Frequently Asked Questions: Fuel System

Parts and Services for the Universal Atomic 4 Engine
Parts: Phone: 717.625.3891 | 410.810.8921 | 717.625.1587 (fax)
Technical Service: Phone: 410.810.8920 | 410.810.8922 (fax)

FAQ: Fuel System

1. Our engine starts and runs fine for about an hour. Then suddenly stops. It can be re-started immediatly and runs fine for another hour or so. The only thing we have done mechanically is add an electric fuel pump.

2. There is a tube going from the intake manifold to the bottom of the carb...what is its function?

3. On my atomic 4 motor starts up ok, but then dies. Does this indicate water in the gas? What would you recommend?

4. Is it OK to mix other additives to the fuel (like stabilizers and moisture inhibitors)?

5. My fuel tank is higher than my engine. Do I need an anti-siphon valve? There is a small round valve installed just above the tank where the fuel line leaves the tank. Could this be some sort of anti-siphon valve?

6. What are the indications of a lean fuel mixture, and how does one correct it?

7. Why does it seem that adjustable main jets are more susceptible to becoming partially blocked than the fixed main jets of later model carburetors?

8. What are the pros and cons of removing the fixed main jet found in late model carburetors and installing an adjustable main jet?

9. Why does dirt get trapped in the float valves of carburetors, rather than move on through as the floats raise and lower the needle against the seat?

10. What is the proper float setting for Atomic 4 carburetors (early and late model)?

11. What is a good initial setting for the idle mixture and the adjustable main jet?

12. I notice that while running the engine rpms change without my doing anything to the throttle. Sometimes it runs faster and some it slows down. Any suggestions as to what could cause this?

13. Can the A-4 use unleaded regular gas, or should a lead substitute additive be used with the unleaded gas?

14. Octane ratings

15. I installed a new oil pressure safety switch and fuel pump, and I'm not sure if I wired it up correctly! Should the fuel pump be running before the engine is actually being cranked, as mine does?

16. Starting fluid

17. What would cause fuel to drip out of the mouth of my carburetor?

18. Fuel pump pressure

19. Recommended additives for gas and oil

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: 1. Our engine starts and runs fine for about an hour. Then suddenly stops. It can be re-started immediatly and runs fine for another hour or so. The only thing we have done mechanically is add an electric fuel pump.; 2. There is a tube going from the intake manifold to the bottom of the carb...what is its function?; 3. On my atomic 4 motor starts up ok, but then dies. Does this indicate water in the gas? What would you recommend?; 4. Is it OK to mix other additives to the fuel (like stabilizers and moisture inhibitors)?; 5. My fuel tank is higher than my engine. Do I need an anti-siphon valve? There is a small round valve installed just above the tank where the fuel line leaves the tank. Could this be some sort of anti-siphon valve?; 6. What are the indications of a lean fuel mixture, and how does one correct it?; 7. Why does it seem that adjustable main jets are more susceptible to becoming partially blocked than the fixed main jets of later model carburetors?; 8. What are the pros and cons of removing the fixed main jet found in late model carburetors and installing an adjustable main jet?; 9. Why does dirt get trapped in the float valves of carburetors, rather than move on through as the floats raise and lower the needle against the seat?; 10. What is the proper float setting for Atomic 4 carburetors (early and late model)?; 11. What is a good initial setting for the idle mixture and the adjustable main jet?; 12. I notice that while running the engine rpms change without my doing anything to the throttle. Sometimes it runs faster and some it slows down. Any suggestions as to what could cause this?; 13. Can the A-4 use unleaded regular gas, or should a lead substitute additive be used with the unleaded gas?; 14. Octane ratings; 15. I installed a new oil pressure safety switch and fuel pump, and I'm not sure if I wired it up correctly! Should the fuel pump be running before the engine is actually being cranked, as mine does?; 16. Starting fluid; 17. What would cause fuel to drip out of the mouth of my carburetor?; 18. Fuel pump pressure; 19. Recommended additives for gas and oil

[e-Mail the FAQ's] - [Search our FAQ's] - [Question Not Answered?]