I have 1979 150 mercury v6. It has always been a little cold natured ( hard to start the first time of the day ). Once it has warmed up it will fire right off everytime. I replaced the water / fuel seperater, rebuilt the fuel pump, replaced the fuel line and squeeze ball, new spark plugs. Still it will almost run the battery down trying to start it that first time. Once it is running it runs great so I dont think there is anything wrong with the carbs. And if you spray a little gas in the carbs it wil fire right off.
What should I check next.
Thanks in advance.

Do you tuck tha motor all tha way down? That motor has choke flaps instead of the enrichment stuff and ya got ta stuff a lot of gas in it at tha first start of tha day. Just tha nature of tha beast. Try this and if it don't work then ya may have some kinda deliverly and/or timin' problem. Pump tha blub till its as hard as ya can get it then squeeze it a little more. Tuck tha motor ALL tha way in. Move tha fast idle up just a tad. Choke and start at tha same time. It will probably sputter and try ta fire. When it does this get off tha starter and choke. Ease a little more fast idle with NO choke and start. You might be doin' this already. If so it might be a fuel or idle timin' issue............T

I lower the motor all the way down and usually pump the ball until it is tight, then pump the hot foot several times and hold about 1/4 throttle and choke /start at the same time. once it spits and sputters which takes a little while and quite a bit of cranking, then I usually have to pump the hot foot several more times and repeat the choke / start. I will try it without the choke after the spit and sputter.
I dont think it is a timing issue because it runs perfect after it starts.
Could be a fuel delivery problem, it acts like after sitting over night the fuel may be leaking out or draining back down or something. I have noticed fuel and oil on the motor mounts and in the transom splash well, before I rebuilt the fuel pump.
Any other ideas incase this doesnt work.

Don't PUMP tha hot foot, just hold it down at first. After tha spit/sputter back off just a little. If that don't do it ya might have a problem. I had one just like it. Just a pig ta get it started no mater what we did. And we did everything. ie: fuel lines, tank, filters, pump, carbs and even electrics with no change. Finally went ta wh15's and enrichner and cured it. Hope ya find it.........T

What is this ?

Just a little info. Being a non-fingerported, piston port motor there's not near as much fuel going inta tha clyinders as it might appear ta be. Nother reason this type motor burns more fuel than tha 2.5's........T

TLW , I really appreciate all your help with this. Definately gives me some new things to try tomorrow. What is wh15's and enrichner?

Later model carbs that can use tha enrichner. Tha enrichner flows fuel thru tha carbs straight inta the reed plate(instead of chokin' off all tha air)....T

Okay, I'm going to list some points of interest. None of them are intended to insult your intelligence. I'll list them least expensive to most.

1. You know for a fact that every cylinder is firing? You have performed a spark test or a drop cylinder test.

2. When you rebuilt the fule pumps you also changed the under cowling fuel filter that is inbetween the fuel pump and carb?

3. You have replaced all of the under cowl fuel lines at least once every ten years. If they are original (I doubt it) it wasn't until the late 80's that all sppliers switched over to ethanol resistant fuel line.

4. If you have replaced the fuel lines you periodically check all the hose clamps. I've never seen hose clamps loosen on my truck, but I frequently find those little suckers on my boat needing attention.

5. You have had to replace the stator and/or trigger and whoever did it for you did a sloppy job on synch/link and timing. Merc timing can be done running or cranking. Running is more accurate.

6. Haven't decarbonized your head lately. No problem. Grab a one gallon gas tank, add 16 oz of Seafoam, add your premix and top off to a gallon. Place fuel line from motor in tank, start and run at high idle for ten-15 minutes, let cool for the same amount of time, repeat until gas is all gone. cheaper than treating the whole tank

7. For added measure or quicker, pull all plugs, saturate cylinders with DeepCreep, replace plugs, allow to sit overnight, start next morning. Be prepared for ALOT of smoke. Excessive carbon can really make a Merc cranky.

8. Finally and what I think it is most likely is that either the starter is tired from grinding down the battery or the battery is tired. Find someone with one of those mobile power pack, clean all you connections, hook up the power pack to your battery and turn the key. More than likely you will see the starter has more life, spins faster and the motors fire right up.

I just reread your post. Mercs have two timing settings. Idle which is several degrees BTDC and WOT which is ATDC or vice versa. Check the manual for sure. It's not hard to check. Your timing could be off on one and not on the other.

If your gettin' fuel in tha cowl and down tha down housin' ya might check all tha bleed lines and tha cheezy merc clamps....

Rick, just remembered another instance many years ago with a 70 somethin' motor. After tha sputter we found out if we trimed tha motor up it would come ta life a little easier. Those motor's have a tuner thats as long as ya arm and it seemd ta help if tha tuner was above tha water at tha first start of tha day.....

Thank for the info. No I havent done everything that you have listed. But it sounds like I may need to take it to the guys at Fun-n-sun and let them check everything out for me. To be honest I am a pretty good shade tree mechanic but alot of what you said sounds foriegn to me. Another words, may be outa my league.
I was hoping that it might be something simple that I might have over looked. Sounds like it could be alot more than that.
Thanks again.

Not to hard to convert the butterfly choke system to a enrichment solinoid system. These early Mercs all were real cold natured. Have done several by drilling carbs for the hose fittings, install the fittings, mount the solinoid, tee the fuel line for supply to solinoid, install all hoses, connect choke wire to solinoid and your good to go. Or you can get everything from junk later model Merc and just install it. I should have what you need either way. Good Luck