i have a 502 mpi and its not filling the water separator filter with gas any ideas before i start tracking down the problem

it could be a few different things,the fuelpump should run for a few seconds when you first turn the key on,check the check valve on the fueltank outlet,i had on get shavings in it,appearently,when the holes were drilled in the fueltank,the chips&shavings never got cleaned out,finally some of the junk got stuck in the checkvalve,causing the pump to loose it,s prime.all gas powered boats are required to have the checkvalve[uscg],hope this helps.

Fill fuel/water seperator with fuel and then screw on if possible. Might need a little prime for the pump.

i took the filter off the pump came on like it was priming but no fule came out the system to the filter.

it also would not hold a stedy RPM while running. it would move about 200rpm each waya. also it was poping trying to plain out and is some hard truns. when i stoped to check it the idle was ruff. then once i killed it ,it was over no cranking it back up. changed the filter and it would fill. i am at a totle lose on what to do? so i guss its to the shop with it!

Last year first run hit the throttle to get up on plane engine sputtered and stalled. tried it again same result. Not sure what the 502 uses for pumps but the 496 HO's have 2 a low pressure high volume to get the fuel to the other which is a higher pressure pump for the injectors. Long story short the low pressure pump sort of wasn't working. Got a new one for just over 2 bills. took the old one of rigged it up to bench test it with a battery charger some garden hose and a lawn mower fuel tank. first try got a little uh out of it second try uh and then a little lower toned uhmmmmmm and the fuel started flowing. Put the old one back on and run it all season about 50ish hours.