120 hp Mercruiser 4 cylinder hard cold start

[JasonJ]

I have a friend whos boat has a horrible time starting when cold. Unsure of the year, but I think it is a late 80s early 90s 4 cylinder carbureted Mercuiser in a 15-16 foot ski type boat. Yesterday was my first time looking at it, he lives just down the inlet from me and I told him to leave it at my dock. I pumped the throttle a few times and eventually got it running after cranking it for a very long time. I suspect it has choke issues or is not getting any gas at first. He gets it going by pouring gas down the carb. Once running and warmed up, no problems. I have not actually put a wrench to it yet, I am hoping there are a few suggestions before I dive in that might save me some heartburn. The boat did sit for a few years prior to him buying it, but it is just the starting issue, otherwise it runs strong and smooth. Any suggestions before I dive in are much appreciated...

 

[lionhead]

Re: 120 hp Mercruiser 4 cylinder hard cold start

It would seem that the carb would benefit from a<br />good fuel tank additive that is designed to help get rid of gum and such from a long period of sitting.This is an inexpensive good move anyway even if it turns out there is some choke problem.

 

[Trent]

Re: 120 hp Mercruiser 4 cylinder hard cold start

If its a cold engine. Make sure the choke plate is almost closed before starting.

 

[StarLiner]

Re: 120 hp Mercruiser 4 cylinder hard cold start

I have a 1979 Renken with a Mercruiser 120. I am somewhat new to the boating world, 1.5 yrs with this my first one. Mine has a Rochester carb. I pump the carb a couple times and flip the choke manually. This usually gets her fired. If she sits for a month or so, I have to hit this trick. I am not a motor head. I am sure there is something that should trigger the choke vs manually. However, it works for me. The prior owner was not aware there was a choke. I guess he had good luck getting her going by just pumping and running the starter a while.<br /><br />Good luck

 

[trm]

Re: 120 hp Mercruiser 4 cylinder hard cold start

I had the same problem + in my 1968 Merc 120. A carb rebuild, new points fixed the problem ( and the + problems too).