80hp 2 stroke problems

[BiggistBen]

Hey Guys,

New to this so cut me some slack. I have an older Mercury 80hp (5987606) two stroke. I bought the boat and the guy said he has not ran it in a while but it should start right up with a battery..... O Yeah right. So I did what I would do to anything that I believe that has been sitting for a while. Drained the gas, cleaned the tank completely while it was removed. Removed the carbs. making sure not to mess with the adjustment screws. Cleaned the carbs all the way, yes ever hole was cleaned with a pipe cleaner. All passages were open. Cleaned the fuel lines and fuel pump and the screens. So after all of that I put a batt. in and tried to fire it up. No luck. Adjusted the the throttle linkage to try to get it started in N. Still no luck finally moved throttle all the way forward and choked the you know what out of it. V -Room she fired up. Took out to the river and just put put put. Tried to open it up and every time it died. I thought well maybe the it needs adjusted more yup no luck. So I cleaned the carbs once again making sure everything was OK. Started it up tonight and it ran great with muffs on. Idled great and revved up great. Shut it off tried to start again and nothing. Felt like it was not getting any gas. So I thought well maybe the diaphragm is bad....maybe I missed something. Like an idiot I droped it and the dog grabed it and took off with it. Lets just say ones on order. With all of this being said do you all have any guesses why this thing will not run proper. Lost in WV

 

[1nebel0]

Re: 80hp 2 stroke problems

Fuel pump diaphram a must as Ethanol is horrible on rubber and gas lines...put a water separator on the boat if you don't have one given what Ethanol will do...Water is a 2 stroke's enemy and that is what Ethanol likes to attract. So far you have done what I would have done however you don't mention compression test which is the first thing that needs to be done...Next is to check for spark from all cylinders..If you are done a cylinder then comes the testing of the stator, trigger, coil, and lastly the most common problem with Merc's the switch box...Don' just buy parts as you won't like the costs and the lack of being able to return anyone of them...

 

[Chris1956]

Re: 80hp 2 stroke problems

It is very hard if not impossible to clean the carbs, w/o removing the idle mixture screw and blasting that passage. Sounds like you want to do that. It also likely makes sense to replace all gaskets and inspect or replace floats inlet needle and seats.

 

[GA_Boater]

Re: 80hp 2 stroke problems

Welcome aboard, Big. The reason your Merc won't run is because the dog ate the fuel pump. I bet you used that for homework too.

The good thing is you know the motor runs. I have to echo the others guys, tear the carbs apart, including the needle. If you haven't, order two carb kits and two floats for insurance. The carb kits tell you how to adjust the needles for start up and the fine tuning. No biggie. Also get a new impeller, I'm sure the old one is ancient.

While you're waiting check your compression and change the spark plugs. Come back with the compression readings. They should be with 10% of each other.

Finally, how to start the beast? First hook up the muffs, prime the fuel bulb until it's hard, lift the warm-up lever about straight up, gear shift in neutral, turn the key to on, hold the choke button and turn the key to start. As soon as the motor putts, release the choke. If it doesn't start right away, prime again and try it. Don't crank a long time because it's hard on the starter. When the motor is warm usually it will start with no choke or warm-up lever.

Good luck making that baby purr.