Puzzled - Yamaha 2HP 2 stroke won't start.

[ThreeSummers]

I was recently given an old (15 years?) Mariner badged Yamaha and have finally got round to seeing if it will run. No go.

I tried starting it this morning, but nothing happened - okay, so it's been standing for quite a few years without use, what else would I expect? So, as an easy option sprayed some carb cleaner into the air intake and, well, it runs on that!! Each time I spray, pull cord and it instantly fires for about a second (burning the carb cleaner I guess).

So, I assume it's not getting fuel - take off carb; everything looks fine, needle moves, jet may have been blocked - though I cleaned it with a wooden toothpick and only oily residue there from the fuel. Fuel line clear too. But I've only taken the float bowl off so far - I don't want to mess with the needle assembly if I don't have to.

Anyone have any ideas why this thing won't burn petrol?

BTW, when checking the spark plug it was hand tight and had never been tightened - compression ring not deformed. Totally clean too. Top of the piston is shiny and silver. Carb is totally clean inside and out. No soot in the exhaust - I honestly think this motor has never been used before!

Regards,

Tim.

 

[TimfromMersea]

I was recently given an old (15 years?) Mariner badged Yamaha and have finally got round to seeing if it will run. No go.

I tried starting it this morning, but nothing happened - okay, so it's been standing for quite a few years without use, what else would I expect? So, as an easy option sprayed some carb cleaner into the air intake and, well, it runs on that!! Each time I spray, pull cord and it instantly fires for about a second (burning the carb cleaner I guess).

So, I assume it's not getting fuel - take off carb; everything looks fine, needle moves, jet may have been blocked - though I cleaned it with a wooden toothpick and only oily residue there from the fuel. Fuel line clear too. But I've only taken the float bowl off so far - I don't want to mess with the needle assembly if I don't have to.

Anyone have any ideas why this thing won't burn petrol?

BTW, when checking the spark plug it was hand tight and had never been tightened - compression ring not deformed. Totally clean too. Top of the piston is shiny and silver. Carb is totally clean inside and out. No soot in the exhaust - I honestly think this motor has never been used before!

Regards,

Tim.

Is the fuel switch on lever (mid right of the motor as you look at it to pull the starter cord) actually turning the fuel op, or just turning on it's axle? And after that, is the air vent on the tank filler blocked (try to start it with the fuel cap off)

 

[Tony Cross]

Take the main jet out, I bet it's gummed up with old petrol. The carb cleaner burns because it's already atomised but if the main jet is fouled up it can't atomise the petrol.

 

[TonyBuckley]

There seems to be an awful lot of problems with outboards at the moment!

 

[ThreeSummers]

Is the fuel switch on lever (mid right of the motor as you look at it to pull the starter cord) actually turning the fuel op, or just turning on it's axle? And after that, is the air vent on the tank filler blocked (try to start it with the fuel cap off)

I'd say so - the float bowl was full. Also, with the fuel line removed from the carb, it flows freely when turned on. Will check the vent.

Take the main jet out, I bet it's gummed up with old petrol. The carb cleaner burns because it's already atomised but if the main jet is fouled up it can't atomise the petrol.

I can blow air though there (yuck, hate the taste of petrol) but the pressure doesn't change when I pull the throttle up (I guess that's controlled on the other jet?)

Tim.

 

[silverdawn]

I have a 3.3 hp Mariner wouldnt start, new plug/new fuel /cleaned carb then discovered an in line fuel filter on the end of the fuel line inside the tank this was completely blocked , cleaned it and the engine started first, pull and has been no trouble since, perhaps you have a similar set up?

I was recently given an old (15 years?) Mariner badged Yamaha and have finally got round to seeing if it will run. No go.

I tried starting it this morning, but nothing happened - okay, so it's been standing for quite a few years without use, what else would I expect? So, as an easy option sprayed some carb cleaner into the air intake and, well, it runs on that!! Each time I spray, pull cord and it instantly fires for about a second (burning the carb cleaner I guess).

So, I assume it's not getting fuel - take off carb; everything looks fine, needle moves, jet may have been blocked - though I cleaned it with a wooden toothpick and only oily residue there from the fuel. Fuel line clear too. But I've only taken the float bowl off so far - I don't want to mess with the needle assembly if I don't have to.

Anyone have any ideas why this thing won't burn petrol?

BTW, when checking the spark plug it was hand tight and had never been tightened - compression ring not deformed. Totally clean too. Top of the piston is shiny and silver. Carb is totally clean inside and out. No soot in the exhaust - I honestly think this motor has never been used before!

Regards,

Tim.

 

[Lakesailor]

Blow through the dismantled carb both ways with an air line. Are you sure the needle valve isn't stuck? If the fuel doesn't reach the correct level the venturi effect won't pull fuel through the main jet.
Will it start with petrol, not carb cleaner, squirted into the carb throat?
Does the plug get wet at all?
If it's not been used much during all that time perhaps the reed valve in the crankcase has gummed up, either closed, or open.

 

[TQA]

If it is old petrol oil mix [ 1 yr + ]that may be the problem.

Try some fresh.

 

[ThreeSummers]

If it's not been used much during all that time perhaps the reed valve in the crankcase has gummed up, either closed, or open.

Reed valve is spotless - as I mentioned earlier, I don't think this motor has ever been run. Innards of carb all clean and dry (apart from 2S oil as you'd expect), no gum or residue anywhere at all.

50:1 mix btw.

50:1 is what I have - will reassemble and try again tomorrow and see if the plug is getting wet.

Will let you know how I get on.

Tim.

 

[dartmoor]

There seems to be an awful lot of problems with outboards at the moment!

Must admit, that's why I start my outboards about once a month all the year round - seems to keep things going.

 

[nigelmercier]

If it is old petrol oil mix [ 1 yr + ]that may be the problem. Try some fresh.

+1

I now use Fuel Fit stabiliser on all my occasionally used petrol engines: http://amzn.to/1jpCxR5

 

[ThreeSummers]

Well, I guess it could have been any of the above mentioned ideas...

Cleaned everything, poked jets, checked tank vent (needed to open 3 full turns for air flow) reassembled and gave it a new mixture of fuel (does oil go off? My original mix was old oil)

Started on the third pull and half emptied my water barrel in about 5 seconds - no neutral. Now to clamp it on a boat and see how it goes. Then I start on the 5hp that also hasn't been used for a long time.

Thanks everyone,

Tim.

 

[ThreeSummers]

I've been doing some googling and found a list of serial numbers that shows this little motor to be an '89 model - 1990 is the last year of listing.

Propeller shows scuff marks on the outer edges that could have come from 25 years worth of being moved around a garage but having seen the insides am still convinced that it's never been run.

Time to check impellers and seals I guess.

Then, I think I'll follow the running in procedure just to be safe.

Interestingly when I got this motor I also got a 2001 Yamaha 5hp, with sales receipt and manual etc. The manual covers 2/3/4/5 hp models and the 2hp shown in there is identical in every respect to this "Mariner" of 12 years before.

I know the guy that gave them to me never ran the 2 as he bought the 5 when he was given the motor and a boat by his friend - but unfortunately his friend recently passed away so we can't find out any more. Incidentally, it was due to the fact that they were originally given to him that he decided to give them away when he no longer had use for the boat. All he asks is that I take him out fishing sometime...

I wonder if it will last another 25 years.

Tim.

 

[dartmoor]

Great engine Yamaha 2HP - superb power to weight ratio as it weights just around 10 kilos. Numerous Chinese copies of it exist now - the Parsun one is an identical copy. No doubt not quite up to Yamaha's original though.

Yamaha 2B is everything a small outboard should be - unsurpassed for practicality in my view.