My '55 IL6 just stopped yesterday in traffic. It sputtered like it just ran out of gas. After a tow home, I've checked and cleared my lines with air, replaced the fuel filter, primed it and even sucked fuel from the carbuator to get fuel in the filter. Any thoughts? How can I test the pump? it's an aftermarket mechanical. Thanks.

 

Inline fuel pressure gauge would show pump function. Could just be a stuck float or trash in the carb.
Just got my massey 135 tractor out for the first time in a couple years, did the same thing (but not in traffic ). Had to finish brush hogging by tapping on the carb bowl ever few minutes or so! Time to drop the bowl and clean out the carb.

 

Thanks for the leads! We'll get this figured out.

 

If the ambient temperature was very hot, you may have had vapor lock. You do not indicate if the truck started when cooled off or if you have it running. Below is a basic fuel system troubleshooting guide. The guide is general, you may find slight differences for any specific application.
Edit: Hot electrical components could cause the same problem. Coils are noted for this type problem. Troubleshooting is in order. If it happens again, try to determine that you have spark. Sometimes a close observation will point to the problem or help us help you determine where the problem is. Many times a fuel problem will be indicated as the engine stumbling, missing before quitting entirely.

TESTING THE FUEL PUMP

Fuel pumps should always be tested on the truck. The larger line between the pump and tank is the suction side of the system and the smaller line, between the pump and carburetor is the pressure side. A leak in the pressure side would be apparent because of dripping fuel. A leak in the suction side is usually only apparent because of a reduced volume of fuel delivered to the pressure side.


Tighten any loose line connections and look for any kinks or restrictions.

Disconnect the fuel line at the carburetor. Disconnect the distributor-to-coil primary wire. Place a container at the end of the fuel line and crank the engine a few revolutions.

If little or no fuel flows from the line, either the fuel pump is inoperative or the line is plugged. Blow through the lines with compressed air and try the test again. Reconnect the line.

If fuel flows in good volume, check the fuel pump pressure to be sure.

Attach a pressure gauge to pressure side of the fuel line. On trucks equipped with a vapor return system, squeeze off the return hose.

Run the engine at idle and note the reading on the gauge. Stop the engine and compare the reading with the following:


6-cylinder inline engines.....4.5 to 6 psi.
V8 engines.....5 to 9 psi.


If the pump is operating properly, the pressure will be as specified and will be constant at idle speed. If pressure varies sporadically or is too high or low, the pump should be replaced.

Remove the pressure gauge.

The following flow test can also be performed.

Disconnect fuel line from carburetor. Run fuel line into a suitable measuring container.

Run the engine at idle until there is one pint of fuel in the container. One pint should be pumped in 30 seconds or less.

If flow is below minimum, check for a restriction in the line.

 

We should create a twisty at the top for this problem based on the number of times that it is asked. Here are a couple other ideas to add to Ray's fuel pump suggestions:

1. Dirt in fuel tank
2. Clogged fuel filter (I know that you said that you replaced that already but if there is dirt in the tank it will get clogged again).
3. Dirt in the carb
4. Overheated coil and/or condenser
5. Non-vented gas cap installed when it should be a vented cap
6. Vapor lock (fuel line overheating - old timers trick test is to add clothes pins to the line)

These are just a few of the more common issues. Good luck. Let us know what you find.

 

Thanks for your help, guys! Following some of your ideas, the diagnosis focused on the fuel pump, although I know my tank is cruddy!
I thought I could just buy a pump based upon the engine year and model. No. The metal tag on the pump has the model number embossed. Long story, but I bought the wrong pump, installed it and learned the hard way.
Thanks again!

On the road again!