8N hard starting when warm

Soundguy · Apr 23, 2009

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 · Apr 23, 2009

Make sure the cap vent is open.

Stimw · Apr 23, 2009

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 · Apr 23, 2009

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 · Apr 23, 2009

Stimw said:
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 · Apr 23, 2009

Soundguy said:
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 · Apr 23, 2009

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 · Apr 23, 2009

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) .