Yamaha 90 Emergency Fuel Enrichment System

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
frontier
Posts: 130
Joined: Tue Feb 09, 2016 8:26 pm

Yamaha 90 Emergency Fuel Enrichment System

Postby frontier » Sat Aug 17, 2019 8:59 pm

On a 1994 Yamaha 90 model TLRS two-stroke-power-cycle engine, the Emergency Fuel Enrichment System is controlled by a red lever with three positions: Normal, Open, Closed.

Would running in any position cause low idle and rough running at low-to-mid RPM when warm?

jimh
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Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
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Re: Yamaha 90 Emergency Fuel Enrichment System

Postby jimh » Sun Aug 18, 2019 8:44 am

The red lever sounds similar to a valve on my Evinrude used to create a richer fuel-air mixture for starting. If left open the engine would run very poorly due to the over-rich fuel-air mixture.

frontier
Posts: 130
Joined: Tue Feb 09, 2016 8:26 pm

Re: Yamaha 90 Emergency Fuel Enrichment System

Postby frontier » Mon Aug 19, 2019 7:50 am

This is part of the Yamaha "Prime Start" system. Years ago a trusted Yamaha outboard mechanic told me to save battery from constant cranking when cold, turn red lever down. It near always works and starts right away. I just wonder if when cold started on the trailer with muffs, maybe I didn't return red lever to "normal" position. When we got to the lake, after intial run, it wouldn't idle above 400-500 rpm and was sluggish at 1800-2000 RPM. Ran fine at high speeds. I'll test it again soon.