Reply To: Evinrude 90HP 1999 “NO OIL” ALARM

[BobKoch]

So I was able to purchase a used Oil Lift Pump #5001504 on ebay (<$50) and thought why not try it.  While previously looking over the hoses and fittings for leaks I had already determined that this was not the original Pump on the motor some of the clamps did not look like factory etc.  So as I was removing the old pump from the mounting bracket I noted that the (2) screws on the rear of the pump were loose,  less than finger tight.  As it happens these rear screws are difficult to access with a wrench.  All (4)  mounting screw holes are clearance in the pump housing and are threaded into the mounting bracket thereby also clamping the housing halves onto the diaphragm.  The (2) loose rear screws could allow the pump diaphragm to leak because the pump housing is not clamping onto the diaphragm uniformly.  After replacing the pump, and tightening all (4) screws with a wrench the engine has been run several times and the “No Oil” alarm has not sounded.  Great!  So it could have been a hole in the old diaphragm or just leaking because of the loose mounting screws.

The current plan is to run as is for a few more outings and if problem free I will order a new factory pump and replace the used one I purchased from ebay keeping the used one for a back-up.

Thank you to everyone that commented on my post and provided suggestions.  I will definitely use the Antique Outboard Motor Club as  a resource in the future if the need arises.