Mercury 3.5 HP Outboard Junk?

[Rustic Charm]

Originally Posted by Rustic Charm

I know this is an old thread but just in case anyone else is considering.

I've purchased a 3.5 and have done less than an hour on it. I've had it back to the shop once and the mechanic convinced me I'm using it wrong.

It stalls constantly, after ten minutes use, turn it off on the beach, try starting it again and it takes as many as 20 pulls to get it going. My wife can't get it going at all after a stint to the beach.

Power wise I don't think it is any better than the 2.5 Yamaha we had which was very reliable until I sunk it. And this 3.5 uses a hell of a lot of fuel for hardly going anywhere.

When I get home, I'll be taking it back for a refund. An outboard has to be reliable. This piece of **** is not.

Well, just to update on what I did with mine. All up it returned to the dealer four times. I had excuses from the manufacturer put the wrong fuel cap on it, to the fuel jets were the wrong size. On one occasion I put it down to stale fuel (3 months old) because they told me on the phone to put some fresh fuel into it and it was fine. But the next time I went to use it, it would take me a doz pulls to get it started.

So, last year I decided to simply buy a new Yamaha and I off loaded the Mercury. It would have had less than ten hours on it. Absolute piece of junk.

[Mike OReilly]

Mine still working fine. Takes extra throttle at start, and has a tendency to stall first off if given too much gas, but works fine so far.

[bensolomon]

Mine works fine, too. Just like Mike, above, she needs extra throttle at start. But....I was having the same issues as you, and put a new carb on and a new spark plug and, and my woes improved.

[a64pilot]

Originally Posted by Mike OReilly

Mine still working fine. Takes extra throttle at start, and has a tendency to stall first off if given too much gas, but works fine so far.

That is real common and indicative of a slightly lean mixture, and likely exactly as intended.

[Bermuda Forte]

I bought the Merc 3.5 thinking it was a small motor and my wife could start it. NG. Always difficult to start for me too. Several services and no better. I hear about the small jets. Then the linkage for the shift lever froze up. Expensive junk in my opinion. An old used Johnson 8HP 2-stroke purchased to replace it has proved very reliable.

[Mike OReilly]

Originally Posted by a64pilot

That is real common and indicative of a slightly lean mixture, and likely exactly as intended.

Thanks. Good to know. It's interesting the range of experiences this engine is producing. Poor quality control in the factory? I don't suppose there's any connection to which flavour the engine is branded? Tohatsu/Mercury/Nissan

[SV_Harbinger]

I have the tohatsu, same engine different stickers, and I'm rather pleased with it. When it's colder I do tend to need to use a little extra throttle when starting it and have to go gingerly release the choke or it will die, but once it's warm it gives no issues (takes about 5-10 minutes if the air temp is at or bellow freezing) And you absolutely have to run the carb dry if your not going to be using it for more than about a day. The carb uses really tiny Jets and they gum very easy and just like any small engine good, clean, fresh gas is very important.
I used to have a Lehr once apon a time, it is one of the only small engines I wouldn't recommend, not even as an anchor

[Pete7]

Originally Posted by Mike OReilly

Thanks. Good to know. It's interesting the range of experiences this engine is producing. Poor quality control in the factory? I don't suppose there's any connection to which flavour the engine is branded? Tohatsu/Mercury/Nissan

I don't think it's a QC problem, more as A64Pilot says, lean mixtures as manufacturers try to meat the latest emission standards which need tiny jets and weak mixtures. There is some evidence that in the UK fitting larger jets and on the little Suzukis helps no end, but we don't have petrol diluted with alcohol or other substances in Europe.

I have just swoped out a Johnson 3.5 2 stoke. bought new in 2005, never service until Jan 18 when the water pump finally stopped pumping. what a superb engine, money saved on servicing paid for the replacement Honda 2.3hp as you can't buy small 2 strokes in the UK anymore for leisure users.

Pete

[IdoraKeeper]

Just replaced the subject engine. Being of the age where coddling and cajoling small carburetted motors was a part of life, I didn't mind this engine. That said, nobody in my family except me could operate it. Eventually it began to stall under load. Testing indicated plugged Jets likely due to the effects of modern fuels. The solution was to replace the carburator.. However, they now make a 6hp motor that weighs nearly the same. The money went into a new motor. I traded off the 3.5hp for some skilled labor this winter. The new owner can justify the parts expense and I am sure he will get 5 more years of service out of the motor...I don't think you ever really wear one out. If you or your family lack an old fashioned intuition for gas, air and spark this motor will not serve your needs well. In the right hands it will last a very long time.

[Dockhead]

Originally Posted by IdoraKeeper

Just replaced the subject engine. Being of the age where coddling and cajoling small carburetted motors was a part of life, I didn't mind this engine. That said, nobody in my family except me could operate it. Eventually it began to stall under load. Testing indicated plugged Jets likely due to the effects of modern fuels. The solution was to replace the carburator.. However, they now make a 6hp motor that weighs nearly the same. The money went into a new motor. I traded off the 3.5hp for some skilled labor this winter. The new owner can justify the parts expense and I am sure he will get 5 more years of service out of the motor...I don't think you ever really wear one out. If you or your family lack an old fashioned intuition for gas, air and spark this motor will not serve your needs well. In the right hands it will last a very long time.

Hmmm. I thought Tohatsus, all of them, were supposed to work.


I bought one of this as an emergency replacement for a Selva 8 which could not be repaired in time for my summer cruise. The Mercury worked fine, although it was not particularly easy to start, and had a tendency to stall. But we used it all and the whole crew managed to deal with it, most of them not too mechanically inclined.



I'm now debating whether to sell it on and go back to the now-repaired Selva, or not, or to keep both of them. Hmmm.

[mikeod]

Bought one new in 2010. PITA! Carb needs cleaning if it sits for 2 weeks. Gas tank cracked while under warranty and took the dealer more than a month to get. Shifter is a common problem and you need to remove the power head to remove and grease it because they couldn't be bothered to install a 10 cent grease fitting. Needs to warm up a long time before it will run right. Not worth the expensive. BUY A USED 2 STROKE. I could come up with more.

[a64pilot]

Originally Posted by Mike OReilly

Thanks. Good to know. It's interesting the range of experiences this engine is producing. Poor quality control in the factory? I don't suppose there's any connection to which flavour the engine is branded? Tohatsu/Mercury/Nissan

I don’t think there is a lick of difference between different brand names other than stickers, they are all Tohatsu I believe.
However there may be differences between the same engine sold in different markets, it’s possible that an engine sold in the Bahamas may have different jets in the carb?

As one poster suggested, if you grew up say on a farm and are used to taking little motors apart and cleaning carburetors etc. you’ll have no problem with them, if your the type that pays someone else to do everything to any mechanical thing you own, you will, cause they seem to require frequent attention, all two strokes do, always have. This from a guy who grew up on two stroke motorcycles and raced a Husqvarna WR-250 in the mid 70’s.
Of course back then we ran either vegetable oil or bean (castor oil) which taught you how to disassemble and clean the carbon off of a motor.

If I had a newer small carburetor motor, I believe I’d get me a set of jet drills and drill out the Jets. Of course you have to know how to jet a motor and how to take plug readings.
I always jetted a two stroke as lean as it would smoothly run on the idle jet and as rich as it would smoothly run on the main jet.
Reason is lean on idle is to prevent loading up and Rich at high power to keep it cool and help prevent seizure, always a problem on high performance air cooled two strokes.

My fuel injected Suzuki is brilliant, always runs perfectly. Perhaps fuel injection will trickle down to smaller motors?

[Group9]

We had a Mercury (Tohatsu) 3.5 hp. 2 stroke for several years. It never let us down and I only threw it in with the sale of our last sailboat at the buyers request. I wish we still had it.

[Mike OReilly]

Thanks again a64. Just to be clear though, my Tohatsu is a 4-stroke, 3.5 hp. I've now owned it for at least five years and have never had to clean the carb, or indeed do anything other than change the oil.

Now, I don't put a lot of hours on the engine, and I now only use premium gas (didn't for the first cole of years though). I run it dry when it won't be used for a while. But honestly, other than upping the starting throttle, and feathering the gas for the first 10 seconds, I've had no issues whatsoever.

I'm beginning to feel very lucky ... and now expecting this to change [emoji6]

[a64pilot]

What is most likely keeping your engine trouble free, is your running it dry before you put it away.
Premium is fine, but isn’t any less likely to contain ETH in most States, although some do allow Premium to be alcohol free, depends on of course where you buy it.
What is interesting is you don’t seem to hear the carburetor horror stories about the little Honda generators, and those except for the new ones are difficult to run dry.
I drain the carb on mine, but doubt most do.

Carburetor wise, the four stroke is likely to be more problematic than a two stroke, carb and jets seem smaller and presumably the oil in the fuel on a two stroke likely acts to preserve the fuel to some extent, I know some of the oils advertise that they have fuel preservative in them