3.0 litre merc hard to start when cold ??

[Gods Favor VIP 1800]

Our 3.0 litre mercruiser (GMC 181) Is very hard to get started when cold.
If the boat has sat for say 2 weeks and you try to start it by the manual's
directions for cold starting it will stumble repeatedly. usually a large amount
of throttle has to be applied to get her to clear her throat. once running it's
fine. out on the water -fine . Just getting her to fire up easily cold is a problem. Could my choke be mis adjusted? Or not working properly?
Or worse ? How Can I check it out ?
I think it's the mercarb model?

Gods Favor VIP 1800

 

[Haut Medoc]

Re: 3.0 litre merc hard to start when cold ??

Pull the flame arrestor off when cold, pump the throttle & the choke plate should almost close.....​

 

[Gods Favor VIP 1800]

Re: 3.0 litre merc hard to start when cold ??

I had checked that butterfly position. It looks just like you said almost all the way closed. If I have not run the engine in several weeks it is a bear to start.
I push throttle to wide open 1 time and back to 1/8 to 1/4 open. When I hit the key it wants to stumble but not start up. If I open the throttle more while trying
to crank it will finally start but it gurgles allot before clearing out. Then all is fine. Idle is good . If I shut it off and try to start it again it fires right up.
Could it be I'm not priming enough before attempting to start for the first time.
Or the carb is in need of some work, adjustment, etc.?
The idle in neutral on the bunny ears is just above 1000 is this too high/low?
When we had it out the last time it acted like it want to stall at slow speeds
in gear.

Gods Favor VIP 1800

 

[Haut Medoc]

Re: 3.0 litre merc hard to start when cold ??

I had checked that butterfly position. It looks just like you said almost all the way closed. If I have not run the engine in several weeks it is a bear to start.
I push throttle to wide open 1 time and back to 1/8 to 1/4 open. When I hit the key it wants to stumble but not start up. If I open the throttle more while trying
to crank it will finally start but it gurgles allot before clearing out. Then all is fine. Idle is good . If I shut it off and try to start it again it fires right up.
Could it be I'm not priming enough before attempting to start for the first time.
I'd try two pumps.....
Or the carb is in need of some work, adjustment, etc.?
The idle in neutral on the bunny ears is just above 1000 is this too high/low?
Too high.....
When we had it out the last time it acted like it want to stall at slow speeds
in gear.

Gods Favor VIP 1800

What is the rpm reading idle, in gear?.....
You should verify your tach......

 

[antsmands]

Re: 3.0 litre merc hard to start when cold ??

Hello Gods VIP 1800;

I have the same exact problem with my 3.0 MCM as you described and I am going to rebuild my carb for next season. You may also want to do a compression test. 1000 idle speed seems high from what I have read in the repair manual and on this forum. I should be between 600-700. If you have good compression and ignition a carb rebuilt should help.

antsmands
Sea Sprite Mark V, 3.0L Mercrusier

 

[Gods Favor VIP 1800]

Re: 3.0 litre merc hard to start when cold ??

I only have a problem when starting from cold ! Other than that all is great!
Boat runs out excellent. No problems at all once underway. My tach may be
telling me a high reading. I will have to check the idle/in gear rpm's. Right now
I do not know the figure. I assume you meant when in the water in gear idling along? But, you are right if my tach is incorrect i can't use it for adjustment.
Could it be a leak at the base gasket (between carb and manifold?)


Lots to check!!!