Ford 4000 dying when warm

[Matt in TN]

I have a 73 Ford 4000 (4140) SU 3-cyl gas. It starts and runs fine, but after running awhile it will suddenly sputter and die, almost acting like it's out of gas. It "feels" hot, just judging from the air coming off the engine, but the radiator stays full of 50/50 mix and the temperature gauge reads normal (starts cold and works its way up into the normal position). If I let it sit and cool completely down again it will start right back up and run fine for awhile.

Is there a possibility of a vapor lock situation on these tractors? The fuel system is on the complete opposite side of the engine as the exhaust, so I don't know how that would be. Any ideas?

 

[jinman]

I would purchase an inexpensive IR thermometer and check the temperature of the carb and fuel lines when the vapor locking begins. That should help you isolate your heat source. I'd bet your fuel is boiling in the float bowl and causing your problem, but the fuel piping might also be a culprit. If you can find where the heat is coming from, you might be able to build a heat shield to keep the carb and fuel lines cooler.

Is the tractor doing this now in Tennessee? If so, it will probably be a huge problem in the summer.

 

[dqdave1]

Wrap fuel lines with tin foil. You may want to have coil tested also. Fuel cap is vented?

 

[jinman]

Wrap fuel lines with tin foil. You may want to have coil tested also. Fuel cap is vented?

Dave, many years ago when I had a sports car, I remember reading about someone who wrapped the fuel lines in insulation to keep vapor locking from happening. He found out that it took longer for vapor lock to occur, but it also took much longer for the lines to cool. He determined that the foil was holding the heat around the lines, especially the heat that would normally be dissipated by airflow. His theory was to use tinfoil or some other means to shield the fuels system from a heat source, but allow airflow that would cool the carbs and fuel supply as much as possible.

When I put triple Weber carburetors on my Datsun 240Z, I built a flat aluminum heat shield under them (like a shelf) to keep the heat from the headers away from them. I never had a problem with vapor locking or fuel boiling.

So, I think your idea might help initially, but it might make the problem more severe once the onset of vapor lock begins. Its worth a try if it can easily be done. Tinfoil is a cheap fix if it helps.

I completely agree with you on checking the coil for a spark when the engine quits. If he can jump a spark to his plugs, then he knows the electrical system is not a suspect. A gas cap vent getting clogged is another very good possibility. Just removing the cap and trying to immediately restart would tell you if that was the problem.

 

[RickB]

Vapor lock is unlikely. Check for good fuel flow, there are several screens in the system. one inside the tank in the shutoff fitting, one in the fuel pump, one in the sediment bowl, and one in the carb inlet fitting. It could easily be a sour ignition coil, as suggested. Check for spark immediately after it quits.

 

[Farmwithjunk]

Do you in fact KNOW it's a fuel (gas) issue? I owned a '73 gas 3000 Ford for 32 years that had a voracious appetite for ignition coils. The description of how it ran (didn't run?) sounds just like what you describe.

 

[Soundguy]

Do you in fact KNOW it's a fuel (gas) issue? I owned a '73 gas 3000 Ford for 32 years that had a voracious appetite for ignition coils. The description of how it ran (didn't run?) sounds just like what you describe.

Ditto what Farm said.

It will be easier to fix if you know what's wrong.

guessing it is out of gass, when in reality it sounds like a spark issue will run you in circles.

The moment it dies, pull the main coil wire and see if you have spark.. if so, is it GOOD spark ( blue / whie and willing to jump 3/8" air gap?

if that pans out, see if you have fuel to the carb. ( those holley carbs can be troublesome.. but usually it's n accelerator pump issue.. and other finickyness.. not just random stalling.

back to electrical... no ballast resistor on the later machines.. they instead have a resistor wire in line with the coil. may have a bypass from the ignition for straight while starting.. then restive when running. ( no telling what's been done since 73 by other owners... )

testing that spark will be the 'key' to solving the issue.. IE.. isolate fuel or spark.. then get down on it..

soundguy

 

[Egon]

Check the fuel tank vent also.

 

[Matt in TN]

Thanks for all the help, guys! I did try pulling the gas cap off and re-starting right away, and it didn't help at all. I SHOULD have checked the basics before posting here though. I started tracing the gas lines to see where they might be picking up heat, and verified the fuel filter was flowing freely.

I figured I'd drain the tank and put new gas in, just to eliminate that variable - when I found that no gas came out the drain in the bottom of the tank. Pulling the petcock showed me that it was completely clogged with rust scale (I just installed a new petcock not quite a year ago, so I was SURE that was not the problem!). Anyway - I hosed the gas tank out as well as I could to clear any more loose rust scale out and cleaned out the petcock and everything works great now.

As an added bonus, while I was fooling around with the old girl I figured out how to knock loose a stuck draft control lever, and for the first time ever I got to play with the draft vs. position setting - what a difference!

Thanks again for the help, and I'll know now to watch out for the coil, too!

 

[dqdave1]

Glad you resolved your problem.And without too much hassle and money is a huge plus.