1973 Mercury 1500 hard to start?

I have a 1973 Mercury 150hp inline 6 that is hard to start when cold. Warm it fires right up. Rebuilt the carbs, new plugs, max advance at 20 deg., 100psi on all 6 cylinders.(A bit low but even) Has to crank for 2 minutes before it starts when it's cold? Pumped the ball primer, tried choke or no choke. Tried throttle or no throttle. Still takes a couple minutes to start. Anyone have advice on what to check/try? Starting fluid works but hate to do that everytime I start it. Need a newer motor.
Thanks in advance for any advice

Re: 1973 Mercury 1500 hard to start?

First of all stop using starting fluid as there is no lube in it. Use pre-mix in a spray bottle if needed. When starting the first time pump up the primer bulb, turn the key on, push it in and hold it while counting to 10 slowly. Then start normally.

Re: 1973 Mercury 1500 hard to start?

As Bill said, choke the crap out of her, when cold starting. Cold start lever all the way up, pump the primer until hard, hold down the choke button and crank her until she starts. You cannot flood that motor.

Re: 1973 Mercury 1500 hard to start?

Thanks guys but the only way to start it when cold is to pump the primer bulb till gas is running out of the carbs. And that aint easy since I just rebuilt the carbs and put in new needles and seats. It fires right up when warm but if you fish for an hour and want to go forget about it. You have to open the rear cover, pump the bulb, and crank it for 3-5 minutes. Thought there might be something I was missing. Starter and battery wont last long like this. Need to try an electric fuel pump with a small tube running into the bottom carb so I can shoot some premix in when I want to start it. Hate having to smell gas from pumping the crap out of the primer. I appreciate the advice though. Thanks

Re: 1973 Mercury 1500 hard to start?

It shoudln't that that long to start, something is out of wack. Do a link and sink. For my 84 115hp i-6 i found that i was using too much choke, i choke on the first crank and she almost starts then lay off on the second and she fires right up. I increase my idle to +/- 1500 RPM whem starting and to warm her up.