It's not uncommon for fuel to evaporate out of the bowls when it sits a few days.
Buying a shopping cart full of "new carbs" won't change this.

There are 2 ways fuel will "leave" your carb.
1) evaporation
2) leaking

Evaporation is normal. Heat accelerates evaporation. Airflow around the carbs accelerates evaporation. If you trailer your boat, driving down the road circulates air around your carbs. If you dock your boat where there is a breeze, air will circulate around your carbs.

Leaks can be external or internal. External carb leaks will drool fuel ONTO the intake. Internal carb leaks will drool fuel INTO the intake.

Once fuel has evaporated from the bowls, there is no chance the motor will start and run until the bowls are filled to the proper level. Not just enough for the squirter to work, but to the proper level else the idle circuits will be too lean to support steady idle.

You've mentioned that you aren't running chokes. There's very little performance penalty running a choke plate and electric actuator.

Now, filling the bowls can take a lot longer if your fuel has leaked back to the tank. Normally, a mechanical fuel pump will totally prevent fuel to backflow to the tank unless its check valves are leaking. But ANY small air leak between the fuel pump and the tank pickup WILL allow fuel to lose prime. Fittings at the pump inlet, the water separator inlet and outlet, the screw on canister filter seal, all of these can allow fuel to drain back to the tank if there is any leak whatsoever. Leaks BEFORE the pump go unnoticed because it is a suction line might never drip fuel.

So, check EVERY fitting and junction between the fuel pickup and the fuel pump inlet. Disassemble. Clean. Fresh Teflon tape. Securely tighten fittings. Replace hard or stiff hoses with new rubber. Double clamp with good wormgear clamps. Clean the sealing surface for the water separator canister. Oil or grease the seal on the canister and tighten it properly.

As far as the fuel pump itself, there are plenty of high volume mechanical marine fuel pumps. You should use a marine mechanical pump because the diaphragm vent is routed thru a hose to the carb to keep fuel from dribbling out into your bilge in the event of a ruptured diaphragm.
But I'm not sure I understand your aversion to an electric pump, especially since this is a common problem AND you run carbs with no chokes.
The usual way to wire a marine electric fuel pump is to run a hot lead from the coil + terminal to the fuel pump relay. The ground for the relay coil should run thru an oil pressure switch and also from a momentary switch at the dash.
To PRIME, you turn the key to "run" then press the momentary prime switch to fill the bowls. Then release the prime switch (the pump stops). Then pump the squirter a couple of times and hit the starter. Pump the throttle as needed, knowing for certain that your bowls are full. Initially, the pump won't run but as soon as engine oil pressure rises above 15 psi, the pump starts running again. Then, if oil pressure drops (engine quits or something happens where you lose oil pressure while running) the electric fuel pump stops. Or. Of course, when you turn off the ignition.

That way, the pump automatically turns on and off when you start or shut off the motor, and anytime you want to prime the carbs, just turn the ignition to "run" and press the prime button.

Something like the Carter Marine rotary vane pump should work ok alone for up to 500hp, as long as the anti-siphon and filter are free flowing. If you are "on the fence" on whether it is enough pump, you can keep the mechanical pumps to cover the question mark.

Just know that the mechanical pumps won't be able to suck fuel thru a "not running" positive displacement vane pump. The electric pump must be running in order for fuel to make it to the carb.

Also make sure your accelerator pump cams are in place and adjusted. I purchased a couple of 1150 doms that were new but were on display at a speed shop. Needless to say when initially checking the carbs out I quickly realized the primary excel pump cams were missing on both carbs. Not a biggy and seller immediately sent two replacements. Doubt your problem if your having same issues before and after rebuild unless.... I don't believe your issue is evaporation unless your floats are set dangerously low. Again if you can reach in and take a pic of both sides and the top of your carb minus flame arrestor would be helpful for others to maybe solve your problem. You can R&R a carb and let sit on the shelf for a week and still have enough fuel to start without priming. If you can't post pics ask a member to do for you. If your arm can't reach back far enough for pics then I'm not sure what to say.

I think I lose my mind
 

This is a fun game playing guess what carb.
A monkey can post picture, post a damn picture already.

Made me think of this Prosystems meme :)


https://cimg6.ibsrv.net/gimg/www.off...f93f4e225.jpeg

NO bro.The state is nothing but outboards. Big ass cruisers without boards for five even six outboards. Somebody gave you the wrong information but I always are not very plentiful

Hey Griff, thank you for your nice calming words and none agitating sentences. Replacing parts on a carburetor was done by him and he tuned it to the best that it could be tuned. Still with no improvement.If you have a question for him I can just give you his phone number so you Can bypass me and go directly to him. Now back to the boat. after the carburetor rebuild it acted exactly the same. As far as the float bowls being set, again you can ask him I’m sure he would appreciate it.I realize this is irritating for you which it shouldn’t be since you saw the need to reiterated to the Forum about working on car since I was 12, can you imagine how I feel trying to work on motors since I was 12 and you were trying to figure out which end of the pacifier to Use since I am 76 years young?Now back to the boat. I contacted Holley about their EFI system. They do have a marine system but the problem is the O2 sensor And water Don’t interact with each other very well. the carburetor is Coast Guard approved they cannot approve the remainder of the system and I don’t think I really want to be responsible should it blow up. I again will attempt to get some type of number off the carburetor Just to satisfy your curiosity. Maybe I need to clean the carburetor body that is underneath all the grime from the leaking fuel and you can tell me what that has to do with anything. I would really appreciate Your input Griff.Sounds like you know much more than I do about site plugs and Carburetor numbers.thanks for your Advice bro.I just couldn’t resist?

Huh ? I go to FMB every 2-3 years and yeh, there is more outboards every year but still bunch of performance boats. More older guys (50+) than younger know carbureted systems (this includes their ignitions and fuel systems)and there is no lack if older guys in Fl.

If your ever up in NH I’ll take a look for you.That’s the best I can do without more info / diagnostics /carb and rigging pics /etc

Will do and if I get him some pictures for you I’ll send them To you and thanks bro

You first step, and really your only step, should be to find a mechanic who knows what they are doing on carbed SC engines and can diagnose the issue and check over the entire engine.

I could walk you through a half dozen things to do and check, but its pointless because you have pretty much said that you are not going to do it. No reason for me to tell you what any decent mechanic who works on carbed SC'd engines will already know to do. Looks like you've been dealing with the issue for a year. Find someone who is competent who can diagnose and fix the issue.

I understand the frustration/ brain fry - EVERYONE seems to be an EXPERT until they show their cards for what they are...

Question - Are you will/capable of trailering the boat to Pompano Beach?
If yes, Jason is your man (or can possibly refer to a shop closer to home). He has a resume most shops dream of....
https://www.bxpmarine.com/