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.

On Jun 13, 3:14*pm, "Chuck" wrote:
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.

Chuck, I don't think there is a problem there. Those solenoids are
probably next to closed when the engine is cold, and as the engine
warms, there's a sensor that will allow electrical current to go
through the solenoids to open them. Almost all your carburated
automotive engines worked on this principle. where you had current
running though a solenoid of some sort to open the chokes as the
engine warmed. The reason they are hot is probably because they are
made that way. they are a "constant current" switch which takes the
voltage through a "secondary" or "hold in" coil in the solenoid
itself, and holds the chokes open. I would say that when you shut the
engine off, they release and the chokes close. Then even when the
engine is warm, if you turn the ignition back on, the solenoids will
activate to hold the chokes open.

But then again, I don't really know. I'm a starter mechanic.

Hey guys... I need more input on this one. I don't think these things
should still be energized after twenty minutes of running. When I use a
voltmeter and pulse the key nothing happens because they are already
energized. I say that after warm-up they should dropout. What do you all
say?

On Sun, 14 Jun 2009 14:46:26 GMT, "Chuck" wrote:


Hey guys... I need more input on this one. I don't think these things
should still be energized after twenty minutes of running. When I use a
voltmeter and pulse the key nothing happens because they are already
energized. I say that after warm-up they should dropout. What do you all
say?

I looked around a bit when you first posted. Enough to see that the
enrichers on Mercs are for cold engine.
My assumptions, and only assumptions is:
1. you apply juice.
2. a temp sensor in the enricher circuit says do or don't energize
enricher.
3. if it gets energized, the temp sensor also says when to turn it
off.

Should find the answer in a shop manual, or track the energizer
circuit to the temp sensor, and troubleshoot that.
Maybe a relay is stuck - if there's a relay in there.
Sometimes tapping on a sensor will tell the tale.
I told my kid to check the A/C high pressure switch wiring on his
Bonneville as a possibility for causing his cooling fans to stay on
all the time. Maybe one was off a harness and got burned or cut
by a belt.
Wires were good so he tapped the switch with a hammer handle.
Fans went off. Bad switch.
Maybe a real non-political OB mechanic will hold his nose and come in
here.

--Vic

"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.