80HP Mercury Mariner BOGS

Well 1st time out this year and while the engine was working perfect last year, it seems to have an unusal problem.

Ofcourse nothing showed up with the muffs on yesterday. Started right up and reved nice.

In the water, under load it starts right up, although needs to be choked even when hot, and idles nicely.

As I bring down the starting lever and give it gas it stalls sounding like it is starving fuel, everytime.

However, if I push the throttle forward with starting lever up, and slowly bring the starting lever down, I can get the engine to rev up and it goes likes fantastic. Great top end good at slow speed, PERFECT.

The fuel diaphram is new and is good condition. The check valves look like the originals.

Weather is great here in East TN and I would like a good boating season, can anyone help?

Re: 80HP Mercury Mariner BOGS

With the idle lever up the throttle plates are slightly open, drawing a portion of fuel thru the main jets, and keeping the engine alive.

Careful touches of the choke could accomplish the same thing.

The idle jets are dirty, gummed up, and restricting fuel flow to the point that the motor will not idle without an addition source of fuel.

It is time to clean your carbs.

Re: 80HP Mercury Mariner BOGS

Well I failed to say that I let the boat sit for a 3 months without "running the fuel out of the carb" and I know something is clogged from dried gas.

The problem really happens when I try to accelerate. I guess you are saying that the clogged Idle jet is not "carrying" the motor over to where it can "suck" gas thru the main jets?

I am thinking of adding some Sea-Foam cleaner to 6 gallons and running the boat at various speeds and hope the cleaner gets to the clog. If that don't work I will probably need to go to a shop and have them soak the carbs.

Have you heard where this would work??

Re: 80HP Mercury Mariner BOGS

Either the fuel pump diaphragm has seen it's day, or the carbs need cleaning. Hit it from both ends....spray Deepcreep in the carb throat while slightly revved and dump a can in the fuel. On my merc, I fill the fuel bowl up with seafoam and pump the bulb. Smokes like Cheech and Chong, but it gets the job done.

Next time, use Stabil and Seafoam to treat the fuel.

Re: 80HP Mercury Mariner BOGS

Well ran about 3 gallons of gas with 8ounces of Sea Foam at various speeds and idle and did nothing, nada.

I will try the "a bowl full" and see how that works.

Out of curiosity on a 80hp Mercury Mariner carb is the idle jet accessible from the side, once the bowl is off?

I could try to see if a tiny wire will go thru??

Thanks to all!

Re: 80HP Mercury Mariner BOGS

I have seen it frequently suggested by others in this forum that removal and soaking in a gallon can of carb cleaner is the only/best way to get a gummed up carb clean. Using spray carb cleaner is often not sufficent to get the internal passages clear and while SeaFoam added to fuel is great for keeping gum build-up from occuring, it may not sufficently remove existing deposits. Also, poking around the jets with a wire may not be a good idea either.

Just my thoughts.

Re: 80HP Mercury Mariner BOGS

I think your right. They sell that a 1 gallon can for like $20 at the local advanced auto store.

Re: 80HP Mercury Mariner BOGS

Hey there, is there any "trick" to removing and soaking the carbs so as not to require re-adjustment.

Also, what things would be necessary to soak and clean them right such as removing the boawl, blowing out passages with air, etc?????

Re: 80HP Mercury Mariner BOGS

When it comes to any tricks, I do not remove the fixed jets (as I do not want to damage them if they are stuck) or the throttle plate from the throttle shaft (as I do not want to have to reallign the plate when reinstalled) when soaking the carb body. I figure this is OK as these are metal parts too. Regarding the linkages connected to the carbs, I always follow the link and sync instructions to make sure linkages are adjusted correctly. Others may have different opinions on this.

It is also good to get a Mercury shop manual, as it will have step by step instructions.