Well, they are not radically different inside, but orientation of the fuel line outlet differs as does the orientation of the pump mounting screws, some are vertical, some horizontal. The other issue is that oftentimes you will see a tab on the fuel pump saying up with an arrow, this must be pointed upwards or the pump won’t work properly….
The used pump I pointed out is the original part number for the 4hp 381815, which supercedes to the expensive new part number….
At this point, my curiosity has peeked…I would probably take the risk of buying the OMC rebuild kit, then pulling your pump apart to see if it can be rebuilt….Or, better yet, pull it apart first and post pictures….Looks like the kit has new inner housings/springs/cups that might replace the original flapper diaphragm system….
Again, please be very careful disassembling your pump….Get an indullable white marker to draw a line across all the plates/plastic housings, this will ensure all the pieces are properly oriented during reassembly. Be very careful pulling it apart, do it in a clean white bucket to keep bits/pieces from flying away….
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