wont start without some throttle

[Stevcool]

I just bought a deckboat Chaparral sunesta 220 1995 it was super clean. However it has sat since July. As expected had to pump throttle to get it to start first time. It runs fine idles fine in nueutral. I added gas additive to the 14 gallons to help old gas. Also added 4 fresh gallons. It ran on lake for 20 min all good. However when stopped went to start and won't unless half throttle in N. Starts revs high then you can pull back to middle again. Prior boat after running would start with key turn. Seller says had 31 point tune up last summer. Any ideas of problem. Has 5.0 v8 merc. Is it bad fuel filter or bad gas do I need to spray cleaner in Carb

Thanks

[Don S]

wont start without some throttle

Assuming it's a carbed engine, that's perfectly normal. It's not EFI.

[Stevcool]

It is Carb however I had a Carb 302 omc 1976 formula runabout before and it only needed throttle on first start after that key turn no extra throttle what is diffrent

[Don S]

It is Carb however I had a Carb 302 omc 1976 formula runabout before and it only needed throttle on first start after that key turn no extra throttle what is diffrent

Ok, you were lucky.

[riskibusiness]

mine is the same way. as I understand it some of this is due to the marine carbs routing all fumes and excess fuel back down the throat of the carb to avoid going boom. So its always slightly rich. Is that correct Don ? Cause thats my father in laws therory so if it is wrong it just gives me the pleasure of telling him "YOUR WRONG". lol

[dubs283]

as I understand it some of this is due to the marine carbs routing all fumes and excess fuel back down the throat of the carb to avoid going boom. So its always slightly rich.

what excess fuel??

if you have excess fuel causing a rich condition it is from a faulty carb setting, faulty fuel pump, or need of a carb rebuild

the reason you need throttle upon start-up is to set the choke and give the engine a little shot of fuel for start-up

if you need full open throttle upon start-up it is because the engine is flooded and there is an issue with the fuel delivery system

[Stevcool]

It never needs full throttle just about a forth of full then once started I can put at idle. Sounds like it is normal that is good. I just prefer the turn key start my edelbrock Carb had on old boat.

[Don S]

Depending on how long it sits, it could be the automatic choke is set too tight. When at idle position it would flood if the choke was fully closed and the engine still warm. I never adjust the automatic choke coils to Merc specs, they are always too tight. I normally take a cold engine (sitting overnight) give it maybe 1/8th throttle so the choke plate moves free. Then adjust the choke coil so the choke plate either just closes, or misses by 1/8" of closing.
It might make it better on warm starts, but you may also have to give it an extra pump when cold. Give it a try.

[Bond-o]

It never needs full throttle just about a forth of full then once started I can put at idle. Sounds like it is normal that is good. I just prefer the turn key start my edelbrock Carb had on old boat.

Ayuh,... So how long has it been since this motor was given a full, 'n complete Tune Up,..??

Fuel is only 1/4 of the equation that makes motors Run....

[Stevcool]

I will try checking the choke. I just bought it was told last summer had 31 point service not sure what they did I know oil was changed and impeller

[Don S]

was told last summer had 31 point service not sure what they did

Someone was paid money to point at your boat 31 times.

[etracer68]

In my experiance, all carb motors have differant personallites, generally because carbs, are not all created equail.