"Chuck" wrote in message
news:gMTYl.143797$DP1.124552@attbi_s22...
My neighbor has a 2001, 75hp, carbureted, four stroke Mercury outboard
(75ELPT, SN OT395139).

It idles a bit rough but runs great at full throttle and everywhere in
between.

When looking at it, I noticed that the two electric fuel enrichner
solenoids (chokes) were very hot when I touched them. I checked them with
a voltmeter and both were still energized at 13.5 volts even after the
motor had been running for 20 minutes. What is keeping them energized?

Are these enrichners activated by pressing in the ignition key like my old
Merc motor was, or are they controlled by temperature or what? Thanks.


OK. These are called "electro-thermal enrichment valves" and are designed
to run hot. Yamaha uses them too. In fact some Yamaha's were rebadged as
Mercs, (not everyone knows that but I wanted to slip it in).

Your engine has two electro-thermal valves as part of a "PrimeStart" system
(the white assemblies on the top of carburetors 1 and carburetor 3). These
valves have a needle valve assembly that controls fuel flow into the venturi
section of the carbs based on temperature. Electrical current flowing
through the valves heats up wax inside, that in turn moves the adjustment
needles which eventually "leans" out the mixture as the engine warms up.

If they are hot they are probably working. They are easy to remove and you
should be able to measure 15 - 25 Ohms across the blue (hot) and black
(ground) wires when disconnected. Once removed, you can also put 12 volts
(DC) across blue and black wires and let it sit about 5 minutes to heat up.
Just compare the length of the metering needle before and after it heats up.

Hope this helps.