Had a wierd incident with one of my fuel pumps last time out. I've got a 99' 28ft Advantage sport cat with twin blown BBC. The motors started out as 600SC mercs and have since been upgraded to 800's. (superchillers, cams head work and upped boost). The mech pumps mount externally to the raw water pump and are driven by a v-belt. Last time out after a run, there was oil that had squirted out of the mech pump from the small "vacume" type port. I checked the mounting bolts and they were a bit loose. I tightened them and after another run a tiny bit of water seemed to come out. After that it was fine. Is there anything I should be looking at and checking to see if it is alright. Any advice would be appreciated. BTW the fuel pressure stayed at 7psi under boost.
Darrell.
I have seen the fuel pumps mounted to the seawater pump but I am not that familiar with them.Do they run over an oil bath or is there just grease inside the pump to lube it?
There should not be an open hole on the fuel pump body.A marine mechanical pump should have a hose running up to the air cleaner from that port you are describing.Without it in the event of the fuel pumps diaphragm failing fuel will spray out of the pumps weep hole into the bilge.
502 jet
I think your right, I should run a hose from the vent to the carbs incase of a failure. As far as an oil bath, for the pump I'm not sure. I need to get a hold of a manual for the motors. Hoping someone was familiar with the setup.
Darrell.
The fuel pump arm is lubricated by merc HP gear lube. It should be changed every year and inspected for fuel contamination. If there are any signs of fuel in the gear lube replace the pump. No.... you cant put on any fuel pump. The arm is different and you have to get a Merc pump. There should be a clear hose from the fitting to the carb to monitor for leaks in the diaphram and to keep fuel from spitting into the bilge when the fuel pump starts to fail.
Havasu47.
Thanks for the info. Hopefully I'll be able to get manual here soon, so there won't be any guessing.
Darrell.
The fuel pump arm is lubricated by merc HP gear lube. It should be changed every year and inspected for fuel contamination. If there are any signs of fuel in the gear lube replace the pump. No.... you cant put on any fuel pump. The arm is different and you have to get a Merc pump. There should be a clear hose from the fitting to the carb to monitor for leaks in the diaphram and to keep fuel from spitting into the bilge when the fuel pump starts to fail.
Well, here is an update. I pulled everything off this past weekend. Good news is the fuel pump is perfect. The bad news is the raw water pump was leaking h2o onto the oil resivior for the fuel pump. I ordered a new assembly. (ouch) Over $500 bills. I am going to try to get ahold of a complete rebuild kit from mercruiser with all the bearings and seals fot the one I have. Always good to have a spare.
Darrell.
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