Date: Sun, 6 Jul 2008 09:04:14 -0600
Hi Micha,
Good in-the-field, logical troubleshooting on your part.
Here's your next step -- You'll need an ohm-meter that can measure
resistance in ohms.
The shifting is accomplished with electromagnetic "stationary"coils (one
each forward and reverse) as well as clutch springs (again one each forward
and reverse). When energized with +12 v dc current the coil/spring
combination causes the driven gear to engage in either forward or reverse.
Basically four elements have to be present or available for shifting to
occur:
1) Complete Positive Circuit path for Forward and Reverse (thru internal
down-leg harness LIGHT-BLUE = FORWARD, LIGHT-GREEN = REVERSE)
2) There must also be a COMMON return GROUND PATH BACK THRU the down-leg and
thru the intermediate housing. OMC offered a ground-strap kit, but since you
have current flow on the reverse circuit this path is NOT likely your
problem. But check the resistance bewteen the downleg and the engine anyway.
Should be essentially close to zero ohms.
3) Each staionary coil should draw approximately 2.25 Amps at 12 v dc.
Using Ohms law this is easy to measure with a static resistance measurement.
First locate a decent ground point on the down leg and place on probe of the
ohmeter there. The second probe should go to the LIGHT-BLUE or LIGHT GREEN
stern drive terminal with the remote control disconnected. Your ohmmeter
should read approximately 12.00 / 2.25 = 5.3 ohms, which you can round off
to 4 to 8 ohms. (An open circuit would yield very high resistance -- A
broken or high resistance connection in the wiring would cause this, as
would an open staionary coil.)
4) If all the electrical checks prove OK, then you have a defective clutch
spring. These have a tendency to fail (physically break) when shifted from
neutral into gear above the recommended idle RPM speed (typically 550 to 650
RPM).
If I had to guess -- you'll find the problem in either step 1 or 4.
I'm writing this from memory, so any one elese feel free to jump in.
Oh, here's a decent picture to better understand what's inside the gearcase:
Also see:
http://hhscott.com/evinrude/omc_stringer.htm
Lee Shuster
Salt Lake City
----- Original Message -----
From: "Micah Donahue" <mdonahue@...>
To: <omc-boats@...>
Sent: Sunday, July 06, 2008 6:27 AM
Subject: [OMC-Boats] Reverse works great, but...
> ...it's tough to pull a skier in that direction.
>
> We had our '68 Sportsman 155 in the water yesterday for a sea trial.
> Started and ran flawlessly, and shifted fine into reverse to back away
> from the dock. But it wouldn't shift into forward gear.
>
> We ruled out the console push-button switches by reversing the 2 wires
> where they connect to the wires that go into the intermediate housing
> of the outdrive. Then, as you'd expect, it shifted into reverse by
> pushing the *forward* shift button. But from that point, we got
> nowhere. We assume the problem is either:
> a) a break in the "forward" wire somewhere in the run from engine
> compartment to lower unit
> b) bad shift solenoid (assuming that's what you'd call the part that
> does the shifting)
>
> Obviously, next step is to dive in w/ the manual and start looking for
> wiring problems as the wiring goes from engine compartment to lower
> unit. Then check the operation of the solenoid. As we do that, any
> suggestions? Any "duhh" solutions we're missing? Thanks in advance.
>
> -Micah
>
>
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