Johnson GT 150 1988 model..... been sitting for quite some time

[ffountain]

This engine has been sitting for 3 years without being run. Aside from draining the tank and putting in new fuel, what else should I do? Would it be best to take it to the shop and have the carbs cleaned?

 

[emdsapmgr]

Re: Johnson GT 150 1988 model..... been sitting for quite some time

The enemy of a stored engine could be any dried fuel that may be inside the carbs. This fuel gel, once dried, clogs fuel passages and jets so that the engine won't run properly. Probably best to just try to start it and see how it runs. If the engine was properly put away for long-term storage, it could be just fine. You'll know a soon as you start it. Good idea to toss the old fuel-complely drain the tank. I'd suggest you also change the lower unit gear oil. Once started, check the telltale closely. Possible the water pump impeller is weak. If you don't know the last time it was replaced-change it before you start it up. Once running, check the cyl head temps with a laser temp gun. Should idle between 143 and 155 degrees when sitting on the trailer. This will tell you if the two thermostats are working.

 

[ffountain]

Re: Johnson GT 150 1988 model..... been sitting for quite some time

The enemy of a stored engine could be any dried fuel that may be inside the carbs. This fuel gel, once dried, clogs fuel passages and jets so that the engine won't run properly. Probably best to just try to start it and see how it runs. If the engine was properly put away for long-term storage, it could be just fine. You'll know a soon as you start it. Good idea to toss the old fuel-complely drain the tank. I'd suggest you also change the lower unit gear oil. Once started, check the telltale closely. Possible the water pump impeller is weak. If you don't know the last time it was replaced-change it before you start it up. Once running, check the cyl head temps with a laser temp gun. Should idle between 143 and 155 degrees when sitting on the trailer. This will tell you if the two thermostats are working.

I guess my biggest concern with starting the engine is running a cylinder dry and having major repairs to make. Will the temps taken with a lazer temp gun tell me if it's getting fuel and oil to the cylinders before dammage is done?

 

[guitman32]

Re: Johnson GT 150 1988 model..... been sitting for quite some time

I think if one cylinder was running dry youd probably know it well before you did any catastrophic damage like that...like when you first start it.

Either way after 3 years sitting a carb cleaning would probably be in order...these carbs are very simple, really no adjustment just cleaning out the orifices and jets. When you rebuild, just make sure everything seals as it should and that the float is level.

Do you know if the engine works? Have you turned it over to check spark/compression? You can do all that without starting it.

 

[emdsapmgr]

Re: Johnson GT 150 1988 model..... been sitting for quite some time

You can always try to start the engine and let it idle. After a few seconds, shut it off and pull the plugs out. If all 6 plugs are dark/wet then they are getting fuel. If you just aren't sure, before you start it, pull the carbs apart for cleaning. I'd pull all the jets out and visually inspect them to be sure they are not restricted. Agree with guitman, the carbs on that engine are pretty simple.

 

[ffountain]

Re: Johnson GT 150 1988 model..... been sitting for quite some time

Do you know if the engine works? Have you turned it over to check spark/compression? You can do all that without starting it.

Yes, the engine works. It was running fine when I parked it but I did nothing to it for an extended period of storage. I typically used it at least once a month. I started working on another boat and began using it because it was cheaper to haul and used less gas.