Jerry,
   The problem is with the controls or the generator. In general, when an
Onan rv genset is starting, it ignores the local or remote stop signal as
well as the low oil pressure/low oil signal. To switch to run mode (which
will allow it to continue running with the start switch released), it
must -not- have a stop signal from the local or remote switch, it must -not-
have a low oil/low oil pressure signal, and it -must- be generating. (With
the exception of later Marquis with electronic governor - they use a signal
from the governor module instead of a voltage from the generator).
   The majority of times when I see this, it's not switching to run mode
because it's not generating. But until I know -which- 4kw genset he has,
it's kinda hard to tell him what to check and where to check it.....
for -any- of the possibilities.

Alan

ARGH!!!   [ROFL]

Dagnabbit, Hunter!  Would you PLEASE give a "spew" warning for us morning
readers (coffee drinkers)?  Sheesh!

Hehehehehe!
                   :)
JR

Ed,
   The voltage regulator module is potted, so not repairable. As to your
other suggestion, the voltage regulator module maintains the genset output
at a nominal 120v ac. It does this by turning ac voltage from a separate
winding into a variable dc voltage that is fed to the field winding of the
genset - it adjusts this dc voltage as needed to maintain the 120v ac
output. For example, most Onan 4kw gensets need about 20v dc to the field
windings to produce 120v ac output with no load. At 4kw load, it'll take
about 70v dc to the field windings to maintain 120v ac output. The module
has to be able to adjust the voltage it feeds to the field pretty quickly,
too - you don't want the ac voltage going to 80v when the air conditioner
tries to start, or to 160v when the air conditioner compressor stops.

Alan

John,
   The first thing to do is -verify- that it isn't putting out AC. The
output wiring leaves the genset from the left side of the genset pan, about
2" back from the front. Should be flexible conduit from there to a junction
box somewhere in the vicinity. Pull the cover off the junction box, should
be flexible (stranded) wires from the genset wire-nutted to stiff (solid)
romex wiring going on into the coach - black, white, and green wires.
Disconnect the black and white wires, set your voltmeter to read ac volts,
and hook one lead from your meter to the black stranded lead and the other
to the white stranded lead. Make sure the circuit breaker on the genset
control panel is 'on', then crank and start the genset. If you read low or
no voltage, that's the reason the genset won't stay running.

   Assuming you had no AC output, tape up the ends of the stranded wires so
they don't short, but leave them disconnected for right now. There's a
vertical partition just to the left of the control panel, running from top
to bottom, front to back of the genset. The area to the left of the
partition is where air is pulled into the genset. There is a metal shelf
just below the lip of the opening that runs back about 7" - it has the
starter solenoid and the voltage regulator module mounted on top of it, and
the control circuit board mounted under it. The voltage regulator module is
a metal box about 4" square and 1" high with a black cylinder mounted
horizontally in the middle of the top, and 10 wires coming out of the top.
These wires run to a 12 pin plug (P4) that plugs into a 12 pin jack (J4)
located in the partition, below the air cleaner. (There's also a 15 pin
plug/jack -P1/J1- either just above or just below the 12 pin that carries
control circuitry - can't remember which is on top right now).

   Figure out which pin is pin 7 (the wires will have identification
printed on them), set your meter to read dc volts, and slide the tip of your
positive (red) test lead into the back of the plug alongside the wire so
that it touches the pin. Ground the negative (black) test lead, then crank
and start the genset. You should see approximately 11v dc at this point
while cranking (this is the field flash). Stop the genset, squeeze the latch
ears on the 12 pin plug and disconnect it. Set your meter to read resistance
(ohms), and measure the resistance from pin 9 to pin 10 of the jack - this
is the circuit that leads to the brushes, slip rings, and the field winding.
Should measure approximately 25 ohms.

If you had 11v dc at pin 7 while cranking, and measured 25-30 ohms from pin
9 to pin 10,
get some wire and 2 9v transistor batteries. With the voltage regulator
unplugged: set your meter to ac volts, and hook it back up to the ac output
wiring. Hook the two batteries up in series to provide 18v, with a wire from
the negative terminal to pin 9 of the jack, and a wire from the positive
terminal ready to touch to pin 10. Start the genset, touch the positive to
pin 10, and look at the meter - should show 45-55v or so. Stop the genset,
hook your meter up to pins 11 and 12 of the jack. Start the genset, touch
the positive to pin 10, should show voltage approx 10-15% higher than the
output voltage was.

If all checks out, then you need a new voltage regulator.
If you haven't got field flash on pin 7, the control board or the wiring
from it to J4 is bad.
If your resistance from pin 9 to pin 10 is too high, you probably have
tarnished slip rings - and this -would- require removal of the genset.
Replacing voltage regulator or control board shouldn't.

   I'm somewhat curious as to that 750 figure. I've never worked on a
Microlite/Microquiet in a class A or C that took more than 2 hours to
remove - most much less. Is the labor rate in Knoxville -that- high?
   The dealer locator shows 6 authorized dealers within 50 miles of
Knoxville (including the distributor Cummins Cumberland).

Let me know what you find out, and we'll go from there.

Alan