November 30, 1960
Bulletin No. SB-814
Fuel Pumps
SUBJECT: FUEL PUMP FAILURES - 35 & 40 H.P. Engines
Fuel pump failures on 35 and 40 H.P. engines have been reported at various
times; however, tests of some of the pumps sent to the factory have shown
most of them to be satisfactory.
Further investigation has disclosed this type of failure to be caused by the
entrapment of oil in the fuel pump which effects the output of the pump.
This oil, which originally is part of the fuel mixture, enters through the
elbow (306266) located in the transfer port cover. It will collect over a
period of time and finally affect the flow of crankcase pressure actuating
the pump or the action of the pump itself. When the pump or hose is removed,
the oil will drain away.
We have found that enlargement
of the original 3/16" hole in
the elbow (Fig.1) to a 7/32"
opening (fig.2) will eliminate
this problem. All elbows used
and serviced now have this new
size passage.
This modification can easily be made in the field. Remove the elbow and
redrill the passages to the new 7/32" dimension. Blow out the line leading
from the elbow to the pump and reassemble.
The modified elbow retains its original part number (306266).
We recommend that these elbows be checked as part of your routine tune up and
modified or replaced, as necessary.
JOHNSON MOTORS
W. W. DeWees
Service Department
WWD:eb
NOTE: Post on your RD index - 35 & 40 H.P.
W. W. DeWees