A fuel geyser occurred during helispot construction operations on Div T of the June fire on 23-Jul-17. Saw operations began at approx 1100 on an exposed ridge at 6600' elevation. After running the first tank without incident, the tank was refueled and the saw team sat down for lunch at approx. 1200. The lunchspot was fully exposed to the sun and the temperature was 78-80 degrees F. Saw fuel was being stored in MSR cig bottles, within a blue carry bag. After a 30 minute lunch break, and upon re-start to begin the second tank, the saw would rev high, then bog down when the throttle was applied. If the throttle was continually applied, the saw would die completely. If the throttle was released and feathered, the saw would rev high again. After going through this cycle for 2-3 mins, boiling gas was suspected. The saw team let the saw sit for a minute or two. The saw operator placed the saw on the ground, turned the fuel tank away from their body and vented the cap. The cap was turned about 1/8 of a turn and fuel geysered from the partially open cap (away from any persons and into the ground). After geyser incident, remaining fuel continued to boil inside the tank. The saw team let the saw sit for another 2-3 minutes with the gas cap off. The saw and operators were still fully exposed to the sun. After the boil diminished, the fuel cap was closed and the saw was restarted. The saw revved, bogged a few times and sounded lean. Upon applying full throttle, the saw team cut into a log and heard the saw richen up and normalize. After that, saw operations continued as normal. Additional fuel was placed in the shade. When the saw was refueled, the saw team kept the fuel level at 1/2 to 3/4 of a full tank, with no issues. At 1600, the saw team dropped a few hundred feet during a 10 minute down hike. After an additional 10 minute break, the saw was turned away from all persons, and the fuel cap was vented again. Another geyser occurred. Cooling process was repeated and saw operation continued as normal. Fuel tank was 3/4 full, and the temp had increased to 86-88 degrees F. |