like a textbook case of low compression: will only start w/ a pull when hot.

You can increase compression sufficiently by pulling it to start for two reasons. First, it's cranking faster which creates more compression & secondly all of the battery current is going to the ignition & not the starter. Sometimes you get the same result by jumping it w/ a 12v battery. (see tip # 43 for the safe way to do that)

A compression test is easy to do & will answer a number of questions about your problem.

Check out tip # 46. If your gauge has a fitting that screws into the spark plug hole & the hose from the gauge screws into the fitting, do yourself a favor & get a brass elbow at the hardware store. Screw the fitting from the compression gauge into the head, the brass elbow into that, & the gauge into the elbow. Makes it easier to fit under the gas tank. (hint: take the gauge & fitting w/ you to the hardware store!)

Minimum acceptable pressure is 90 lbs w/ the lowest pressure reading w/in 75% of the highest reading. Run the engine to operating temp, turn it off, remove all 4 plugs, remove the breather hose & make sure the choke and throttle are both open. Crank it at least 5 compression strokes or until the gauge stops moving. Write down the first compression reading (that is the valves seating) then write down the reading after 5 strokes or when it stops increasing. You should have two numbers for each cylinder. Then, add a tablespoon of oil to each cylinder & repeat the process, but you only need the final reading for each cylinder. Write down the results & post back for help figuring out what it all means.
75 Tips

Roger in Iowa · May 28, 2017

For 2 minutes or even 10 just let it idle. It is HOT and it needs a break too!

Dean · May 28, 2017

It's not vapor lock.

Most likely low compression.

Dean

Rich in N. Minn · May 28, 2017

Thanks for the advice. My oil pressure is acceptable when running - 30 lbs. I think I will take Dell's advice and stand on the running board. Dell, I read your response to a house full of overnight guests this morning and it made our morning. The best laugh I have had in some time.

Best wishes for a memorable memorial day.

Rich

Hobo,NC · May 28, 2017

(quoted from post at 17:32:58 05/28/17) No, it's not vapor lock. You don't have a fuel pump. It might be vacuum lock, but that usually occurs w/ in minutes of start up. Boiling ethanol in the fuel is possible, but you would hear that. Besides, does it ever get that hot in MN?

Your symptoms sound like a textbook case of low compression: will only start w/ a pull when hot.

You can increase compression sufficiently by pulling it to start for two reasons. First, it's cranking faster which creates more compression & secondly all of the battery current is going to the ignition & not the starter. Sometimes you get the same result by jumping it w/ a 12v battery. (see tip # 43 for the safe way to do that)

A compression test is easy to do & will answer a number of questions about your problem.

Check out tip # 46. If your gauge has a fitting that screws into the spark plug hole & the hose from the gauge screws into the fitting, do yourself a favor & get a brass elbow at the hardware store. Screw the fitting from the compression gauge into the head, the brass elbow into that, & the gauge into the elbow. Makes it easier to fit under the gas tank. (hint: take the gauge & fitting w/ you to the hardware store!)

Minimum acceptable pressure is 90 lbs w/ the lowest pressure reading w/in 75% of the highest reading. Run the engine to operating temp, turn it off, remove all 4 plugs, remove the breather hose & make sure the choke and throttle are both open. Crank it at least 5 compression strokes or until the gauge stops moving. Write down the first compression reading (that is the valves seating) then write down the reading after 5 strokes or when it stops increasing. You should have two numbers for each cylinder. Then, add a tablespoon of oil to each cylinder & repeat the process, but you only need the final reading for each cylinder. Write down the results & post back for help figuring out what it all means.
75 Tips

I believer its inertia that will get a low compression engine running on its own, I don't see were pulling it off will increase compression. So, you give a nice brief suggestion to check basics but the poster is too lazy to follow up on them he would rater go the EZ route...

Duner Wi · May 28, 2017

Try by passing the resistor on backside of dash just while starting it.

Rich in N. Minn · Jul 19, 2017

Hi Everyone:
Just an update on my tough starting when hot. It was the coil. I have replaced coils many times and this one was different because the problem did not occur until after the tractor had been running a couple of hours. Prior coil issues occurred after 30 minutes of running. The replacement coil is made in China so we will see how long that lasts. Thanks everyone for your input and Dell - Thanks for the laughs.

Rich

Royse · Jul 19, 2017

Thanks for the follow up post Rich. Many forget to do that.
Still seems odd for a coil problem, but "fixed is fixed, whether
it's duct tap or zip-ties" as Red Green would say!
Glad you got it working again.

Tough starting when hot

Rich in N. Minn

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Dell (WA)

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