Since I am not familiar with the setup that your generator has, I will
take a chance and maybe tell you something that may work.

Most generators won't get gas from the tank if the tank is below half
full (or half empty). :-)

If your tank is full, then it is another problem. Try shooting ether
into the carb and then try to start it. If it starts for just a second,
it is a fuel problem.

Hank <~~~~Thinks everything is half empty

The more information you give, the easier it is for people to give useful
answers. It would REALLY help to know the full model and spec of the Onan -
to the best of my knowledge, they've NEVER made a 2.2kw rv unit - so what do
you really have?

   Generally, the fuel pump should be pumping as soon as you hit the
starter -  but the last thing I'd suspect is a relay, and it's usually
pretty easy to find out where the problem lies. Disconnect the power lead
going to the pump and use a jumper to hook 12v to it. If you don't hear the
pump running, it's a pump problem. If you hear the pump running and gas
comes out, then it may be a relay/control board problem. If you hear the
pump running but no gas comes out, it's either a pump problem or a gas
supply problem (your tank IS at least 1/3 full, right?). Hook a hose to the
pump inlet and put the other end in a gas can, then use the jumper to try
the pump again - if it still doesn't pump gas, then it's a pump problem. If
it now pumps gas, then the problem is the fuel line back to the tank, or the
gas level in the tank.
Note: if it's the pump, replace with the correct Onan pump - standard car
pumps are 7+ psi, and will cause the carb (designed for 4.5psi max) to
flood.

   Once you solve the gas problem and get it running - stopping as soon as
you release the start button is a sign that the genset is not switching from
'start' mode to 'run' mode. To do this, it MUST be generating, MUST have oil
pressure, and MUST NOT be receiving a stop signal from the local or remote
start/stop switch. The most common cause is the genset not generating,
usually due to tarnish buildup on the slip rings due to lack of use. (Note -
if this is the case, it may have caused the voltage regulator to fail..).
First (because it's easiest), unplug the connector for the remote switch and
try again - if it now stays running, the problem is the remote switch or the
wiring to it. Next, check the genset output - if it's not generating, that
is the reason it won't switch to run mode.

   That's about as much as I can give you without knowing -exactly- which
genset it is. Let me know, and I'll be happy to give more detailed
directions.

Alan

My experience was that the voltage regulator in the generator needed to be
replaced. As far as the gas goes, the generator sucks that gas out of the
tank from a dedicated pickup tube that is not part of the fuel delivery
system to the vehicle's engine.