MRI-Denver extended run fuel tank does not work on Champion gas generators

[stephensatt]

I can confirm that the extended run tank from MRI-Denver that is sold on Ebay does not work with the Champion 3400 Remote Start Gas only model generator. The seller did refund my money back without issue, but never responded to any emails I sent about problems I was having so I tried everything in the book.

I did purchase it and you will get about 10 minutes if the tank is not elevated above the generator.

You will get about 1 hr if the tank is above the generator some, and you will get a little longer if you put the tank way up on a bar stool several feet above the generator.

Blocking off the in tank copper vent tube doesn't work right, and also sticking a brass T connector on the line going to the carb will not work either. I tried that for a more direct connect someone was doing on Youtube, and I also got about 1 hr.

What I have found is the generator uses a pure gravity feed system where no "Venturi" forces add up meaning the gas must fall in a straight line straight down because the carb creates NO suction at all and relies on gravitational pressure PLUS I think the charcoal can vent system adds some pressure bank into the fuel tank.

What this means is that the fuel spout exiting the tank goes straight out the bottom and not the top. Any tank that uses a hose that exits the top will depend on Venturi forces to create a vacuum to cause the fuel to go up the hose and then over the edge and fall a sufficient level to keep the flow going.

This is where it breaks down. The generator uses so little gas as it runs, there isn't sufficient pressure to suck the full down, and its eventually loses the Venturi suction thats created, and no matter what you do, the generator will eventually stop running within 2 hrs. It may be possible that with a much thinner fuel line, you might be able to make this work, but I haven't tried that.

Pinellas Powersports online is selling a more specialized kit for the Champion that has a pressure driven fuel pump with it and it will probably work correctly and thats what I am going to try next.

[SeaDog]

Thanks for the info ma save someone allot of trouble

[TitanMike]

First, no carburetor "sucks" gas from the gas tank . Gas flows either by gravity or is pumped into a "float bowl/chamber in the carb and is then sucked into the venturi by air passing through.

The Champion does not have a fuel pump and thus relies on gravity for fuel flow into the carb from it's onboard tank.

There are various schemes for pumping fuel into the carburetor, some using a small electric inline pump, a crankcase mounted diaphragm type pump that uses pulses from the crankcase to pump fuel, kind of like how a chainsaw carb recieves fuel even if the saw is upside down. Not the Champion.

An extended run tank for a Champion would be possible if it is a gravity system and merely refills the generator tank using a float valve much like what is used to fill a toilet tank. As the fuel in the OE tank is consumed, more runs in from the auxiliary tank with the float valve maintaining a preset level.

As for my Champion 3500 watt inverter, if I need to run it all night for A/C I'll just hook it to a 20# propane tank and let it run for the next 15 hours. I carry two just for that purpose along with 12 gallons of gasoline.