Tohatsu/Nissan/Mercury - Prime Starter - Choke System 9.9 15 18 HP

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Dec 2, 2022
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Chaptico, MD
Tohatsu/Nissan/Mercury - Prime Starter - Choke System

I am having trouble diagnosing the prime starter on a 2003 Tohatsu 9.9

The motor is set up with remote controls. In lieu of a conventional choke, the motor is engineered with a "Prime Starter" which is an electro-magnetic plunger. It serves as a fuel enrichment system. It's a white plastic electric component that sits atop carburetor.

The issue: The system is not working. I replaced prime starter with new. Still not working. I can measure 7 volts coming to the prime starter while cranking. Motor starts and runs if you place your hand over the air intake, but just won't fire as designed.

Question: How many volts are needed to energize the electomagnetic plunger?

Anyone have any experience with this?


  • Tohatsu Prime starter.jpg
    Tohatsu Prime starter.jpg
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I would suspect it is a 12vdc solenoid.

If you google; "tohatsu abs solenoid" there are a few forums that say to test using 12vdc.

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