15hp Enduro running rich

[mikedefieslife]

A friend of mine bought a new 15hp Yamaha Enduro. e15dmhs.

It is constantly running rich and fouling plugs every hour or two of running.

He's mixing 75:1 (the manual calls for either 50:1 or 100:1 depending on where you read it).

The main jet is #108, this is standard as shown in the parts fiche. I notice the standard non-enduro runs a #110 jet, however, if the engine is running rich, then one would normally need to a smaller jet.

Anyone else got experience with the 15hp Endruo? Unlike other Yamahas there isn't much information about them online, despite them being on the best selling small outboard around.

[TownsendsFJR1300]

I'm not sure where your fuel pump is but it's not un-common for it to leak fuel (worn out diaphram) into the engine and run SUPER RICH...

Sometimes priming the bulb will show leakage at the pump... I'd be checking the pump myself..

Re-reading, this is a BRAND NEW ENGINE???

.

[mikedefieslife]

I'm not sure where your fuel pump is but it's not un-common for it to leak fuel (worn out diaphram) into the engine and run SUPER RICH...

Sometimes priming the bulb will show leakage at the pump... I'd be checking the pump myself..

Re-reading, this is a BRAND NEW ENGINE???

.

Well brand new as in bought in around March, so will have a good 30 hours on it now.


EDIT: I see you meant the primer bulb.

[TownsendsFJR1300]

I'd be visiting the dealer myself...

[mikedefieslife]

Yeah, the engine was bought in Martinique. It is now in Bonaire. The Yamaha dealer in Bonaire doesn't want anything to do with it.

The joys of cruising around the world huh?!

[boscoe99]

What is the engine serial number?

Try using Pennzoil 100% synthetic oil and see what happens. Some folks are amazed as to how it can cure plug fouling.

[TownsendsFJR1300]

Not related, but Bonaire is about the nicest place for scuba diving in the world... (I'm jealous...)

Was there twice, years ago. Would love to go back...

Good luck with your issue...

[99yam40]

brand new motor, has he followed the break in for the new motor to set rings / cylinders ?
think premix motors used extra oil on break in , but since I have never bought a new on I cannot say for sure

does this motor have a choke or a prime start system?

[robert graham]

What is the engine serial number?

Try using Pennzoil 100% synthetic oil and see what happens. Some folks are amazed as to how it can cure plug fouling.

I don't think they still make the 100% synthetic.....I used it for years myself and can't find it anywhere....Same story with the Sierra 100% synthetic...just can't find it anymore....

[boscoe99]

If you can't find 100% synthetic Pennzoil then try a blended synthetic. In any brand that is not Yamalube. For some reasons unknown to me, Yamalube will foul plugs in some Yamaha models whereas other brands won't. Strange that, but it has been seen to be true on multiple occasions. May or may not work for your motor. Can't hurt to give it a try.

[boscoe99]

I don't think they still make the 100% synthetic.....I used it for years myself and can't find it anywhere....Same story with the Sierra 100% synthetic...just can't find it anymore....

As there are less and less two strokes out in the world there may be less and less availability of two stroke oil brands and types. Not enough demand to justify production.

We can always return to the days of yesteryear when simple motor oil was mixed with gasoline.

[robert graham]

As there are less and less two strokes out in the world there may be less and less availability of two stroke oil brands and types. Not enough demand to justify production.

We can always return to the days of yesteryear when simple motor oil was mixed with gasoline.

I understand that, running a C90 premix Yamaha....Last oil I bought was some Quicksilver synthetic blend...have to wait and see how it does. Actually plug fouling has never been a problem for me so far....the cloud of smoke at morning start up helps with mosquitoes....