Yamaha 2a 2hp outboard starts but dies

[Hoist]

Little Yamaha 2hp 2A outboard

Starts up fine on choke but quickly dies

Within 5 seconds

Carb been apart, no signs of junk and everything seems normal.

Took fuel off and opened tap flows out perfectly. Fuel is also fresh

Any ideas? These things are so simple that I’m stumped

Cheers

 

[Poignard]

Tank air vent?

Although I would expect it to run for more than 5sec

 

[Mark-1]

Little Yamaha 2hp 2A outboard

Starts up fine on choke but quickly dies

Within 5 seconds

Carb been apart, no signs of junk and everything seems normal.

Took fuel off and opened tap flows out perfectly. Fuel is also fresh

Any ideas? These things are so simple that I’m stumped

Cheers

Float height?

 

[OCuea]

Little Yamaha 2hp 2A outboard

Starts up fine on choke but quickly dies

Within 5 seconds

Carb been apart, no signs of junk and everything seems normal.

Took fuel off and opened tap flows out perfectly. Fuel is also fresh

Any ideas? These things are so simple that I’m stumped

Cheers

Dies on choke or choke open by then?

 

[RivalRedwing]

Change the spark plug? easy check, might as well do it

 

[OCuea]

Change the spark plug? easy check, might as well do it

I am no expert but I bought the same or similar engine as spares or repair 30 maybe years ago. I just checked it had spark, compression and carb and throttle and choke looked ok and handed over £20. I then spent at least 3x as much on carb kit and so on and enjoyed a shed maintenance. Worked like a dream and sold for a nice profit when I didn’t need it any longer

 

[johnalison]

I'm not going to give an engineering answer, but a while ago I had a similar problem and it was solved by using fresh petrol.

 

[Poignard]

I'm not going to give an engineering answer, but a while ago I had a similar problem and it was solved by using fresh petrol.

Good thought but he said the fuel was fresh.

 

[DownWest]

I was given one a while back after a couple of people had tried to sort it. On first check it had no spark, but everything seemed to be OK? By chance, while checking the plug cap, I found that the inner wire had retracted from the screw that makes the contact. Shortened the outer casing and remade the connection. Works fine, except I have no use for it..
OK, not the OPs problem, that has to be fuel/carb related.
I have just revived a 30 yr old Honda Genset with a carb off Amazon. €25....

 

[Rappey]

Carb. Usually involves taking it off, cleaning then putting back on. By the 3rd or 4th refit it usually starts working.
Put in a new plug as they can fail under load

 

[Boater Sam]

Carb blocked somewhere certainly. There are tiny drillings in the aluminium, all of which matter as well as the jets holes

 

[OCuea]

I believe the electrics on the Yamaha are bullet proof, so I would go with carb too …. especially look at jet….. a can of carb cleaner is so satisfying and it cleans the heck off of virtually anything …. Much stronger than brake cleaner. I would mention I had a similar problem on an old 2 cylinder evinrude that was like new but stored for many many years and it had what looked like a complicated electrical system to me, so I was lost and gave up. It sits in a friend’s shed to this day. It would be mint if it worked and if I had not misplaced the lower plastic cowling …. I am useless at keeping all parts together when I disassemble …. or I used to be …. (probably carb trouble if not the electrical system that I could not figure out ….. because the bowl of carb was solid gum or varnish - so many years ago before I know what I know now - maybe I did not clean carb long enough or properly enough.

 

[Hoist]

Fuel tank vent was open.

Fresh fuel

Fuel flow checked from tank

Admittadly this engine is about 3 engines made into 1.

I have been using a 2hp yamaha since I was 4 years old and now 39 so I feel I know them inside out.

The starting process is definately down pat.

I am certainly thinking float height. The brass arms look a bit janky

Inside the carb was perfectly clean and serviceable in my eyes, and i have checked the float doesnt emit bubbles when submerged.

Also check that the needle and seat was working with the old blow test. Still tastes bad!

Someone is selling copy carbs on ebay for 23 quid. the service kit is 35 so I am going to gamble on china

 

[garymalmgren]

Fuel.
Condition = new.
Flow, Getting to the carb = OK.
getting to the start /idle jet = OK
= Engine should idle.
(Starts up fine on choke but quickly dies) Engine doesn't idle.
Restriction or total cut off of fuel flow = blockage. Clean jets.

You have been through all of these steps.

Electrics
Condition = coil, plug, plug cap , wiring.
Operation = enough spark to start.
Then Starts up fine on choke but quickly dies
As you have been over fuel again and again, it is time to look elsewhere.
I would disconnect every wire (plug or screwed earth) inspect and reconnect.

 

[PetiteFleur]

I now always use E5 premium petrol + Honda additive for my lawnmower, Honda 2.3, 2T strimmer & small generator. Makes a big difference as E10 petrol goes stale quickly. My Honda 2.3 started 3rd pull three days ago after winter layup. Works for me.

 

[Poignard]

I remember I had a similar problem caused by dirt in the fuel tank partially blocking the filter.

Enough fuel could seep through the filter to fill the carburettor bowl so the engine could start, but not enough to keep it running once that had been used.

 

[Poignard]

I remember I had a similar problem caused by dirt in the fuel tank partially blocking the filter.

Enough fuel could seep through the filter to fill the carburettor bowl so the engine could start, but not enough to keep it running once that had been used.

Better forget that.

I have just noticed that the OP wrote:

"Took fuel off and opened tap flows out perfectly.".

 

[Mark-1]

Better forget that.

I have just noticed that the OP wrote:

"Took fuel off and opened tap flows out perfectly.".

Yeah, but the idea is a good one. Maybe such a blockage is just further down stream than was checked.

A new carb will narrow it down at the very least. Even if the Chinese carb is rubbish the symptoms will change if the problem lies in the carb. (I just bought a Chinese carb for my chainsaw from LandS. Didn't like buying after market but it worked and the carb was cheaper than the OEM diaphragms. So Chinese after market carbs can work.)

 

[CJTurner]

Coil. Hard to find. (Or I found that..). Will it run on easystart spray?

 

[Hoist]

Tried again today.

Spark nice bright white spark

Also got a couple of belts trying to see it in the sunlight

Carb went through a serious cleaning regime last night

Didn't even try to start today.

Took the carb off to check fuel was in the bowl and it looked perfect and up to level.

Only thing I didnt have was a plug. The old one is rusty on the outside but seems to have the normal running brownish color when taken out.

Had enough of it for today.

£50 ono