Troubleshooting guide

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PREVENT FUEL VARNISHING
If You Don’t Run A Tank Of Gas A Month, You Could Be
Risking The Performance Of Your RV Generator.
If you store your RV over the winter, or don’t operate it often enough to refuel the gas
tank every month, you could develop a fuel varnishing problem in your engine —
particularly in your generator.
Fuel varnishing is a gummy residue that clogs the generator carburetor and fuel
pump. It’s caused by the deterioration of fuel that sits in the engine too long, and it
happens in a surprisingly short period of time. Depending on fuel quality and storage
conditions, gasoline can deteriorate in as little as 30 days. As long as you refuel
frequently with fresh gasoline, and exercise the unit regularly, fuel varnishing is less
likely to occur. But if you leave the same gasoline in the tank for several months,
you’re very likely to have problems.
Fuel varnishing affects many engines, but it’s more noticeable in generators because
the engines are smaller. Even the slightest decrease in efficiency has a big impact
on performance. A generator with varnish buildup may start, but runs like it needs
a tune-up. It surges, accelerating and decelerating, but never settling on a stable
operating speed.
In many of the gasoline powered units, engine speed directly affects generator
voltage output and frequency. As speed increases/decreases, so does the voltage
and frequency.
The only ways to prevent fuel varnishing are to treat the contents of the tank supplying
fuel to the generator with a fuel preservative and to exercise the set. Onan has
developed a fuel preservative and stabilizer, OnaFresh
™
, specifically formulated for
Onan and Camp Power
™
generators. We recommend adding this preservative to the
fuel, especially on infrequently used RVs.
Emptying the tank won’t prevent fuel varnishing because a small amount of fuel
always remains in the generator carburetor. If you plan to leave the tank empty, we
recommend that you add a special mixture of fuel and a preservative before you run
the tank dry so the residual fuel contains the preservative.
Once varnishing has occurred, adding a preservative won’t correct the problem.
You need to add a fuel cleaner, or manually scrape the varnish from the fuel system
parts. Onan offers Premium Fuel System Cleaner for use with Onan and Camp
Power generators.
By understanding how to properly care for your RV generator and protect against
fuel varnishing, you’ll enjoy better performance and longer, service-free operation.
It may seem strange that “not” using a product causes it to break down faster. With
generators, though, that’s exactly the case.
Premium Fuel System Cleaner and OnaFresh, along with other Green Label Parts
™
maintenance products can be found at your local Onan Authorized RV Service and
Parts Dealer. To locate your nearest dealer, visit Funroads.com.
IMPORTANT: Problems caused by fuel varnishing will not be covered under warranty.
A WORD ABOUT OIL
Use a premium quality engine oil (such as OnaMax
™
SAE-30 and SAE 15W- 40) in
the correct oil viscosity for your generator’s typical operating temperature range to
provide optimum engine service. Avoid mixing different grades or brands.
It’s good practice to check the oil level daily, or every 8 hours of operating time.
Keep the oil level as near as possible to full, but do not overfill. Overfilling may cause
foaming and engine shutdown. Replace the cap tightly to avoid leakage. And if your
generator has an oil filter, change it when you change the oil.
Do NOT check the oil level while the generator is running, because hot oil can be
thrown out of the dipstick hole, causing severe burns.
Gasoline Engine Oil Quality — Use oils meeting API performance categories SH/CE,
SH/CD, SH, SJ, SJ/CE or SJ/CD.
Diesel Engine Oil Quality — Use oils meeting API performance categories CG-4,
CF-4, CE/SG or CD/SG.
Oil Viscosities — Use the following information to select correct viscosity grades for
expected ambient temperature range.
NOTE: Multi-grade oils (such as SAE 15W- 40) are recommended for year-round use
in Onan
®
liquid-cooled engines, or as a good all-season oil for air-cooled engines.
NOTE: SAE-30 is the preferred summer grade for optimum oil consumption control in
Onan air-cooled engines.
-20°F 0 20 40 60 80 100°F
32° 100°
10° 100°
0° 100°
-20° 50°
Expected Temperature Range
SAE-30
15W-40
10W-30
10W-40
5W-30
Viscosity Grades