here we go
 

have a 3.0 mercruiser in my v20, i start it up and she runs fine in slow idle. once i goose it in neutral she revs up for a second and then dies, any ideas or advice would be helpfull, thanks :head:

Not familiar with the 3.0L but engines need fuel, spark and compression. If it idles well, it has compression and spark. I would then look at fuel. Has it been layed-up for any period of time? Might have a fuel flow issue (pump not producing enough fuel, clogged filter, fuel tank pick-up clogged) or it could be something wrong with the carb itself. Needle and seat, float, accelerator pump. It could still be something spark related. I normally start with spark and fuel. The gurus will be along shortly to tell you where to start. Hope it is nothin serious. What carb is on it?

carb
 

i just went out and got it to run for 8 mins at 1100 rpms as soon as i bumped up the throttle she stahls, i hope this would rule out a bad tank of gass . i had this motor installed 5 months ago it had 80 hours on it, i had the carb rebuilt when i had the motor installed

A quick test on fuel delivery is to have someone work the throttle while the boat is in neutral while someone simultaneously sprays a little carb spray into the spark arrestor/intake. If the RPM's pick up at all, you got carb issues. Any way you could pull a fuel sample to see what you have? Question of the day-- Has this motor/outdrive combo worked properly since the installation of the new to you motor?

yes i took it out twice and it ran well on the same tank of fuel.

Check all fuel CONNECTIONS and make sure they are tight...I was out on a boat recently that had just been repowered w/ twin 250s...idled well, but shove up the RPMs and the port motor would die every time...turns out the installing dealer used NON-SS hose clamps and in salt condition, two of them had already broken lose...

Also insure fuel VENT intake fitting and hose are clear all the way to the tank...bugs will nest in there...I posted pics here once when it happened to my 21...it'll allow enough air into the tank to idle, but powering up means more air draw and a partially blocked vent will shut 'er down...

does the engine still have points or is it HEi ignition? everyone has forgotten about points, if they set, they will need to be cleaned or replaced. 5 months is plenty of time for a carb to need to be rebuilt if it was left with untreated fuel

no the engine does not have points, and how would i go about testing the fuel, thanks to all who have replied this far

The easiest way to test it would be to not use it. Hook up a portable gas tank with brand new fuel in it. If she runs ok then it's a bad fuel problem...but I'm more inclined to go along with what Reel has said.. to me it sounds like she's starving for gas... I'd check all my fuel lines, fliters, etc. for cracks in the hoses, air leaks or obstructions. Do the simple things first... :head:

fuel
 

oki,that is what i.m going to do today check fuel lines , replace both filters i'll let you know how it went tonight, thanks again guys.