if fiddling with the base gasket caused a reaction ... I would continue to focus on the pump base & gasket before going OEM...pump. carefully apply a light coat of sealant on both sides of the pump gasket and remount. I have never seen the need to do so by ...hey we can't see the problem...
2 man job.... one pulls one feels you have no options but to confirm pulses or not because buying an expensive OEM square pump will not solve the underlying problem... fuel must reach the carb.
ok first things is never give up...when reassembling these pumps mounting a few critical parts properly helps the reassembly ... mainly the springs ( big and tiny one with mushroom heads.
To make certain they do not flip over I always wet the spring base with crazy glue to hold things...
if not a pump issue cc pulsing may be weak due to a crankcase sealing problem ...if reeds are ok a volume flow test will confirm.
or check with a vacum -pressure meter on the pulse port
if it worked with gravity feed ! the pump is not doing its job cyl comp. does not concern the fuel pump it runs on crankcase pressure build up when the piston downstrokes. Do the flow test suggested above fill the bowl.... pull the carb inlet hose..... and run 2-3 minutes ... measure...
based on AI ... say (1.5g/hr x 128 ounces / 60 minutes) x 3 running minutes shoud produce the 9.6 ounces of fuel at low pressure
AI said....
A mechanical fuel pump on a 1976 9.9 HP outboard (whether it's an Johnson or Evinrude two-stroke) doesn't produce much pressure, but it does produce...
tricky thing here the engine works fine and the fuel hose is brand new so it seems doubtful a gray line would have self destroyed itself so fast. the carb is not being replenished by the fuel pump .
one test would be to actually measue the volume of fuel pumped towards the carb inlet WHILE...
does it die idling or at wot.... remove the pump confirm that you feel a good pulse out of the pulse port .. if you do them recheck your pump reassembly
if it only dies idling recheck carb low speed circuit and & drip chamber under top welch plug if never inspected
lift fuel supply...
the engine needs fuel..and when you are supplying it manually it runs so one assumes hoses are ok, few items to check...
make certain tank venting is ok
disconnect carb inlet fuel hose and crank the engine to confirm fuel spits out the hose to confirm the pump is or is not ok sucking fuel...
you could try to tap it lightly on the end to fatten up the diameter and drive it back in
you could run a (greased up ) tap in the hole and close it up with a bolt and blue lock-tite
starting involves proper choking when cold or dormant for hrs... carbs must be 100% clean especically low speed cct.
check fuel pump fill (reprime) carbs check fuel hose check venting
