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posted to rec.boats
Jim
 
Posts: n/a
Default Mercruiser Still Won't Start

Agreed that there appear to be at least 2 problems. The first issue I would
tackle is: The same wire that pulls in the starter slave solenoid enables
12V to the coil thru contacts in the slave solenoid. I am very suspicious
that you can crank the engine but don't have 12V on the coil during
cranking. The only way I can account for that is if someone replaced the
solenoid with the wrong type or if the solenoid itself is bad.
Jim

"r_d" wrote in message
. com...

I realize that my naiveté is going to show here, but the boat is on the
trailer, and is NOT connected to the truck. I should still have a
sufficient ground though... no?




The battery you are using to crank and start the boat is in the boat
right? If so then it does not matter where the boat is as it is a complete
circuit. If you can crank it then you do have power to the system.



The voltmeter is just fine. I actually use a $4 digital meter from Harbor
Freight when I work on something. Actually, have one in each car and boat
in case of break down.



You have two primary problems.



1. No power to the coil



2. No start once you plugged the coil into the battery.



First-- With the distributor cap off crank the engine a revolution or
two. Does the rotor turn? Is there a rotor installed under the cap (yes I
have done this.)?



1. You are going to have to trace the wires from the positive side of the
coil back to where they go. I suspect one leg will go to the alternator
and one to the starter solenoid. But you need to find where each of these
leads go. Once you figure out where they go with key on test each
beginning point to see if you have 12v being supplied to the wire lead.
Find a good spot on the block and use this for all of your power tests.
Be sure to also test it to the positive side of the battery to make sure
it is a good ground. The idea of tracing the wires from the coil to their
point of origin is to make sure there are no fuses or circuit breakers
that are in the system that have blown or corroded connections that are
blocking power. If you do find that you do not have 12 volt in one of
those supply locations then that will have to be explored. Be advised
that you may not have 12v coming from the alternator as this may be
powered only when the alt is actually turning but you should be seeing 12v
on the start circuit. When you have it running you will have to replace
all of the electrical tape that you will remove.



2. Remove the points negative (ground) wire from the coil. With the
points sitting on a flat lobe of the cam (points closed) put your meter
into ohms and test the resistance from the points wire (removed from the
coil) to the plate the points are sitting on (the points ground the coil
to the base plate in the distributor. You are tying to see if the points
are really supplying a ground, what resistance do you get? With this
setup in place have someone crank the engine you should now see the
reading on the meter flip as the circuit closes and opens (both of these
can be done with a test light if you have one). Next test the resistance
from the plate that holds the points to a good place on the engine block,
should see a reading of zero. Next test from the engine block to the
negative side of the battery, should see a reading of zero. If you see a
see a reading of 1 on the meter, this means the circuit is open.



Check the resistance of your coil ignition wire (wire from coil to cap
center) what do you get (your are trying to see if the wire is bad)?



Unfortunately, at this point you are on your own. Just make sure you are
seeing a real ground through the points and try to determine where in the
system the power to the coil has stopped. I really do not know what to
tell you. Hooking the coil directly to the battery should have worked.
Because it did not tells you, you have a problem with the points. They
are not pulsing the coil. And no power to the coil key on tells you there
is a power problem.



I would not get discouraged. Just systematically work you way though the
system. With the closed circuit you will see a reading of zero or close
to zero in ohms. If you see a reading of 1 then the circuit is open.



good luck,

mark