Onan 4.0 Generator
bal...@ezin.net
been causing us some problems lately. The crazy thing will run fine for
about 2 hours. Then it will die...slowly, as if it is running out of
gas. Of course there is plenty of gas in the tank, but it will slowing
die. After letting it sit without running for an hour or so, it will
start right back up and run for another 2 hours (The time isn't to the
minute), and then die again. I have checked everything that I can think
of to check, anyone have some suggestions?
Thanks, we appreciate any input someone may have.
ba
James Summers
This sounds like gas starvation. Check the vent in the gas cap.
--
James Summers
microSumms Computing, Round Rock, TX
Wood working, travelling, other fun stuff, "old" space guy, and retired
IBMer
Lou Schneider
: We have an Onan 4.0 Generator in our 73 Winnebago motorhome that has
: about 2 hours. Then it will die...slowly, as if it is running out of
: gas. Of course there is plenty of gas in the tank, but it will slowing
: die. After letting it sit without running for an hour or so, it will
: start right back up and run for another 2 hours (The time isn't to the
: minute), and then die again. I have checked everything that I can think
: of to check, anyone have some suggestions?
Check the fuel tank vent for blockage and the condition of the fuel line.
Sounds like the tank is developing a partial vacuum as you withdraw fuel,
cutting off fuel to the genset, possibly by collapsing the flexible hose.
After it sits for a while the vacuum bleeds off, allowing another round of
operation.
A quick way to check the tank vent is to remove the gas cap. If you hear
an inrush of air, or the generator suddenly starts running better, you
have a plugged vent.
Good luck!
Lou Schneider
lo...@crl.com
Escapee # 31721
Byron D. Krohn
>
> We have an Onan 4.0 Generator in our 73 Winnebago motorhome that has
> been causing us some problems lately. The crazy thing will run fine for
> about 2 hours. Then it will die...slowly, as if it is running out of
> gas. Of course there is plenty of gas in the tank, but it will slowing
> die. After letting it sit without running for an hour or so, it will
> start right back up and run for another 2 hours (The time isn't to the
> minute), and then die again. I have checked everything that I can think
> of to check, anyone have some suggestions?
>
>
> ba
First guess: Vapor-lock due to over-heating in the compartment. ie. temperature, IN THE COMPARTMENT, above the vapor temp-pressure of the
gasoling in the fuel lines/carborator. Causing "bubbles" in the fuel input subsystem. Check for clear ventelation of the compartment,
porper operation of the fan. (s). Maybe put a thermomerter in the compartment to check temp. while running. Should not be much above 110
deg F.
Just a guess,
Byron, in Austin, TX
Keith Rogers
>We have an Onan 4.0 Generator in our 73 Winnebago motorhome that has
>been causing us some problems lately. The crazy thing will run fine for
>about 2 hours. Then it will die...slowly, as if it is running out of
>gas. Of course there is plenty of gas in the tank, but it will slowing
>die. After letting it sit without running for an hour or so, it will
>start right back up and run for another 2 hours (The time isn't to the
>minute), and then die again. I have checked everything that I can think
>of to check, anyone have some suggestions?
>
>Thanks, we appreciate any input someone may have.
Onan generators are serviced nation-wide by Cummins, the diesel
people. Check with anyone of them.
Steven L Fletcher
> We have an Onan 4.0 Generator in our 73 Winnebago motorhome that has
> been causing us some problems lately. The crazy thing will run fine for
> about 2 hours. Then it will die...slowly, as if it is running out of
> gas. Of course there is plenty of gas in the tank, but it will slowing
> die. After letting it sit without running for an hour or so, it will
> start right back up and run for another 2 hours (The time isn't to the
> minute), and then die again. I have checked everything that I can think
> of to check, anyone have some suggestions?
>
> Thanks, we appreciate any input someone may have.
>
> ba
It may be time to change the fuel filter.
If that doesn't work, then you may have gunk in the fuel tank that plugs
the intake while the generator is running. Then, when you shut off the
generator, the gunk floats away to allow gas to flow again.
--
Steven Fletcher
Yuba City, North California
Visit My Web Site at- http://WWW.syix.com/fletcher
Visit My Home Town Web Site at- http://WWW.syix.com/yubacity
hal...@prolog.net
>We have an Onan 4.0 Generator in our 73 Winnebago motorhome that has
>been causing us some problems lately. The crazy thing will run fine for
>about 2 hours. Then it will die...slowly, as if it is running out of
>gas. Of course there is plenty of gas in the tank, but it will slowing
>die. After letting it sit without running for an hour or so, it will
>start right back up and run for another 2 hours (The time isn't to the
>minute), and then die again. I have checked everything that I can think
>of to check, anyone have some suggestions?
>
>Thanks, we appreciate any input someone may have.
>
>ba
Did you check for a dirty fuel filter?
============================================================
Hal Amos. Mechanicsburg, PA
hal...@prolog.net
============================================================
Charlotte Maxwell
or for some other reason, a vacuum could be forming in the tank and
stopping the flow of fuel. A couple of hours later (through leaks) the
vacuum would be gone, and the generator would start.
good luck
--
Clarke Maxwell
On-the-Road in Mountain Home, TX
Bryan Andersen
>In article <31719A...@ezin.net>, bal...@ezin.net wrote:
>> We have an Onan 4.0 Generator in our 73 Winnebago motorhome that has
>> been causing us some problems lately. The crazy thing will run fine for
>> about 2 hours. Then it will die...slowly, as if it is running out of
>> gas. Of course there is plenty of gas in the tank, but it will slowing
>> die. After letting it sit without running for an hour or so, it will
>> start right back up and run for another 2 hours (The time isn't to the
>> minute), and then die again. I have checked everything that I can think
>> of to check, anyone have some suggestions?
>>
>> Thanks, we appreciate any input someone may have.
>>
>> ba
>It may be time to change the fuel filter.
Fuel filter problems would show up earlier in the run time than 2
hours into it.
>If that doesn't work, then you may have gunk in the fuel tank that plugs
>the intake while the generator is running. Then, when you shut off the
>generator, the gunk floats away to allow gas to flow again.
Dirty fuel tanksand pickups also would likely show up sooner to, and
also be much more likely to createa more random shutdown than a two
hour run time.
A someone mentioned, checking for a vacuum in the fuel tank is
a possibility. It should go away when you open the tank cap. and the
engine will restart imediatly so I don't think that is the problem.
Things I would check:
Running Tempeture - Is it running to hot and after running awhile
it is getting into voporlock?. This could be cause by running to rich,
or possibly something in the fuel system becoming closed off because
it overheheats after a while running. Also you can check to see if it
is getting proper cooling, but this is likely less of a problem than
running to rich as it was suposidly working fine before this problem
came up.
--
Bryan Andersen <-O.O O.O-+ Diversity is the spice of life.
+-O.O \_/ \_/ O.O->
br...@winternet.com \_/ <-O.O-+ \_/ SF Fan.
\_/
pas...@cloud9.net
:
: We have an Onan 4.0 Generator in our 73 Winnebago motorhome that has
: been causing us some problems lately. The crazy thing will run fine for
: about 2 hours. Then it will die...slowly, as if it is running out of
: gas. Of course there is plenty of gas in the tank, but it will slowing
: die. After letting it sit without running for an hour or so, it will
: start right back up and run for another 2 hours (The time isn't to the
: minute), and then die again. I have checked everything that I can think
: of to check, anyone have some suggestions?
I bet it's a bad fuel pump. We have a 1976 Onan 4.0 generator, which
needed a fuel pump replacement when almost new. No need to get an Onan
replacement -- the generic electric fuel pumps (look like a brass
cylinder, perhaps 2 inches dia by 6-8 inches long) work just fine, and are
cheap enough to try.
Pete
jac vinson
In article <bryan.8...@winternet.com>, br...@winternet.com (Bryan Andersen) says:
>
>flet...@syix.com (Steven L Fletcher) writes:
>
>
>>> We have an Onan 4.0 Generator in our 73 Winnebago motorhome that has
>>> been causing us some problems lately. The crazy thing will run fine for
>>> about 2 hours. Then it will die...slowly, as if it is running out of
>>> gas. Of course there is plenty of gas in the tank, but it will slowing
>>> die. After letting it sit without running for an hour or so, it will
>>> start right back up and run for another 2 hours (The time isn't to the
>>> minute), and then die again. I have checked everything that I can think
>>> of to check, anyone have some suggestions?
>>>
When I had this problem it took months and lots of $$$ to finally trace it
down to a bad coil. cost to repair was about $30, cost to diagnose was
$1000+. The symptoms were: it ran fine for a few hours, then would
suddenly shut down. I could restart it but could put no load on it. after
a few minutes it would run fine but would shut down again on a shorter and
shorter run time. When it was completely cool, it would start the whole
game over again.... fwiw.. jac