Wont idle/RUN

[Frankiea87]

hey guys im working on a friends boat -it has a 4.3l v6 mercruiser with a 2 barrel carb, first issue was i was out on the water for around 20 min and boat would stall out and would not start until it cooled off (sounded like it wasnt getting fuel)... anyways i changed the fuel pump (waste of money i believe) but i can now keep the boat running at high idle, Also changed the oil pressure safety switch (located on lower right side of motor near oil filter) , then i looked at the air mixture screw on the carb and it was loose and wiggled in its slot, so i tightened it as much as i could and was going to turn it 1 1/4 turn back out but its idling lower now but not where it should be (gauge is broken but i can hear !! ) .. probably around 1200rpm, i cannot get it to idle any lower without it stalling out, ANyone have any suggestions? carb issue? (electric choke always stays open for some reason.)

 

[Frankiea87]

anyone with any ideas? please help!!! need running by weekend :/

 

[dlvwill]

Need to take a sysytematic approach and not throw parts at it. How old is the gas? Does it contain ethanol? Unscrew the water seperator fuel filter and dump it out. Is there any water droplets? Then check fuel presure. If low <6psi, and with a new pump, then you have a supply issue, check anti-siphon valve, hoses, tank pick-up, etc. The mixture screw being backed out may be a clue as to prior problems, next would be a carb rebuild.

 

[Molson]

check anti siphon valve.