Fuel Shut Off?

Johnny007 · Aug 3, 2015

My 48 8N will run for about an hour and then it will die, almost like its run out of gas (but I have flow at the carb). If I let it cool down (a couple hours) it will start back up. I did notice that when the engine is cool, the fuel shut off is easy to turn open, but when she's hot, it turns a LOT harder. I'm wondering if I have a vapor lock or something going on when things get hot. Ideas? Fixes? Thanks for your time!

Dean · Aug 3, 2015

By definition a gravity flow fuel system cannot vapor lock.

You may be experiencing the vintage Ford ignition switch problem, which is difficult to diagnose and not something that I will attempt to coach in a chat forum.

The next time you plan to use your tractor for an extended period of time, short out the ignition switch with a jumper wire. If the problem goes away, replace the ignition switch.

Dean

Johnny007 · Aug 3, 2015

Dean thanks for your reply. When you say short out my ignition switch, do you mean jump a wire across the back of the switch? Engine on? I'm a geologist, not an electrician, so please forgive my very basic comprehension of this stuff. Thanks! I have replaced the switch once this season...

notjustair · Aug 3, 2015

Yes, that's where he's going with that. Do you have a short piece of wire with alligator clips on it? Just clip the two together and give her a try.

Dean · Aug 3, 2015

Yes.

The replacement ignition switches are a known source of temperature-related high resistance connection.

Connect the contacts together to effectively remove the switch from the primary circuit.

Dean

ratface · Aug 3, 2015

For clarity I think you guys are telling him to jump the push button switch on the tranny cover and not the on/off switch or key switch so he knows where to go. If so there is no back part to the switch and you jump from the screw with the wire attached to the tractor body.

old · Aug 3, 2015

Note Dean says ignition switch not starter switch or button

grapeview8n · Aug 3, 2015

Being a '48 I'll assume it's a front mount distributor. Sounds like ignition coil to me. As soon as it dies, check spark. If no spark, coil or condenser.

dactura · Aug 3, 2015

Yes... previous discussions about the coil working fine at cool temps and then crapping out when they get hot.

Johnny007 · Aug 4, 2015

Grape that's a good call, had similar issues with my 73 BMW. If jumping the starter switch doesn't work, I will look at the coil next. thanks for the advice!

Johnny007 · Aug 7, 2015

Hey now,

so jumping the ignition switch did not help, but when I checked for spark, I had none, so I will be trading out the coil and HOPEFULLY that will be the end of it. Always learning!

Fuel Shut Off?

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