1973 340 Sputtering when Accelerating

Hey guys,

I have been reading the site for a while and this is my first post. I recently bought a 1973 Correct Craft Southwind. She had been sitting in a guys storage unit for many years and I was very happy to remove it for him. I will post a few pictures when I get time later this week.

I have been having a problem and was looking for some help. The boat runs great until you get over 2200rpms, then it starts sputtering and backfiring. I replaced the points, fuel filter, fuel screen, condenser, cap, and rotor. I also made sure the timing was where it needed to be. The spark plug wires are fairly new. The boat ran a little better after I installed these parts, but will still bog and backfire at high rpms. The centrifugal advance mechanism under the cap seems to move freely, but I am unsure how to tell exactly. Any ideas would be appreciated.

-Dan C.

Thanks for the reply. That seems like the logical next step. I was hoping it was one of the easy fixes. Oh well, it will be a great way to learn the carb! Its been quite a while since I've taken on of those apart.

I noticed I was getting a bit of water in the bottom. I just replaced the original plug to see if it would fix the problem. Are there any other common culprits? The bottom of the boat is in good condition.

By the way it has the MOPAR 340ci engine. The boat has a great sound when wide open.

When I floor the throttle it will stall out and kill. If I ease it forward and goose it a little, I can get it open wide. It will run hard all the way up to 4500 rpm, but after a few seconds it will backfire out of the carb, sputter, and stall out. If I keep the throttle anywhere over 2200 rpms it will eventually result in the same type of behavior. Anywhere below 2200 rpms and it hums along.

I only checked the timing at idle. Could that be the issue?

I checked the engine compartment this morning and the plug was not the culprit of the leak. I was planning on taking the boat out this week, I just wanted to get a checklist together of everything I need to work on over the winter.

Yes, this is my first inboard. What a difference! I found out reverse is a bit of a diffferent ball game from an i/o.

Maybe the fuel pump diaphrams dried up in storage?

Make friends with the search feature here on the site. It's a fountain of info. One thing you might have found that way is that you can run the engine from a satellite tank to diagnose the fuel system behind the engine. Put simply, run off of a small tank directly to the pump. If that solves your problem, you know where to look or to not waste your time.

New to inboards...you'll luv it. Reverse is surely a different animal, but you'll get used to it. I'd also check your raw water pump impeller. It may be on its last leg if you didn't give it the once over already. Are you familiar with running it on the trailer?

Inboard tip-keep a spare impeller on board.