Offshoreonly.com - 330hp 454 dies at idle.

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Sounds like the coil is bad once it gets warmed up.

Richard, if the coil was bad wouldn't it get worse at higher RPM's. or show up as a skip at all RPM's?

Quote:

Originally Posted by Audiofn (Post 3426632)

I have an 18 Donzi with a 330hp 454 in it. The boat has always had a very small mid range bog but I never looked into it and assumed it was carb. It did not bother me enough to look into why. Last year all of the sudden after the boat warmed up it would die at idle. I rebuilt the card and it still did the same thing, replaced points the other day still the same thing. Anyone have any ideas. It starts up good, seems to run smooth for about 15 min then it will start surge almost like a blower roll, slowly at first then more and more tell it dies. I have not done plugs since I purchased the boat because I don't put a ton of hours on it. Maybe the stuff I use to winterize fouled up a plug? I have not tested to see what it is pulling for vacume. I am going to try and get a friend to help me out this weekend if he can.

When rebuilding the carb, was the carb soaked in order to clean all passages? also were the idle mixture screws adjusted?

No it was not soaked we just sprayed cleaner and then used compressed air to clean them out. Idle Mixture screwes I have messed with. When you get it running OK warm then it is a mess cold and vice versa. I am really starting to lean towards the carb needing to be rebuilt again.

Jon

Get rid of that quadra-junk, and put a holley on there. Simple swap...and easier to work on sir. :drink:

330's have run for ever on the Q jets. They are nice and efficient as well. Wouldn't I have a lot more fuel burn with a Holley and also have to swap over the intake?

No on both counts. :drink:

What intake are you running ? It more than likely has the stud holes in it for both style carbs, and if not...they make an adapter.

Here are a couple examples sir. See the extra holes ?

Have you watched the carb as it goes thru this cycle? Does the choke flutter and then close making the engine die?

I had this same situation on a truck I used to have with a marine q jet... Zip tied the choke open and no problems...

I asked him about the choke earlier....but he never answered back about it. ?????

Choke is open all the way sorry about that guys :D