1965 MERC 100 W/ K-ignition inline 6

[12volts]

I aquired a boat w/ merc. 100 inline 6, 1965. I had a mechanic overhaul the carbs. Got the boat motor running good. Problems since the first day out. The first thing is the motor usually starts with no problems, (dew mornings aside) when going out or anywhere for that matter Full throttle for 2 -3 minutes motor will start gradually slowing down to a complete stall. If i back off from full throttle it will be fine WOT 2-3 minutes same problem. Also After stopping and drifting for say 30minutes or so when starting if it doesnt catch on the first crank of the starter, it wont start unless i use starter fluid. (yes I Know this is no good) but what else to do 2 miles out from the dock. Once this motor is running it is fine. I have replaced the fuel lines to 3/8, new filter, checked tank vent, new bulb (unsure of name) west marine with gray hose, changed the merc gas fitting, bulb NEVER gets rock hard (have read the posts on that one. I have 2 -18 gallon tanks. I bypassed the switch and am only running one tank at this time. The tank is more of a vertical type than a horizontal and is mounted towards the bow under the captains chair a little more than mid way. Oh, one more thing also had the fuel pump diaphrams changed the same time as the carb rebuilds. any suggestions?

 

[MGuckin]

Re: 1965 MERC 100 W/ K-ignition inline 6

Have you tried using pre-mix in a spray bottle when the motor starts to stall?<br />If you have a manual choke, check for correct operation. <br />Check to see if you have an anti-siphon valve in your fuel tank. May be clogged.

 

[rickdb1boat]

Re: 1965 MERC 100 W/ K-ignition inline 6

12Volts,<br />Get yourself a different fuel line assembly with a new primer bulb(I know you've replaced it once). Get the OEM if you can. Try using a 6 Gal. portable Gas can and see if that helps. If the bulb won't stay hard when pumped up, it is either air leaks, the bulb is bad(Even New One) or the float needles in the carb. are sticking partially open allowing fuel to pass into the float bowls. I would try the simplest things first and replace the fuel line and try with a different tank. If the problem happens again, pull the spark plugs immediately and see if they are dry or wet. That will tell alot of the story.

 

[mellowyellow]

Re: 1965 MERC 100 W/ K-ignition inline 6

had same problem on my '70 1150, the wrench <br />installed the wrong gasket on the fuel pump<br />by mistake. if you looked at the 2 side by side,<br />you could barely notice the difference....<br />mine would start and idle OK and would only bog<br />down bad/die after giving throttle.<br />good luck,<br />M.Y.

 

[Trent]

Re: 1965 MERC 100 W/ K-ignition inline 6

Check valves in the fuel bulb or bad fuel pump diaphram can cause this problem. Replace the diaphram if its been awhile. <br /><br />Easy way to check for a bad diaphram is at WOT and she starts acting up pump the bulb. Does the problem go away? If so, its the fuel pump.<br /><br />When you buy a fuel pump kit. Make sure to get the one that has the check valves in it. Some kits just have gaskets and diaphram.