Do you have a bleed circuit between your pump and fuel pressure

regulator? Do you have heat shields on your fuel lines? My guess is that

you may have experienced vapor lock.  Without a bleed circuit, the fuel

pump can't produce enough pressure to overcome the fuel pressure

regulator

 

This should only be an issue if the pump is not located at the lowest point in the line from the tank.  As long as there is liquid at the pump inlet – no problem.

 

Al

 

Al,

What happens if the lines in the engine bay and fuel pumps get hot enough for the fuel to boil inside them?  Are the pumps still going to produce enough pressure to function normally?  My guess is no.   Paul said his coolant temp was 210+.  He had been doing extended ground runs followed by some taxiing, which would allow for lots of heat soak and little cooling air.  I imagine the fuel pumps and lines were pretty warm.  Maybe warm enough to cause vapor lock.      

 

I would also like to know what type of fuel he was using at the time?  If he was running mogas, has he checked the vapor pressure of the fuel? 

 

Paul, do you have a return on your fuel system?  If so, where does it return to?  What size lines?          

 

Mark S.