Owners of the 1999 and 2000 model of the Suzuki Hayabusa may face this problem when they were to increase the engine compression (in one way or another); resulting in higher ambient temperature under the fuel tank. Add to that equation a in line fuel filter, it's a very good recipe for vapour locking the fuel system.
According to wikipedia,
Vapor lock (also known as vapour lock) is a problem that mostly affects gasoline-fueled internal combustion engines. It occurs when the liquid fuel changes state from liquid to gas while still in the fuel delivery system. This disrupts the operation of the fuel pump, causing loss of feed pressure to the carburetor or fuel injection system, resulting in transient loss of power or complete stalling. Restarting the engine from this state may be difficult. The fuel can vaporise due to being heated by the engine, by the local climate or due to a lower boiling point at high altitude.
The 99-00 model of the Suzuki Hayabusa utilises the external fuel pump as opposed to the in-tank fuel pump from 01 model onwards. This provides the opportunity for vapor lock to occur. The external fuel pump runs 2 fuel lines, 1 inlet and 1 return line. The inlet is gravity fed and is not pressurized. This allows the fuel to vapourize when the engine compartment temperature rises too much due to heat soak.
The fuel pump when moved to the interior of the tank helps prevent vapor lock, since the entire fuel delivery system is under high pressure and the fuel pump runs cooler than if it is located in the engine compartment. Under high pressure the fuel will be harder to vapourize and thus vapour lock is almost unheard of in K1 models and above.
What are the causes of vapour lock?
A vapor lock is more likely to develop when the vehicle is in traffic because the under-hood temperature tends to rise. A vapor lock can also develop when the engine is stopped while hot and the vehicle is parked for a short period. The fuel in the line near the engine does not move and can thus heat up sufficiently to form a vapor lock. The problem is more likely in hot weather or high altitude in either case.
What are some solutions if you have a vapour lock issue?
- Rerouting of the fuel lines away from heat generating components,
- installation of a fuel cooler or cool can,
- shielding of heat generating components near fuel lines,
- and insulation of fuel lines.
If you have a fuel problem, do check if it is caused by vapour lock. You would want to be caught stuck in traffic with a stalled engine and unable to start due to the vapour lock issue.
