Why is my boat hard to start 90% of the time? It cranks and cranks and then starts. It has never failed to start and runs fine once it starts, no missing no fluttering no nothing. This happens when unloading from the trailer, when 30 seconds after it is shut off if you try to restart same thing. 1 out of 10 start are imediate. When unloading from the trailer I have checked and the choke is working fine there is not fuel overflowing onto the throttle plate, fuel bowls have fuel in them and the squirters are working. When I shut boat off on the water I pull the arester and no fuel seapage at all, the squirters still squirt so I assume the bowls are still full. I have to crank it about 20 seconds to get it to start.

Boat has the stock Mercruiser electronic ignition and new original carb.
1994 74. liter

My first thought and question is does Mercruiser use a higher voltage wire to the coil like GM does when starting? Older GM cars when cranking the engine over had a wire that ran from the starter to the coil for more voltage, does Mercruiser use this same method?

Any other thoughts?

No the Tbolt IV coil gets a full 12V all the time. It could be weak though. You can buy a $12 GM (external resistor) coil from an auto parts store and see if it works better. No resistor needed with it, just swap it out.
Does it have a weber (carter) or Qjet on it? The carters seem to do this a lot, not sure why. Have you tried pumping it once or twice before cranking?
Gary

Twice, four times, six times. No difference. I believe the carb is the Weber. The prior owner bought it new as a replacment just before I got the boat. My guess is he was trying to fix starting problem....

I think I will take a test light and a meter with me this weekend and see how the voltage looks while cranking.

Come to think of it, the only time it starts easy is if the boat sits in the water overnight. Then the first time I start it in the morning it starts easy.... Hmmmm, sure sounds like a float problem. Boucing on the trailer, then bouncing from waves, sits all night and starts right up. I will double check my theory this weekend.

Have you tried not pumping it at all on re-starts? What works best for me on restarts is no pumping, but move the throttle forward about 1/4 then crank. You never did mention what carb you have. I run qjets. Mine starts best after a night of sitting as well. I have tbolt IV ignitions and can run with or without msd and blaster coils. Don't notice any difference with the msd.

BT

my 4.3 has done that since i put the new edelbrock (weber) carb on it. it always starts though. somebody told me it was my fuel pump going bad. I havent ever got around to messing with it because it runs great and always starts. I have had the carb on there for 2 seasons with no problems though.

That is a typical problem with engines that have Weber carbs. I know. I have a '93 and it did the same thing. I put a Holley 800 on this year and the problem is solved. The boat can set for two weeks and it still fires right up. I also gained about 1.5 mph, too.

I removed my anti siphon valve from the fuel line and I get much easier start ups every time, used to have the same problem and I have used four different carbs from stock to Edelbrock and Holley. I am getting 3 lbs more fuel pressure without it as a bonus.

where is the anti siphon valve i dont think mine has one

Mikev--- If you are the original owner, you probably have one . The valve is located near the fuel tank. If you pull the hose from gas tank , there is a ball and spring inserted. This was a safety measure instituted by the marine industry. P.S.- my safety was removed years ago.