Replacing damaged tach and resolving idling issue

 As I work to get the Sammy back online fully, one task was to re-connect the wiring for the Bosch Tachometer I'd added prior to the last camping trip.

Got everything connected, using a fuse tap this time for power, and the darn thing gave me weird readings.  The tachometer's needle would actually move backwards or counter-clockwise as I accelerated.  Sigh, another victim of the high-voltage incident.

So I got another one from the local auto parts store.  Hooked it up with no major issues and it worked fine, but it was reporting an idle RPM reading of 1500 RPMs!  Too high.  The Samurai manual says between 800-900 I think and the shop had set it to 825 RPMs.

Dinked with what I thought was the idle set screw but found out via chat conversation with the Sammy Guru in New Mexico aka Mike W. that I was actually turning the adjustment screw for the lower butterfly valves in the carburetor!  Doh!

the wrong screw

photo courtesy of Mike W.

So I put that screw back to where it was, at least I hope so.

Then, this morning, after the engine had warmed up and the thermal choke had cut off, the tachometer once again reported 1500 RPMs.  I tried adjusting the right idle screw this time, a full turn out, no effect.  A full turn in, no effect.  Huh?

Here's two views of the correct adjustment screw, courtesy of Mike W., the Sammy Guru, the circled in red item is the correct adjustment screw for the idle.

Then I thought of another thing to check that had been suggested to me by the Sammy Guru.  There's something called a idle-up actuator that raises the idle when a load is put on the engine at idle (such as lights, AC, etc), it also works to "compensate" for higher altitudes apparently.  

In the picture below, the green circle shows the idle-up actuator rod (white) and the red circle shows the point where it pushes to raise the idle RPMs.

photo courtesy Mike W.

I'd noted the idle-up actuator's rod position prior to engine start and it hadn't been in contact with the throttle assembly.  Now with the engine warmed up, it was in contact!  Per Mike W.'s instructions, sort of, I traced the vacuum line from top of idle-up actuator to the front of the engine where it connected to a two-port VSV or Vacuum Switching Valve.

I pulled the vacuum line belonging to the idle-up actuator and lo and behold the RPMs immediately dropped to 950 or so!  I looked and the idle-up actuator's rod had indeed retracted away from the throttle mechanism!  Wow.

So, I took the Sammy out for a short test drive (five miles or so) and she did just fine, the idle RPM always coming back to 950 to 1000 RPMs at idle.  She seemed responsive (well as responsive as a Samurai can be in my experience) and I returned home.

I capped off the disconnected vacuum line and port at the VSV for now.  One can achieve the same effect apparently by disconnecting the electrical connection for the VSV but this will do for now.

More driving to be done to ascertain this "fix" didn't cause other issues or I didn't cause something else by dinking with the wrong screw initially!