Add a fuel shutoff valve Onan 5500 generator

I rarely use my generator more that a couple times a year and I don’t believe in starting it if it sits for long periods of time.

One of the problems with carburated engines that sit for long periods of time, the fuel inside the carb bowl evaporates and leaves behind a residue that can foul the float, valve, and jets.  To reduce / eliminate  this problem,  simply drain the fuel from the carb bowl before placing the generator in storage mode.  I installed a fuel shutoff valve in the fuel line that feeds the carb.  When I’m finished running the generator and don’t think I’ll be using it again in the foreseeable future, rather than shutting the generator off, I turn off the two circuit breakers on the side of the generator, then close the fuel valve and let it run out of gas.  This burns most of the fuel out of the carb, and eliminates the residue from sitting for months on end.

Onan 5500 fuel shutoff valve

IMPORTANT – I used a good quality metal valve from Amazon. The cheap plastic valves won’t seal and the generator fuel pump can push fuel through it and leak.  The cheap plastic valves are OK for gravity feed systems like my lawn mower and snow blower.  I do the same thing on them, before placing in storage,  run the motor and shut the fuel valve off so it runs out of gas.

12 Replies to “Add a fuel shutoff valve Onan 5500 generator”

  1. Great idea! I did the same exact thing. Works great..because Onan doesn’t make the Carbs serviceable and a new one from Cummins is about $500! (Although I buy OEM on Ebay for $200-$250)

    Follow this tip people!

  2. So when you cut off the ball valve and run all the fuel out of your carb. It’s ok to let the generator sit for 6 months or so without operating it every month?

    • IMHO, Yes.. Mine gets stored this way twice a year. about 6 months in Ohio, then when we go to AZ for the winter, about 5 months in AZ. Before storing, I run the genny for about 20 minutes under load. I then turn the gas valve OFF and allow the genny to run out of gas. It then sits for 5 or 6 month unless I need it for an emergency.

    • The Amazon link in the article shows “UNAVAILABLE”. However, it does show alternate items available. Looks like about $10-$12.

  3. Can you leave the links to order the parts please.

    Also, I would like a way to turn the generator on and off from my bedside table (mobility issues) and could use the walk through.

    I’m on this site specifically because I need a schematic of the top of the generator underneath the metal housing since my spring and rod have come loose from the other end. I removed the front bolts but cannot bend the metal frame up enough to look under to see where it goes. Anyone?

  4. 1999 Fleetwood Bounder 36S, Can you post information on how to add a start on/off switch because I would like a way to turn the generator on and off from my bedroom bedside table (mobility issues) and could use the walk through.

    I’m on this site specifically because I need a schematic of the top of the generator underneath the metal housing since my spring and rod have come loose from the other end. I removed the front bolts but cannot bend the metal frame up enough to look under to see where it goes. Anyone?

    Can you leave the links to order the parts for the fuel shut off and are those brushes? What is that exactly? Ty

    • There are links to the parts, operation, and service manuals in my DOWNLOAD page. Goto the DOWNLOAD page, then there is a link to list all the files that are available for downloading. Click on that link, then scroll down the list and I believe the tite for the manuals will be something like

      5500 ONAN etc.

      These manuals should provide you with part numbers, schematics, etc…

      As for the fuel cutoff valve, the Amazon link in the article should get you the valve. If Amazon shows its currently unavailable, they should offer alternative source parts.

  5. 1999 Georgie Boy Landau. Onan Emerald Plus. Here is a very simple solution to the expensive problems of those Onan carburetors plugging up with gasoline additives from drying out repeatedly.
    The 12 volt power line to the electric fuel pump goes right across at the bottom at the front there. I cut in and installed a male and female Spade connector. Then when I want to shut the generator off I just unplug that line so the fuel pump stops operating and then the float Bowl slowly Runs Out, and so it all shuts off dry, (except for the fuel pump*) . Then when I want to start it again , I first prime the carburetor by pressing the the spade connector, of the line going to the fuel pump, against the main positive 6 gge wire coming to the generator, which is right there. Then I connect the spade connectors together and start the generator.

    *( the pump can plug up from residues from the gasoline evaporating as well. So once every couple of years disconnect the input line and pump a few ounces of 50 percent Gumout to 50 percent gasoline into it. And let it sit)

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