Rebuilding the new OMC Fuel Pump




The illustrations below are off OMC's fuel pump repair kit instructions #433519 or NAPA 18-7800
This same basic fuel pump was used on many motors from made from about 1987 thru the current models  for 9.9 hp up to
155 hp using non VRO.

However -- on the 9.9/15 hp motors from 1987 to 1992 depending on whether it came equipped from the factory with a electric starter or not, there was a different fuel pump.  If it had only a rope starter, then it was equipped with the older small square fuel pump, but if it had a electric starter then this newer larger fuel pump was installed.  For these 6 intermediate years repair kit #0398514 would have been proper for the electric start.   The pump body seems to be the same except the rear mounting plate.  Repair procedure would stay the same as shown below however.

NOTE -- These 2 illustrations are from scanned pages from the original repair kit.



This repair kit is for 1990 and newer 9.9 thru 155 hp model Evinrude and Johnson outboard motors without the (VRO) Variable Ratio Oil Injection System.

Some of the parts in this kit are not used in some applications.   Discard the extra parts.


(1)  Contents of Kit


Part Number

Name of Part

1 335334 Check Valve 2
2 318375 Air Dome Support 1
3 328779 Housing Gasket 1
4 332678 Diaphragm 1
5 328777 Cover Gasket 1
6 332694 Vacuum Housing Cover 1
7 319822 Large Cover O-Ring 1
8 324660 Small Cover O-Ring 1
9 303615 Pump to Block Gasket 1




(2) Disassemble your pump carefully, taking note of the position and orientation of each part.


(3) Place a drop of oil on the stem (A) of each check valve.  Install the check valves by pushing the stem thru the center hole with your finger tip or pencil eraser until the enlarged head (B) is thru the housing.


(NOTE)  Do not use your finger nail, pencil point or ANY OTHER TOOL to install check valves or valve damage and premature failure will result.  Do not assemble check valves into a dry housing, and do not pull valve stem thru the housing.  Never reuse a check valve after it has been installed and removed.  Removing a check valve damages it and reusing valve will result in premature pump failure.


Reassemble pump, hook up fuel tank and squeeze primer bulb to check for leaks.  Fuel leaks could cause fire or explosion.  Repair any leaks before operating motor.


You can see from the above information that this fuel pump is considerably easier to repair than the older one was.

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Originated 11-16-06 & last updated 12-15-2014
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