vapor lock explained
The fix for high fuel flow low pressure would be to replace the pump like we did.
I agree with you. Like I said in my previous post, higher fuel pressure and lower temperatures help to prevent vapor lock. The new pump puts out more pressure to help prevent vapor lock. The word LOCK is a misnomer. The fuel is not locked or blocked. Actually in a vapor lock situation, the fuel actually flows faster and the pressure drops. The reason for this is that the fuel forms little vapor bubbles in the fuel line. Since a mixture of fuel vapor and liquid flows easier than pure liquid, the flow increases. In addition, the fuel vapor escapes out of the carburetor vents, which also increases the flow. Also, the mixture of fuel vapor and liquid can more easily flow through the return line orifice back to the tank. The pressure drops because there is less resistance to flow. An analogy is a garden hose. If allowed to flow freely, the flow rate is high but the pressure is low. But hold your thumb over the end of the hose to restrict flow and the pressure goes up, causing the water to squirt further.
When the engine demands more fuel at full throttle, it can be starved if part of the fuel is escaping out of the carburetor vents as vapor.
I can think of 3 ways to prevent vapor lock:
1. Use a fuel that is less prone to vapor lock. (Fuels containing alcohol or winter additives evaporate easier.)
2. Increase the fuel pressure by using a better pump (like RDOG did).
3. Keep the fuel system cool with insulation or shrouds or cooling air.
With fuel constantly flowing through the lines back to the tank where would the vapor lock occur?
Fuel constantly circulating back to the tank helps to keep the fuel cool. However fuel obeys the laws of physics. It will evaporate if the conditions are right, depending on the properties of the fuel, the temperature and pressure.
Joe Gores