posessed formula
 

HELP. My friend has a 30 foot formula with twin 454s. The starboard engine keeps sputtering and quitting, the next trip it runs perfect, no ryme or reason to it. We have changed water fuel seperator, fuel lines, check ball in gas tank, fuel pump, coil,switched the in line fuel gauge which may be a clue, it is supposed to have 7-9 lbs of pressure but goes up to 25+lbs, anyone have any ideas.

check the 2 wire ing pick-up in the distributor, under the rotor--usually go

X2

Could be a bad fuel tank or just a lot of crap in it. Clean the tank out and see what you find. I went thru a similar thing with our houseboat. Ran good until you filled it up with gas and stirred up the tank. Always a good idea to flush the tank out every 2-3 years. Our tank needed replacing - it was steel and was rusting internally (1973 houseboat). Was like a orange thick crayola paste when we were cleaning out the carbs.

fixx
 

25 psi of fuel pressure????? is it regulated? if so adjust the regulator,if its hard mounted and going over waves could make the regulator spike to a higher pressure,i like to nount them to a recoil bracket that will flex,,somthing like a 24g piece of ss metal..

also if it has a alunimum pick up tube in the gas tank they are prone to crackwhere they screw into the 90* fitting causing the fuel pump to suck air,if you have a full fuel tank it will be ok until the fuel goes below the level of the cracked threaded part of the pick up tube.

check the big multi pin plug on the main harness that the motor plugs into. Take a small jewelers type flat blade screwdriver and gently pry each pin open to ensure they make contact.

If GlassDave's approach does not work, replace the wiring harness. Give mercruiser your engine serial number, they will send you the right one. Plug it in. It takes a little while, you might scratch knuckles, but its not too hard. Its MUCH cheaper than all that junk you've already changed.