Merc 50hp 4-stroke stalling

[Poke-Eye]

A good friend of mine has a 1995 50hp 4-stroke Mercury. Since it was new it's had problems dying while idleing. This can happen 5 to 25 times a day. Needless to say this is really p*%%*ng him off. He mostly drift fishes, leaving the motor idle (for maybe 10 minutes at a time) to bump in and out to stay on structure. Claims he has talked to the dealer. Says they told him not to idle so much and basically told him to live with it. They must think it's loading up.

I thought it was something he was doing, so we switched boats for a day. He wasn't wrong! Made for a long day to say the least! That evening we changed the fuel filter and plugs. Also drained the carbs. Thought I was going to lose it trying to get at the bottom plug! Took it out the next day for a test run and it didn't make any difference.

We talked to a Mercury mechanic about it this fall in Canada. He didn't know for sure if this was the correct year, (as we were on the water at the time), but informed us Mercury has had this problem. He claims the intake manifold could have a metal shaving in one of the passageways. Says this happened at the manufacturing plant that made the manifold for Mercury before assembly. In his words "there are a million & one passageways in them". His suggestion was to have the local dealer try putting a new one on when we got home. I think he was honest and not trying to drum up business.

My question is this: Has anyone else out there had this problem and if you did how did you fix it. Would also appreciate any info regaurding TSB's on this subject.

Other than this one problem this is one sweet motor! Burns almost half the fuel as my 40hp classic. Quiet and smells better too!!

As if you folks don't already know it, this message board has the others beat, HANDS DOWN! Keep it up!

[Pipestone Angler]

I to am interested in this very same subject. Ended up trading mine for a 60. No problems yet.

[Gearhead]

I would suspect a vacuum leak leaning out the fuel mixture. I too have had a metal shaving in a spot it wasn't supposed to be, but it was on a gasket surface between the intake manifold and the cylinder head. This caused it to suck air past the foreign metal because the gasket could not seal properly at that location. I found it by using spray carb cleaner. Using the straw, and a delicate finger,....just get it to spit cleaner out of the straw. First spray into the throat of the carb, and if the rpms stabilize and eliminate the harse idle, then the mixture is lean. Do not use the spray full blast as you're just trying to make up for the fuel deficiency that the added air from the vacuum leak is causing. With the spray, follow all gasketed surfaces that pertain to fuel intake. If the rpm of the motor goes up, you've found a vacuum leak. My 15hp 4stroke Evinrude had a split rubber plug on a vacuum T that was causing a similar idle problem last year. I found it using this same method and replaced the plug for under a buck! Hope this helps some.

[Poke-Eye]

Thanks for the tip! Won't be able to try for a couple weeks as my buddy is out of town. I'll keep you posted.

[Bob]

The first years of the 4 stroke 50's had some carb problems that seem incurable. In the spring and fall when the water got cold the auto choke would not work properly. If you want to email me bob@pinewoodsports.com I can see if there is any info I can dig up for you. The 60 HP is a great engine and has no issues with it.