Add a fuel shut-off to onboard generator

[jpcoll01]

I was reading a thread about letting a motorhome sit and it got me thinking about storing my MH this winter.  I actually use mine every couple months but it does sit up to 60-70 days at some point.  My on-board generator doesn't have a fuel shut-off but I just replaced the fuel filter and the line is very easy to get to.  I was thinking, add a shut off, run it until it goes dry, try to start it a couple times after to get the carb completely dry.  Does this make sense?  Can anyone see a reason not to do this?  I do add Stabil, but I like to store with a full tank of fuel and that gets to be a lot of Stabil.

[Darryl&Rita]

Put a switch on the fuel pump. My hands always smell like gas whenever I get near a fuel line. 

[oldjohnt]

I assume it has an electric fuel pump ?? As posted above an On/Off electric switch could be added PROVIDED THAT doing so doesn't interfere with its other control circuitry and functions ??? As far as a manual in line gas shut off (maybe say a 5/16 or 3/8 inch) those are as cheap and common as one can get and are available at auto stores and lawn mower shops.

Regarding the carb (if its a gas genset) I'm a fan of Sta Bil and regardless of how much it takes, that's cheap maintenance over the long haul in my opinion. An additional long term storage option is to use Marine Fogger spray prior to storage.  When I was in the business or farming and had to let equipment set idle for long periods I blended a bit of Two Cycle Motor Oil such as Mercury Quicksilver into the gas and let the engine run long enough so the carb got a good swallow hoping to leave a light oil film deposit inside the carb.

I figure if you use Sta Bil and fog the carb with Marine Spray Fogger that's a good long term storage procedure. I'm sure the other fine gents have other tips and procedures they prefer, but the above always worked well for me.

 

John T

[Kirk W]

5 hours ago, jpcoll01 said:

do add Stabil, but I like to store with a full tank of fuel and that gets to be a lot of Stabil.

I never store a vehicle without the fuel tank full as it can collect moisture if it isn't.

1 hour ago, oldjohnt said:

When I was in the business or farming

My goodness! Is there anything you haven't done? Electrical engineer, attorney, RV dealer/maintenance tech., and farmer too?  WOW!

[oldjohnt]

30 minutes ago, Kirk Wood said:

My goodness! Is there anything you haven't done? Electrical engineer, attorney, RV dealer/maintenance tech., and farmer too?  WOW!

Thanks Kirk, yep I've had a very FULL and rewarding life. In the seventies I quit a good paying job as an Electrical Engineer and bought a farm. Then the time came when you had to go big or get out so I chose to go back to work lol. After I took an early engineering retirement I then went to Law School and now although I'm mostly retired and travel I still practice law (Estates and Probate mostly) when I'm home a few months in the summer. In October I will be heading your way with stays in SKP in Livingston,  Austin, Corpus Christi and South Padre before heading to Florida.

Take care Kirk, best wishes

John T

[dartmouth01]

Another idea of note would be to find ethanol free gas and fill up the tank if possible.  Thankfully I've got at least 2 stations near my current fulltime spot that have ethanol free (one of them being 100 octane race gas!) at the pumps). 

 

As for those advocating putting a fuel cut off, could this potentially affect the pump in any way?  I'm assuming you'd put it on the outlet side of the pump, since putting it on the inlet side would starve the pump, which I'm going to assume is no bueno?

[oldjohnt]

2 hours ago, dartmouth01 said:

I'm assuming you'd put it on the outlet side of the pump,

In the event one chose to use a fuel shut off, that's where I'd install it. I don't like any more restrictions then absolutely necessary in the suction side of those electric fuel pumps.

John T

[Kirk W]

31 minutes ago, oldjohnt said:

In the event one chose to use a fuel shut off,

While it was in a 1987 motorhome, I put a manual valve in the fuel line of an Onan that I later took out when the fuel pump failed and the Onan tech side that valve was the reason. The valve was on the downstream side. I don't know if that was true but I assumed that it was. 

[oldjohnt]

14 minutes ago, Kirk Wood said:

I put a manual valve in the fuel line of an Onan that I later took out when the fuel pump failed and the Onan tech side that valve was the reason

I guess that could be true (Never say Never), I'm certainly not an Onan tech.  So if a person "chooses" to install one he might wanna do some research first. I had good results using Sta Bil and Marine spray fogger, although I ran across many used RV's I purchased that required a good genset carb cleaning. Perhaps the previous owner didn't perform the kind of preventive maintenance many of us here might utilize ? 

John T

[dewilso]

I’ve been considering a valve on mine also, but I’m looking for a petcock with 3 taps. I want to be able to open the line to atmosphere when running the generator dry. I don’t believe it would be very effective, when trying to empty the carb, to have the generator sucking on a closed line.

Some snowmobiles had the petcock I need as they had individual main & reserve fuel tanks. Just REAL tuff to find snowmobile parts around Livingston!

[jpcoll01]

Confused, is there a fuel pump somewhere outside the Gen?  I thought the fuel was just gravity fed and pulled by the Genset.  

[Lou Schneider]

1 hour ago, dewilso said:

I’ve been considering a valve on mine also, but I’m looking for a petcock with 3 taps. I want to be able to open the line to atmosphere when running the generator dry. I don’t believe it would be very effective, when trying to empty the carb, to have the generator sucking on a closed line.

The carburetor doesn't suck on the fuel line, it has a float chamber with a needle valve and float ... kind of like the float valve in your toilet bowl.

When you run the carburetor dry,  you're using up the fuel in the float bowl.  It doesn't matter if the fuel line is open to the atmosphere or not, once the fuel line pressure is gone, fuel stops coming through the needle valve and the engine will suck the float bowl dry. 

[oldjohnt]

2 hours ago, jpcoll01 said:

Confused, is there a fuel pump somewhere outside the Gen?  I thought the fuel was just gravity fed and pulled by the Genset

jpc, the RV gensets I've encountered utilize a 12 VDC electric fuel pump, IE there's no "pulling" fuel by the genset.. Its typically integrated and NOT a stand alone unit hanging somewhere outside the genset.  On some units I've encountered the pump is regulated by a pressure switch so once gas in the carb bowl reaches the appropriate level where the float rises and the needle valve closes and pressure rises it would shut off the pump.  I've also encountered some gensets where the pump continues to run/rattle even after the needle valve closes (Is it leaky??? Pump never achieves sufficient pressure??? Just how it works???).  Some gensets have a prime feature where pushing the button activates the pump (but not the starter) so the carb bowl can fill with gas prior to start up which saves starter cranking time. I'm unsure how the needle valve closing and pressure building so the pump shuts off is different then if a valve was manually closed, that's for the Onan or Generac or Kohler technicians or experts to answer. 

John T

[Darryl&Rita]

Generac uses a float switch, John. Some Kohler's as well.

[oldjohnt]

14 hours ago, Darryl&Rita said:

Generac uses a float switch, John. Some Kohler's as well.

THANKS for the info D & R...…..The many Gensets (different brands) I've worked on used the "old fashion" ? system but hey I'm often behind the times lol

John T

[Kirk W]

18 hours ago, jpcoll01 said:

Confused, is there a fuel pump somewhere outside the Gen?  I thought the fuel was just gravity fed and pulled by the Genset.  

I believe that you are thinking of a portable generator and in most cases you are correct for those. This thread is about the generator sets that are installed by the manufacturers into motorhomes and some other RVs. 

[jpcoll01]

2 hours ago, Kirk Wood said:

I believe that you are thinking of a portable generator and in most cases you are correct for those. This thread is about the generator sets that are installed by the manufacturers into motorhomes and some other RVs. 

I'll be the first to admit that I'm pretty clueless on this, but is the Fuel Pump inside the physical casing of the generator or along the fuel line between Gen and Fuel tank?

[oldjohnt]

42 minutes ago, jpcoll01 said:

I'll be the first to admit that I'm pretty clueless on this, but is the Fuel Pump inside the physical casing of the generator or along the fuel line between Gen and Fuel tank?

jpc, the fuel pump on the MANY ONBOARD RV Gensets (I'm NOT talkin about small portable carry outs) I've seen are somewhere "inside the physical casing" as you describe it. If you see the carb, the gas inlet (steel or rubber) is what connects to the fuel pumps outlet while the pumps suction input leads (often via a fuel filter) back to a motorhomes gas tank...…………..That's NOT to say some sort of an external in line electric pump may be there or have been added say if the onboard pump crapped out. Over the years I saw several "jury rigs" The pump will have electrical wiring plus input and output gas lines. 

 John T

 

[jpcoll01]

Thanks John T that answered my question. 

[dewilso]

Lou, how does the float bowl empty without suction ? What’s gonna replace the fuel that you’re trying to get out ? You only get to the point that the carb Ventura can’t draw (caused by suction) any more fuel. This leaves quite a bit in the bowl to evaporate. You can also, if you desire, use the vent side to draw Seafoam or Stabil directly into the bowl.

 

it would be really nice if we had a clue as to what generator we were discussing...

[jpcoll01]

3 hours ago, dewilso said:

it would be really nice if we had a clue as to what generator we were discussing...

It's a Generac Quietpact (can't remember which model exactly and don't have access to the RV just now)

[Lou Schneider]

On 8/1/2018 at 9:28 AM, dewilso said:

Lou, how does the float bowl empty without suction ? What’s gonna replace the fuel that you’re trying to get out ? You only get to the point that the carb Ventura can’t draw (caused by suction) any more fuel. This leaves quite a bit in the bowl to evaporate. You can also, if you desire, use the vent side to draw Seafoam or Stabil directly into the bowl.

My point was the carburetor by itself won't suck fuel out of the fuel line, it needs pressure to work.  Adding Seafoam via the third port in the valve will only work if you hold the container higher than the carburetor so it can pressure feed into it, or if you place the valve on the intake side of the fuel pump so it can do the sucking.

As far as emptying the float bowl, the bowl chamber is vented to the atmosphere so outside air replaces the fuel you're extracting.   It makes no difference if the fuel line feeding it is also open to the air or not.

You also have to be certain the open port on a 3 way valve doesn't connect to the fuel line going to the gas tank at any point, or you'll have a fuel leak if the handle gets moved to the wrong position.

[Ray,IN]

perhaps I'm not seeing the larger picture. What are you planning to do about the drive engine, that sits just as long as the genset, if you don't  use Stabil?

[jpcoll01]

Drive engine is fuel injected, way less issues in my experience.  

[Kirk W]

8 hours ago, jpcoll01 said:

Drive engine is fuel injected, way less issues in my experience.

One of the reasons that it is recommended that an RV generator is started and run on a monthly basis is to load the generator and get it heated up to drive off any accumulation of moisture from the windings and moving parts. It is probably the most common cause of generator failures in the RV. Your shutoff won't do much to prevent this.