2.5hp yahama 4stroke outboard problem

[duke]

HI All,

I haven't used this outboard for two seasons and left some fuel in the integral tank.

Had problem starting so brought it to service agent.

The stale petrol caused a blockage in the carburettor ( seems fuel passage is very small
In this size engine).
Am advised it needs a new carburettor costing approx £275.

The engine will run at start setting but cuts out at any increase of throttle.

Is there any additive I can use in the fuel that might? clear/clean the fuel passage to some degree?
All advice much appreciated,
Duke.

 

[VicS]

rather surprised if it cannot be dismantled and cleaned!
Sounds as though the main jet may be blocked.

Carb cleaner is available in aerosols BUT may not be suitable if any parts are plastic.

Diagram of carb HERE

 

[Ripster]

I bought a Mariner that had the same problem, started but would not rev. But stripping the carb, cleaning thoroughly sorted it out. Just pull the carb apart and clean out the old fuel sediment. It will be a yellow/brown deposit and will be blocking all the capillaries and jets. You do need to do ALL the holes, main, float, pilot etc. Also, on mine I had deposits on the in-line fuel filter too between the tap and carb, so clean all the supply pipes/tap too. Should run OK after that. It took me two goes to get everything, but now it runs fine.

 

[robertj]

a good friend of mine had the same problem, he kept getting dirt and water some how in the fuel, this is even after very careful decanting through fine funnel filter.
He fitted an inline filter for about £6 i think and this cured all, no problems at all.

 

[duke]

2.5 yamaha 4stroke outboard problem

Thanks for all replies,
Duke.

 

[geepee]

I had same/similar problem this year with a 2.5hp Johnson
Started every time but cut out when opening throttle but ok if left on tick over for 2-3 minutes
Couldn't find a mixture adjustment screw on the carb so phoned the dealer who said this was very common - apparently they are set to run very lean to meet emmissions standards
There was a mixture adjustment screw but it was covered by an 'anti-tamper' metal disc, pressed into the hole above the adjustment screw
10 seconds to drill through the disc and 2 seconds for 1 turn anticlockwise on the screw
Runs perfectly now

 

[duke]

2.5 hp 4stroke yahama

Thanks for that new response,

Duke.

 

[ccmarti]

You said : There was a mixture adjustment screw but it was covered by an 'anti-tamper' metal disc, pressed into the hole above the adjustment screw
10 seconds to drill through the disc and 2 seconds for 1 turn anticlockwise on the screw
Runs perfectly now.
Can you say where I have to bore and find the adjustment screw?