Replacing Weber carb
 

Hello, new member here, don't exactly have an offshore power boat, but this site seems to be the best resource online! I am working on a Maxum 2300SR for my dad. It has a 300HP 7.4L Mercruiser with a Bravo3 outdrive.

It exhibits a hard starting problem similar to others that I have read about on this site. It starts and runs great 80% of the time, the other 20% it is a PITA to start. Acts like it has no fuel after sitting for 1 hour to several days.

So, I think I have come to the conclusion that the stock Weber carb should be swapped out, as it has a poor reputation from what I have read. The boat is a 1995 with 270 hours, so the carb probably needs a rebuild anyways.

Should I swap out the Weber for an Edelbrock or a Holley? The Edelbrock sounds like it is plug and play, but maybe is not as good of a carb as the Holley and may not fix the starting problem? What needs to be changed to install the Holley? Fuel line and fab a new throttle bracket?

Thanks for the input!

The Weber you have and the Edelbrock are the same Carter design.

Having had that same engine/carb setup in the past I can tell you if the Weber is not leaking fuel for some reason and is properly setup with a properly operating choke and float levels, it's no more difficult to start that motor than with any other carb. While a brand new carb is always nice and may help the problem is not a carb design one.

Assuming the Weber is not defective, be sure to pull the throttle back to near idle to allow the choke plate to close while attempting to start the engine. Too many people try to hold the throttle wide open or pump the throttle while starting, defeating proper choke operation.

The weber style carb is not a bad one...same as the edelbrocks, for normal boating they are fine...look into fixing what you have..may just need a carb rebuild....they are not bad to do, use a edelbrock carb kit from summit jegs etc

I have the 7.4 with weber carb. Had the same issues as you, then rebuilt, and got the choke working correctly. Took a few adjustments, but now it fires up as easily as any carb. Remember that after sitting, a carb will not fire like a fuel injected car. Especially after weeks without running. But, mine now fires within a few revolutions and fires within 10 seconds after sitting weeks.

Also, check your fuel pump - as they get weak, they can make starting after a few weeks off a nightmare, as they don't reprime easily at cranking speeds.

I had the exact same problem, with the exact same symptoms in my 96 crownline with teh 7.4 and weber carb. I thought it was the carb also.

If you have the belt driven water pump / fuel pump........
Check the fuel pump. There is a set screw that needs to be removed to lubricate it (takes the same oil as the outdrive)

Most people don't check this. The diaphram wears out, and fuel pump loses psi. Then it takes a while (starting) to get the fuel back to the carb.

I found this out, because eventually my fuel pump almost locked up, and threw the belt. Replaced the fuel pump, and problem went away.

Well, it sounds like a bit more tinkering with the Weber is in order! Thanks for the advice. Scott

BTW, the rebuild kit for the weber can be hard to find - however, the rebuild kit for the Edelbrock works just fine - they are exactly the same except for the choke.

Once you have the carb, rebuilt or replaced, also check your coil. I had similar problems with my 454.