If you think hifi is expensive try this !!!!!!

[Audio Al]

One of my fleet of floating vessels has a problem

Its a 100hp Yamaha 4 stroke , It has developed a misfire rough running reluctant to rev up cleanly

This is a £11K engine now out of guarantee , As a former mechanic I have been through everything and am now down to too two 2 suspect electronics

3 weeks waiting list at 2 local Yam dealers

I asked for the prices of a TPS unit £220.00 and a CDI unit £1155.00 not asked for the price of the 2 dual outlet coils yet or a crank angle sensor I dread to think what the hourly labour rate is

The engine has done 19 hours from new

Wish me luck

[Light Dependant Resistor]

If its a hall effect type distributor they are fussy with the gap between the cam and the sensor.
Any water near them will cause a misfire. I would undo the distributor cap and use a hair dryer for a minute or two
to dry up any moisture, if there was chance that moisture was in there.

As for CDI units these are available as kits at reasonable prices.

[Pigmy Pony]

One of my fleet of floating vessels ( I have 6 ) has a problem

Its a 100hp Yamaha 4 stroke , It has developed a misfire rough running reluctant to rev up cleanly

This is a £11K engine now out of guarantee , As a former mechanic I have been through everything and am now down to too two 2 suspect electronics

3 weeks waiting list at 2 local Yam dealers

I asked for the prices of a TPS unit £220.00 and a CDI unit £1155.00 not asked for the price of the 2 dual outlet coils yet or a crank angle sensor I dread to think what the hourly labour rate is

The engine has done 19 hours from new

Wish me luck

Do you remember when you were a mechanic, and you had to give the customer a price for the repairs, remember that look on their faces? That's your face that is Seriously, I hope you get it sorted without too much pain.

My brother's had one or two boats over the years, and I know that financially hi fi is a piece of piss by comparison.

[Audio Al]

If its a hall effect type distributor they are fussy with the gap between the cam and the sensor.
Any water near them will cause a misfire. I would undo the distributor cap and use a hair dryer for a minute or two
to dry up any moisture, if there was chance that moisture was in there.

As for CDI units these are available as kits at reasonable prices.

Chris , this system does not have a distributor , it has a crank angle sensor , CDI , 2x coil packs , The only CDI unit I can find used is £250

[walpurgis]

Stale fuel in the tank left from last season?

[Light Dependant Resistor]

Chris , this system does not have a distributor , it has a crank angle sensor , CDI , 2x coil packs , The only CDI unit I can find used is £250

So likely to be either a hall effect or optical pick up sensor that needs checking. The CDI common circuit is explained here: https://www.youtube.com/watch?v=0yK3Opq_i0M
We can see the pulse rotor and trigger coil feeds to gate of a SCR ( Silicon controlled Rectifier aka Thyristor )

If you can check in your case the crank angle sensor that it is clear of any debris, which is the equivalent of the pulse rotor and coil in the above video.
There is a CDI kit available locally here: https://www.jaycar.co.nz/high-energy...n-kit/p/KC5513 if that might help.

I recall fixing a similar unit for a stranded motorist in remote Western Australia, the fault was a tiny amount of mud on the sensor - as soon as it was cleared
it ran like the proverbial kitten.

[AJSki2fly]

Stale fuel in the tank left from last season?

This is well worth checking and flushing the system through, if low grade fuel with ethanol was left in the system then after 90 days the ethanol will have separated from the petrol and the ethanol will then have absorbed water and chemically related creating a mild acid this, can/wll corrode quite a few components including rubber seals, this crap can get in the injectors etc. I know from experience as our mini Cooper S fuel pump diaphragm was turned in into a soft mess a few years ago and failed.

[spendorman]

"The engine has done 19 hours from new"

Perhaps you're covered under the Consumer Rights Act

[Audio Al]

Stale fuel in the tank left from last season?

No sadly not

[Audio Al]

This is well worth checking and flushing the system through, if low grade fuel with ethanol was left in the system then after 90 days the ethanol will have separated from the petrol and the ethanol will then have absorbed water and chemically related creating a mild acid this, can/wll corrode quite a few components including rubber seals, this crap can get in the injectors etc. I know from experience as our mini Cooper S fuel pump diaphragm was turned in into a soft mess a few years ago and failed.

Its a carb model and I have had the carbs off , they are spotless inside as they should be with only 19 hourd use from new , I allways pulled off the fuel pipe and left the engine running until it died , no more fuel left