On This Page:

•  The Reason for a Fuel Shut Off Valve
•  ONAN Generator - Installing a Fuel Shut Off Valve
•  GENERAC Generator - Installing a Fuel Shut Off Valve

The Reason for a Fuel Shut Off Valve

The fuel for the generator comes out of a separate dip tube in the Rialta gas tank.  It is pumped by a separate 12 VDC low head fuel pump located near the back of the generator on the right hand lower side then through a fuel filter and into the carburetor.  When you push the start switch for the generator you activate the fuel pump and it keeps running as long as the generator does.  The standard way to stop the generator is to short out the ignition through the kill switch on the panel.  This leaves the carburetor full of fuel which is subject to evaporation and thusly the formation of varnish in the carburetor.

A better way to stop the generator would be to cut off the fuel supply and let the carburetor empty out thus preventing the root cause of varnish.  We think this solution has a lot of merit and certainly an easier solution than the recommended constant “exercising” put forth by Onan.  Varnish can’t form in an empty carburetor!!!

The easy method to cut off the fuel supply to the carburetor is to install a shut off valve.  The installation and proper use of a manual fuel shut off valve in your generator fuel line prevents the formation of “varnish” in your generator carburetor and “varnish”, which is not covered under warranty, is the single biggest cause of generator failure.

The way this works is as follows: If you know that you are not going to be using your generator for the next few days or few weeks, close the manual fuel valve while the generator is still running.  The carburetor will empty out and the motor stop.  Present day gasoline being what it is, it will help your Rialta and your generator if occasionally you put a can/bottle of injector/carburetor cleaner in the Rialta fuel tank.

You will need the following parts, all available from NAPA for less than $15 total.

 about 18” of 5/16” fuel line.

 one in-line 5/16” fuel valve w/ barbed ends.

 five hose clamps

Proceed as follows:

1. Remove the short piece of hose connecting the fuel filter to the carburetor
2. Cut the 18” fuel line into appropriate lengths and splice the in-line valve into the system between the fuel filter and the carburetor.
3. Fasten the system to keep it from flopping around such as the plastic wire ties,

For those who are a bit timid about doing it themselves, most any RV Dealer will do it for fifty bucks.

 

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ONAN Generator - Installing a Fuel Shut Off Valve

NOTE - The following mod was originally submitted to the Tech Rally group by RayWilkes August 2004 updated December 2005

This simple modification prevents the build up of varnish and gum in the generator carburetor, which may occur when the generator is not used for more than a month.  A metal valve is placed in the fuel line for the generator, in order to shut off the fuel supply, so the generator maybe run until the fuel is exhausted. PDF (29KB)

APPROX. MODIFICATION TIME:.5hours

PART LIST:

All prices are approximate, pre-tax, and pre-shipping.

NOTE: These parts work for both the Generac and Onan generators.

Remove the existing fuel line hose from the input to the carburetor [upper part of photo].
 

Route original fuel line and fuel filter as shown, behind oil filler tube, and secure with a tie strap as shown.
 

Insert the assembly of the shut off  valve and its two fittings.
 

With hose clamps in place, put the12"piece of fuel line on to the carburetor and the other end of the valve assembly.  When installing the hose clamps, be sure they are turned so that when tightened, they will not interfere with the operation of the shutoff valve.
 

Tighten the hose clamps, and you are ready to try it.
 

Be certain that there are no leaks!!  I always have a fire extinguisher handy when working on things that can burn!
 

Turn the fuel valve to on, start the generator and run it for a while to further check for fuel leaks.
 

Turn the shutoff valve to the off position [Crosswise the shut off valve] and let the engine run until it protests and finally stops.  [Around 2 minutes]
 

Run at least another cycle to be sure it all works O.K.
 

The generator should have the shut off valve closed and allowed to run until it quits when the generator will not be used for any extended period, such as two or three weeks.  The next time it is started, allow a few seconds of extra cranking, for the fuel pump to operate and fill the carburetor fuel bowl far enough for the generator engine to have fuel available and to start running.

 

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GENERAC Generator - Installing a Fuel Shut Off Valve

NOTE - The following mod was originally submitted to the Tech Rally group by Holly Towne in August 2004. Additional photos added from her similar posting at http://www.myhome.org/rialta99QD/Generac.htm.

This simple modification prevents the build up of varnish and gum in the generator carburetor, which may occur when the generator is not used for more than a month.  A metal valve is placed in the fuel line for the generator, in order to shut off the fuel supply, so the generator may be run until the fuel is exhausted. PDF (62KB)

APPROX. MODIFICATION TIME: < .5 hour

PART LIST:

All prices are pre tax.

TOOLS & PARTS:

INSTRUCTIONS:

Locate the fuel line, on the right, reroute it so it gets close to the other item that you check often, the oil dipstick.  Mark the fuel line on either side of the square section of the valve.  (We used a silver sharpie.)

 

Clamp off the fuel line at the upper right.  Cut the fuel line at the lower mark.

 

Slip the clamp on the tube.  Insert the bottom of the valve, slide the clamp up and release.

 

Cut the fuel line at the upper mark.  Slip the clamp on the tube.  Insert the top of the valve, slide the clamp down and release.  Be sure to check for leaks.

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Additional Modifications: