A malfunctioning fuel transfer pump can cause low power from the engine. The diaphragm style pump cannot be
cleaned and rebuilt.
The transfer pump is mechanically driven by a lobe on the camshaft. Wear on the lever or a damaged lobe can
reduce the pumping action.
(A) – Do not operate the fuel system with a suction restriction of more than 100 mm [4 in Hg].
If the diaphragm ruptures, fuel will drain from the weep hole (B) in the housing.
Normal pressure drop across the filter is 21 kPa [3 psi], maximum.
The pressure drop will increase as the filter removes contamination from the fuel. Therefore, a worn transfer
pump will have reduced capacity to force fuel through a dirty filter. This can cause low engine power.
NOTE: Frequent filter replacement to get full power from the engine can indicate a worn transfer pump.
