Bertram 28 Moppie Fails to start

Sounds like your mechanic is right on target, but have you checked the choke (often activated by pushing in the key)?

You could have a few different issues going on from what I can think of. How long has this issue been going on? Electric fuel pumps should solve the problem but must be tied into a safety switch that won't let the pump run unless there is oil pressure or such. IMO, it may be putting a band aid on another problem. Without looking at the boat here are some thoughts as what the problem could be. If you have been running any fuel with ethanol in it, it's possible your fuel lines have deteriorated and are letting air into the system or collapsed inside. The carberators could have leaking bowls on them allowing the fuel to leak down into the motor when the boat is sitting (rochesters are notorious for this), and would need to be rebuilt. Your fuel filters could be plugged. If both motors are doing it, I would look at replacing your fuel lines first. Even if the tanks are lower then the motor (and most are), they should start up without resorting to starting fluid.

Both engines? Do they share the same pickup in the tank? A quick test is to put an outboard style primer bulb at the fuel tank,after sitting "7-8" days you could pump up the system till the float in the carb shuts off. Then see if it starts right up,as you pump the primer bulb look and listen and smell for leaks as your now putting pressure on a line that sees only vacuum up to the fuel pump. Also pickup tube may be holed,you would need to remove it to inspect. It's going to take some poking around to find this problem.

I don't know how anyone can answer your question without knowing what the engines are.

What year and model are the engines? Are they gas inboards? EFI or carbureted?

I have seen several different models that have this problem from the factory. The solutions are completely different depending on the model.

With more info, I may be able to help you.

Actually, all those questions are answered in the fist post."1988 Bertram 28 Moppie w/ gas engines (Mercruiser)" "into the carbs" and the problem is with both engines.

Ah, you are right that is in there.
The next question is if those engines (with the model number or serial # i would know) have the Weber carbs? And if Weber carbs, do they have mechanical "heat stove" chokes"?

The early engines (around '88) are the ones that had hard starting problems.
there were three causes for the problem. ( I was a tech at a sea ray dealer in 88 and every boat we delivered had this problem. I actually worked with a Merc engineer to diagnose the issue in person.)

The problem with the Weber is that the bowl is low, flat, and wide. It is like a frying pan. When you shut the engine off the remaining fuel in the bowl vaporizes very quickly. When you go to restart the engines, both bowls are completely empty. Pumping the throttle does no good because there is no fuel in the bowl for the accelerator pump. Some of these engines also had electric fuel pumps that are wired though an oil pressure safety switch. They also had a poorly engineered mechanical choke system that barely moved the choke rod at all from cold to hot. Lots of problems here....

When you try to start it.
1. empty bowl and no pump shot
2. weak electric fuel pump that doesn't even come on until you build oil pressure from cranking
3. a choke that just flops around and does nothing

Without re-engineering the whole thing the situation can be improved this way.

1. run the blower after shut down to cool the engine compt
2. set the mechanical choke closed tight. Set the choke pull-off also tight. This gives it full choke while cranking but snaps it open as soon as the engine lights. This way as soon a fuel hits the bowl the engine sucks it right in. (or convert to electric choke, as mercruiser did with this model later)
3. procedural- when you start these engines, crank them twice for 10 sec each with a pause in between. This builds fuel pressure in the fuel line and the bowls will continue to fill up even while you are between cranks. Then, two pumps and a almost closed throttle.

Do this and they will light right up every time.

One other thing. Adding an insulator between the carb and manifold also helps quite a bit. These can be found at a hot rod shop. You may have to re-bend the fuel line slightly to re-attach it. Do not replace with a rubber line.

Let me know how it goes..

Now that is very interesting. So the real cure would be to swap out both carbs (which is expensive). The alternatives would be to learn to deal with the boat's personality or add the fuel pump. I think I'd still go with the pump first, especially if the carbs are otherwise working well.

If you could put a primer button or primer pump in to fill the carbs up before cranking the engine that would really fix the problem. However this is hard to do without compromising the Coast Guard approval and re: fuel systems and ignition protection so I don't recommend it.
The two short cranks before trying to start it and the other minor changes work pretty well.

If someone says, "well it worked fine before", that may be the case but the real problem (that you can't solve) is the fuel quality. Fuel has changed since 1988. This system was marginal even then...
Winter blend fuel and ethanol really aggravate this problem.

EFI engines are not immune either. We have been through multiple updates and recalls to solve vapor-locking problems on those.
The newer engines are designed with this poor quality fuel in mind and handle it pretty well.