The most important step for maintaining a fuel system is to keep it clean and free from water. The system should be periodically inspected for leaks. In this segment of Willys Jeep Parts the fuel pump will be covered from the proper operation of the fuel pump to its removal and important questions that are asked.
The correct fuel pump pressure is essential to satisfactory engine performance. Pressure that is too low will affect proper carburetion. Pressure that is too high will cause fuel leakage at the carburetor intake valve. This is the checklist for a single action fuel pump.
- To check fuel pump pressure, connect a pressure gauge into the fuel line at the carburetor with a T-fitting. At 1800 rpm. engine speed, the pressure should not exceed 4.75 psi.
- For a test of volume, the pump should prime itself in 18 seconds at 120 rpm. engine speed.
- For a test of vacuum, the pump should pull 10.25″ of mercury at 1800 rpm. engine speed.
- Volume Check: To measure the fuel pump capacity (the amount of fuel delivered in a given time) disconnect the pump to carburetor line at the carburetor end. Place the open end of the line in a container suitable for the amount of liquids delivered. Start the engine and operate at normal idle speed. The volume should be one quart U.S. or 1 liter within one minute.
- Pressure Check: To measure fuel pump pressure (force of fuel delivery) disconnect the pump to carburetor line at the carburetor end. Insert a pressure gauge and T-fitting into the open end of this line and into the carburetor. Engage the engine and operate at normal idle speed. Pressure should be 2.5 to 3.75 psi. at 1800 rpm. and at 16″ above the outlet.
- Vacuum Check: To measure the fuel pump vacuum (the pull of the pump at the inlet side) disconnect the pump to fuel tank line at the fuel pump. Connect a vacuum gauge to the fuel pump inlet. Start the engine, accelerate to specified speed, and hold this engine speed while taking a gauge reading. Correct gauge reading is 8″ (203 mm.) of mercury at 1200 rpm. and 10.5″ (267 mm.) at 1800 rpm.
- Vacuum Booster Check: To test the condition of the vacuum booster pump, disconnect both inlet and outlet lines at the pump. Attach a vacuum gauge to the windshield wiper connection at the pump. Start the engine, accelerate to 2000 rpm., and hold this engine speed while taking a gauge reading. Correct gauge reading is 10″ (254 a 356 cm.) of mercury.
In addition to the previous tests mentioned the following can also be checked.
- Check for secure mounting of the fuel pump. The rocker arm may be working the entire pump up and down, rather than just the pump diaphragms.
- Remove and clean the fuel sediment bowl.
- Check all fuel lines.
How to remove fuel components from your Willys Jeep – Part of an ongoing “Jeep” disassembly and restoration series sponsored by Kaiser Willys.
To watch other videos on the disassembly of your Willys Jeep Vehicle refer to The Build Your Willys series on YouTube. Order the Service Manual For The Universal Jeep Vehicles, includes complete vehicle disassembly, assembly, and blowup diagrams.
New Replacement Fuel Pump (single action) For 41-71 Jeep & Willys with 4-134 engine
Call Mike @Kaiserwillys.com for details at TOLL FREE 1-888-648-4923 (Mon-Fri, 9AM-5PM EST).
New Single Action Fuel Pump – Part#: 119238
Q: I bought the fuel pump #119238 for my 1945 GPW. I installed it and the jeep started right up with a little priming to the carb. The question I have is as the vehicle runs the gas in the bowl doesn’t get much more then just off the bottom of the bowl and over the screen. How high is the gas suppose to get in this bowl? It seems to be running right at a stand still in the garage but before I take it out I just wanted to be sure it’s correct and I won’t break down.
- A: It doesn’t fill up all the way typically. The bowl will fill up a little more or less depending on speed/pressure. Sounds like your good to go.
Q: I just got my new fuel pump in! What a beautiful thing it is… glass bowl and all… I just have one question. Does the cam need to be in any particular position prior to me installing? The reason I ask is the other one was working perfectly, until I pulled it out to be able to get to the lines. And when I put it back.. no fuel pump love…. I’m glad I have the new one, now the entire system is new up to the carb…
- A: Just make sure to install this glass bowl pointing up and when you install it make sure the lobe is below the fuel pump arm. Angle it in.
Q: Upon starting my CJ-2A it takes a long time for gas to reach the engine after sitting for an extended period. I think gas must be draining back from the carb over time. It is not leaking externally. Will this new fuel pump cure the problem?
- A: It should help. When you start your vehicle pump the pedal a few times prior to get the fuel going and prime it.
*EMAIL or call Mike Toll Free (1-888-648-4923) Mon-Fri, 9am-5pm EST if you have any questions about this part or restoring your Willys.