On the other hand, the higher HOV, by decreasing the temperature in the fuel rail line as fuel evaporates, could conceivably decrease the amount of vapor that forms in hot fuel lines and lessen the potential for vapor lock. However, in a 2000 HWD test a comparison of the average temperature increase over ambient in the fuel rails of vehicles running E10 and E0 showed no measurable difference on average for 11 vehicles .
The underlying cause of HWD issues is vapor lock, the presence of vapor in sufficient quantities to block adequate flow of fuel to the engine.
Thus, in places where E10 blends are permitted to have a higher vapor pressure than gasoline fuels, they may be more likely to cause problems with vapor lock under hot weather conditions.
There has been some consideration of the specific location within the fuel system where vapor lock might occur.
To prevent vapor lock, the fuel line is shielded from engine heat to the extent possible, the fuel supply lines are pressurized as practicable, and the vapor pressure in fuels is controlled.
It is not clear at what ratio of fuel vapor pressure to fuel system pressure that vapor lock becomes problematic, but this has typically been addressed as an allowable temperature at which the V/L ratio reaches a certain level.
Thus, this correlation suggests that the primary site for vapor lock is in the fuel rail or injector.
Two, the fact that vapor lock is a real issue that needs to be addressed and resolved.
Our fuel cooler has an internal bypass for fuel return (so a tank return is not needed) and the fuel is cooled by sea water (to alleviate vapor lock problems).
Today, a technician is assigned to go to a chemical injection point to determine its status, Upon arrival, it may be determined that the pump is vapor locked
, the chemical has run dry, or everything is in proper working order.