Yamaha 150 Four Stroke unstable tickover

Pipster100 · 30 March 2019, 18:32

Hi All,

I'm hoping someone can maybe point me in the right direction. My Yamaha 150 four stroke(2007) has been running perfectly until yesterday, at tickover it's started hunting between 500-800rpm, I've changed the water separator filter but didn't have a fuel filter element for the filter on the front of the engine under the cowling.

Just in case the primer bulb was the issue I've also removed this using a 3/8th connector.

When running the engine in gear I'm getting 5100rpm, I normally get about 5300-5400rpm depending on conditions.

Any ideas anyone??

matata · 30 March 2019, 19:24

I'll put money on the injectors need cleaning...not a big job but id get it done by yam....Also use a racor 2 micron filter...Nik

Pipster100 · 30 March 2019, 20:04

That was sort of my thinking too, friends 115 had similar (but much worse in terms of overall power) problems. I’m going to book it in with the local dealer.

matata · 30 March 2019, 20:32

My mate and I have a 150 yam and a 115...beautiful engines and bullit proof. The only problem these days is a tiny filter in the VST and filters in the injectors that get clogged over time.. they're like cigarette filters ....We've run 2 micron Racor filters for the last five years and its helped loads. We had to order them from the States...Google Racor S3228SUL... they're about £25 each with a plastic bowl on the bottom that lets you see any crud/water and very easy to drain it off. Yam will send back a calibrated sheet of the injector patterns and matched flow rates. Keep us posted....I like to hear the conclusion to these. nik

Pipster100 · 30 March 2019, 20:48

Cheers Nick,
I’ll keep you posted. I’m lucky that Rock Marine Services are only about an hr away and they have all he equipment to ultrasonic clean and test the flow rate.
The current filter is 10 micron so sounds like you have a better setup.
I’m back offshore soon so might have to wait till I get home before I can get it sorted.
Chris