Hey guys,

What would cause this:

After the boat sits for a week you must pump the throttle probably 20+ times while cranking it over before the motor will start for it's FIRST time. I'm assuming I have to prime/pump the throttle so much to get fuel up to the carb cause of a leak or ???

If it is being started up again thereafter or even the next day, then it starts right up. Only happens after it's been sitting for several days or more without running.

Stock plain carb'd Merc 454 w/ 300 hours in a 1996 Checkmate

What carb do you have? Is it a Quad jet or a Holley? You don't have any signs of a slow leak on the carb anywhere, do you?

When I had that engine in my Checkmate I found the best way to start it cold was a couple of pumps and then bring the throttle back to near idle before starting and leave it there. That would ensure the choke plate was closed while you were cranking. Is your choke working? Do you get a good solid stream of fuel from the accelerator pump?

Thats kind of common on the webber carbs on those year engines.

Both of my 7.4's would do that if left sitting for a week.

Like was said the webers all do that. Pump it a few times first, before cranking. Return the throttle to a slightly forward position.

Where do you boat at ???

My weber did the same thing until I got the choke set just right. Make sure the choke is closing enough, and the idle setting isn't too lean. Now, prime it once, a few seconds of cranking, and it fires right up.

mine do the same thing. After a week they take forever. Withing 2-3 days its starts right up

I'll have to check the choke then. I'm a very experienced EFI guy, but do not know anything about carbs. Guess i'm too young! Are there any good articles/walk-throughs on how to adjust the choke and various items?

Shelbyville, Mark Twain, Litchfield, Alton Pool mainly

I boat at Kaskaskia for the day, Kinkaid a couple times a year, Norfork at least once a year this year twice, usually go to Alton pool once a year.