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 > Running portable generator off vehicle fuel tank.

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jjrbus

FT Myers FL

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Posted: 09/19/22 04:28pm Link  |  Quote  |  Print  |  Notify Moderator

On another forum someone posted about running a Honda EU2200i off the original fuel line from the removed Onan. I have been using the mighty little Honda forever and never heard of tapping into the vehicle fuel supply. Does not seem right? Any input on this.

Lwiddis

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Posted: 09/19/22 04:36pm Link  |  Quote  |  Print  |  Notify Moderator

I wouldn’t consider this idea. Others might. I want my TV’s fuel supply not to have “stealth” drainage.


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opnspaces

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Posted: 09/19/22 07:00pm Link  |  Quote  |  Print  |  Notify Moderator

I don't see why not. The Honda has a fuel pump so I imagine it would work just fine with a modified fuel cap like those for running extended tanks.


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Bobbo

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Posted: 09/19/22 07:51pm Link  |  Quote  |  Print  |  Notify Moderator

I just use an extended run fuel system. The 6 gallon tank lasts a couple of days at moderate amp draw.

Extended Run System

[image]


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Skibane

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Posted: 09/19/22 10:36pm Link  |  Quote  |  Print  |  Notify Moderator

You'll need a low-pressure electric fuel pump (to replace the one on the Onan you yanked out of the RV), along with an adjustable fuel pressure regulator to reduce the fuel pump's 4-5 PSI output to just a small fraction of a PSI (which is what the pressure coming out of a gravity-fed fuel tank would normally be).

This prevents the generator engine from running rich or flooding out, due to excessive fuel pressure.

For safety's sake, the electric fuel pump will need to be connected so that it shuts off if the generator engine dies for any reason.

Many portable generators have a 12 volt DC "battery charger" output that can be used for this purpose - basically, the battery charger output powers the fuel pump whenever the engine is running.

You'll also need to add a "prime" bypass switch that allows the fuel pump to be manually turned on for a few seconds while starting the generator.

jjrbus

FT Myers FL

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Posted: 09/20/22 04:49am Link  |  Quote  |  Print  |  Notify Moderator

I have used the external tank for years. My concern is the vehicle fuel system is pressurized, would it push fuel through the Honda? Just does not sound right.

wa8yxm

Davison Michigan (East of Flint)

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Posted: 09/20/22 05:01am Link  |  Quote  |  Print  |  Notify Moderator

Skibane wrote:

You'll need a low-pressure electric fuel pump (to replace the one on the Onan you yanked out of the RV), along with an adjustable fuel pressure regulator to reduce the fuel pump's 4-5 PSI output to just a small fraction of a PSI (which is what the pressure coming out of a gravity-fed fuel tank would normally be).


With most makes of generator you are correct.

With a HONDA. they put on on the generator at the factory.

As someone posted up thread the HONDA is designed to suck fuel from an external "Extended run" tank. they even showed a photo of the set up.
Honda sells the tank and the "Modified" gas cap needed to use it.

The procedure is fill the "on board" tank. and the external. replace the original gas cap with the "extended run" cap and it sucks the extended tank dry. You then swap caps back (Running off the on board) While you run to ye old fuel pump to refill the extended tank.. Can run a long. long, long time that way.



TO THE ORIGINAL POSTER

Be sure to put a shut off valve line (two in fact) in the line from the RV's primary tank. One manual and one "Quick Disconnect" type to insure the line does not express fuel when the tank is filled.


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Skibane

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Posted: 09/20/22 12:16pm Link  |  Quote  |  Print  |  Notify Moderator

wa8yxm wrote:

With most makes of generator you are correct.

With a HONDA. they put on on the generator at the factory.

As someone posted up thread the HONDA is designed to suck fuel from an external "Extended run" tank.


Drawing fuel from a tank sitting right next to the generator isn't the same as drawing it through several dozen feet of fuel line to a tank mounted somewhere else on the RV.

Depending on the particular RV, there may also be some additional restriction from a fuel filter.

wa8yxm

Davison Michigan (East of Flint)

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Posted: 09/20/22 03:35pm Link  |  Quote  |  Print  |  Notify Moderator

jjrbus wrote:

I have used the external tank for years. My concern is the vehicle fuel system is pressurized, would it push fuel through the Honda? Just does not sound right.


The vehicle fuel system is not pressurized... There is a pump (External to the ONAN generators but very close to it)( specific to that line. the line pre-that pump is not pressurized might be slight vacuum in fact.
A Separate line to the main engine IS pressurized. But that is for the Motor home's motor.

valhalla360

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Posted: 09/20/22 04:18pm Link  |  Quote  |  Print  |  Notify Moderator

Modern vehicle fuel systems are sealed for emissions reasons and get fussy if that seal is lost. How exactly would you be tapping into the tank?

The outboard tank with honda transfer cap really makes far more sense.


Tammy & Mike
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