8N hard starting when warm

[Soundguy]

Generally compression comes UP on a warm engine.. not goes down.

that's whay you want to hear a deisel start cold.. not start after it's been warmed.

She may or may not have some lowered compression.. but if she starts fine cold, she's probably at least 75-80 psi ( out of 90 minimum ).. and that's enough to keep a worker going.. ( a comp and leakdown test sure won't hurt in any case though.. )

soundguy

 

[dqdave1]

Make sure the cap vent is open.

 

[Stimw]

Still sounds like ignition problem, condenser or coil. Could even be points gap. Points can act up when hot.
I owned a 8-N and 9-N and other equipment with updraft carbs and they all needed to be close to flooded to start. Updrafts are a different bird altogether.

 

[Clelle]

It did seem to start easier if I shut the fuel off before I kill the motor, then leave the throttle lever down at idle and it would fire easier. If I left the gas on and shut it down then it would be a pain to get back going. As for the spark when I tested it warm and when it tested it cold both times I got a bright blue spark. I will try and get the compression tested here soon just have to find the tester,I know it is around the shop somewhere. , so I think that the carb needs a rebuild because to me it looks pretty original and old. The motor itself has pretty good oil pressure as well so I do not think it is what it in bad shape. It shows 35 cold and 25ish warmed up.

 

[Soundguy]

Still sounds like ignition problem, condenser or coil. Could even be points gap. Points can act up when hot.
I owned a 8-N and 9-N and other equipment with updraft carbs and they all needed to be close to flooded to start. Updrafts are a different bird altogether.

If he has spark at stall.. it ain't the electrics.

points not working when hot? that's a queer problem.. they should either be open or shorted.. usuaully the only thing that could happen is the nylon insulator at the hinge.. but when it goes.. it usually don't 'heal' when it cools.

soundguy

 

[carpenter383]

That's funny!..and wrong...

A shutoff inline to keep it from flooding when running is a pretty BAD piece of advice. You'd constantly have to reach down there and open the valve to let the carb bowl refill every minute or so.. !DOH! ( slapping head sound )

The needle / seat simply need to be cleaned or R&R if they are not sealing and allowing her to run over... that or adjust the floa height.. or make sure it is not heavy.. etc.

besides there is ALREADY a cutoff valve inline with the carb up at the tank.. don't help much for the flooding does it?

soundguy

You should read the whole response before you bash it. Maybe I wasn't clear enough, I was saying the feul shut off could be used for AFTER you shut the tractor off. This will keep the fuel level from continuing to rise and causing it to flood after he shuts the tractor down. (Which is what it sounds like is happening) I didn't know it already had one on the tank.

 

[Egon]

I will try and get the compression tested here soon just have to find the tester,I know it is around the shop somewhere

Back when the crank out front worked quite well for that purpose!

Maybe the next you get running and warmed up set it to half throttle and make small adjustments to the needle valve listening to how the engine sounds. Pick a spot that sounds right and try that.

 

[Eagleview]

I am not familiar with these tractors . Do they have a fuel pump or are they gravity fed ? Do they have a Bakerlite spacer on the carb flange to stop fuel boiling ? I have fixed cars with Chrysler "hot start" kits . They are just a plastic in line fuel filter with a return line barb on the carb side . The barb has a pin prick size hole in it . A small hose goes back to the inlet side of the pump . When the motor is turned off hot , the excess line pressure returns to tank instead of pushing past the needle and seat while the float is being jostled by the boiling fuel in the float bowl and then flooding the engine . Most auto stores will have them (only helps if it has a pump) .

 

[Egon]

Forgot to mention, drain some of that yellow gunk out of the carb float bowl.

 

[J_J]

Maybe this data will help some.

Ford 8N Tractor Carb Adjustments

Ford 8N Tractor Fel System

 

[Soundguy]

I am not familiar with these tractors . Do they have a fuel pump or are they gravity fed ? Do they have a Bakerlite spacer on the carb flange to stop fuel boiling ? I have fixed cars with Chrysler "hot start" kits . They are just a plastic in line fuel filter with a return line barb on the carb side . The barb has a pin prick size hole in it . A small hose goes back to the inlet side of the pump . When the motor is turned off hot , the excess line pressure returns to tank instead of pushing past the needle and seat while the float is being jostled by the boiling fuel in the float bowl and then flooding the engine . Most auto stores will have them (only helps if it has a pump) .

No fuel pump on the ag engines. though some industrials, and later models did.

soundguy

 

[Soundguy]

Maybe I wasn't clear enough, I was saying the feul shut off could be used for AFTER you shut the tractor off. This will keep the fuel level from continuing to rise and causing it to flood after he shuts the tractor down. (Which is what it sounds like is happening) .

I'll go with that... had you actually posted that.. the reply would have been different.

I didn't know it already had one on the tank.

That's why random guesses help less then organized diagnostics.

A flood condition from a bad needle / seat is uite easy to diagnose at shutoff by pulling the air line and observing the mouth of the carb, and the sinterizeded plug.

soundguy

 

[wolc123]

I am interested in how this one turns out. I dont have this problem with my 8n Ford, but my 1941 Allis Chalmers C does exactly the same thing. If you stall her after or during a real hard, hot workout, there is no way she will start again sooner than an hour or so. I had a real whiz rebuild the carb recently so I am quite certain that aint the problem. When she quits on me like that, I just leave her parked in the field and take a break or go get another tractor if the job has to get done fast. The problem can be especially aggrivateing and tireing because this tractor does not have electric start (must be cranked over by hand). This is a very tempermental tractor and also does not start good when the temperature is colder than 50 F or so.

 

[Egon]

Did you try holding the throttle wide open while cranking as I mentioned before? If it is flooding from the needle and seat not holding the fuel back

you could put a shut off valve in the line for a temporary fix.

Strangely enough I was able to understand what Carpenter383 was saying here.

 

[Clelle]

Well I bought and installed the factory steel fuel line and cleaned the carb out a bit with it still on the tractor. I also re adjusted everything on it and got the idle down pretty low so I could adjust the idle mixture screw. After a bit of tuning on the carb it seems to be running great, took it out and got it hot over the weekend and killed it, and turned it over twice and it fired right up. So thanks to everyone for the input on the subject, I guess the ol carb just needed a little lovin to bring her back to life.