vapor lock

Eagle_1 · Aug 17, 2011

I have a 1964 Ford 4000, that I have had for more than 20 years. I normally only run the tractor for an hour or so at the time and have no problems. When I have a problem it is usually after I have run the tractor hard for 4 or 5 hours, it just stops on me. Acts like it has run out of gas but it hasn"t. This happens to me once or twice a year and has for the 20+ years I"ve owned it. After the tractor sits for an hour or so it"s ready to go again. Over the years I have made several changes to the tractor, 12 volt -gnd, electronic ignition, replaced wiring harness, carb kit.

It"s hard to troubleshoot something that fixes itself.

I have been wondering if I might be experiencing vapor lock? Was wondering if anyone might enlighten me with the symptoms and cause. And some suggestions on how to prevent it?

Dean · Aug 17, 2011

It's not vapor lock.

By definition, a gravity flow fuel system cannot vapor lock.

Have you changed the ignition switch?

Dean

JMOR · Aug 17, 2011

(quoted from post at 18:35:33 08/17/11) I have a 1964 Ford 4000, that I have had for more than 20 years. I normally only run the tractor for an hour or so at the time and have no problems. When I have a problem it is usually after I have run the tractor hard for 4 or 5 hours, it just stops on me. Acts like it has run out of gas but it hasn"t. This happens to me once or twice a year and has for the 20+ years I"ve owned it. After the tractor sits for an hour or so it"s ready to go again. Over the years I have made several changes to the tractor, 12 volt -gnd, electronic ignition, replaced wiring harness, carb kit.

It"s hard to troubleshoot something that fixes itself.

I have been wondering if I might be experiencing vapor lock? Was wondering if anyone might enlighten me with the symptoms and cause. And some suggestions on how to prevent it?

To quote Dean's correct statement, "By definition, a gravity flow fuel system cannot vapor lock. " Have you verified that tank is vented?

Geo-TH,In · Aug 17, 2011

I added an in-line fuel filter to a gravity flow system. It would vapor locked on 95+ degree days.

Did you add an in-line after market fuel filter?

Eagle_1 · Aug 17, 2011

I put the ignition switch in new over 20 years back when I first rebuilt the tractor. Have not touched it since.

Keith Williams · Aug 17, 2011

Eagle 1,
I too have a 64 Ford 4000. My rad was getting plugged up some and it was getting hot on a hot day. I got off and looked at the sediment bowl. I could acually see bubbles in the bowl. Mine just kept on running. Next time it quits you need to check to see if giving it a little choke does anything. Check the Sediment bowl for gas, and check for spark.
By the time the 4000 series was made, Ford had made some improvements, one of those was a larger fuel line. If yours is original I would bet it is something other than vapor lock.
IF there is no fuel in the bowl, is your tank clean, could your line be plugged at the bottom of the tank?
Did you use a Ballast resistor or did you use a "12 volt" coil marked no external resistance needed? Coil could be getting too hot.
The ignition switch could be the problem, does it crank when it stops? The 4000 had the selinoid powered through the switch. You still have the 4 post one correct.
I ran my 4000 for 5 or 6 hours today. Ran almost a full tank of gas through it. Never gave me any problems. Yours has to be something that is just a little out of wack.
Good luck!
Keith

Eagle_1 · Aug 17, 2011

It just starts surging and lurching until it shuts down. Working the throttle and choke has negative results
Engine temp is in the green, does not run hot. There are no bubbles in the sedimnent bowl, the bowl is full of gas.
I have a resistor but this is for exciting the alternator.
Coil is one year old.
Tank is clean, fuel line is 2 years old and I just changed the fuel shutoff valve last week.
The last 2 times it happened I did get it to crank back up but previous to this I had to wait at least an hour to get it to crank.
Spark seems to be good, but every time this happens I am back in the woods somewhere, away from my tools and test eq..

souNdguy · Aug 18, 2011

you can jumper around it to test.

also.. at moment of death.. is there spark? at the coil wire to block...is there fuel in the carb bowl?

post back

soundguy

Dave in MS · Aug 18, 2011

Get a new gas cap. I'll bet your vent is plugged.

Keith Williams · Aug 19, 2011

Eagle-1,
Sounds more like an electrical problem. 2 problem areas are the coil and the switch.
I really feel for you as this is a very intermittant problem.
Did you look at the coil to see if it has any markings on it? If it says external resistance needed, and you have no ballast resistor, your coil would be overheating and then cutting out. When it cooled off you would be running again.
The key switches seam to also be a problem area. They heat up and then cut out only to start working again after they cool.
Both would do just as you stated.
Look at the coil. You can also measure it's resistance.
When you said that it would not even crank when it shut off. That could well point to the switch.
Just trying to help.
Keith

Eagle_1 · Aug 19, 2011

Tractor has been doing this to me for 20 years, about once a year. Seems I am always a long way from my tools or test eq when it happens. Spark seemed to be OK.

In years past it would not restart for about an hour. This year it has happened twice, both of these time I got it restarted but it ran very badly. It would idle smoothly but lurched and surged badly at RPMs above idle. One of these times I had to drive the tractor about a mile, this made for a very rough drive out of the woods, was afraid I was going to tear something else up. Played with the throttle constantly trying to keep it running.

Talked to the Hew Holland dealer today and he is getting me a vented fuel cap, I still had the original. If this doesn't solve things the next thing I'm going to try will be an ignition switch. Guess I could try jumping the switch but the truth is this only happens after I have run the tractor very hard for 4 or 5 hrs, making it difficult to work under the hood, usually I'm about as hot and tired as the tractor.

souNdguy · Aug 20, 2011

to test the cap issue.. leave it loose.

I always break down or run out of gas the farthest away from fuel. I think I am gonna make a bracket on my mower to hold a 1g gas can and tool box..

soundguy

vapor lock

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Dean

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