Gendirect extended run kit for Champion generators.

[agesilaus]

OK I bought this kit for my Champion 3500/4000 digital inverter genset, tho it should have worked on the non-inverter model too since they have the same fuel cap. This is what I'm talking about. I emailed the seller before hand to check if it would work with my generator and was told that it would.

Well to cut straight to the punch line, after I cleaned up my old outboard gas tank and filled it I set up the hoses as instructed and went over to the genset to try it out. The provided cap is female thread the champion cap is male. All stop. I'm waiting for a Return Authorization.

But before you go let me explain how this kit works, which may or may not give ideas to you DIY people.

1) It has a massive machined aluminum cap, grossly over-built in my opinion.
2) The cap has a threaded hole for a 1/4 in brass tubing connector. One end of the 90 is 1/4 in npt male thread the other female. The male end is threaded into the cap.
3) They provide a 1/4 male quick connect that threads into the the female 90.
4) They provide a 3 foot length of hose, just like what's on the outboard gas tank. One end has a female quick connect and the other a male 1/4 fitting that threads into the 90 on top of the outboard tank.
5) That's just about it for the kit at $140 delivered.
6) They do give you a tiny black plastic cap that you are supposed to plug the vent on the generator tank with. I instantly lost it but found that a couple of inches of 1/4 PVC of tubing with one end heat sealed would work fine.

To operate this system you:
1) Fill both tanks
2) Plug the vent on the genset tank
3) Make sure the vent on the outboard tank is open (mine has a check valve)
And that is it, the closed gas tank pulls gas in and keeps the genset tank full.

My 3500/4000 has run 17 hours on a full, roughly 2.5 gal, tank. That's 6.8 hours per gal or round it down to 6.5. Add 6 gals in the outboard tank and that should give you 56 hours of run time. Tho I would not depend on that without testing. That is in ECO mode.

Since I has a full tank in my outboard tank, there are plenty of fittings down at the hardware store. And I have a tap and die set. I may be be tempted to save myself $140. They don't seem to have an appropriate cap anyway. It would be better to get a bulkhead fitting online for that plastic cap tho since it won't hold a thread as well as their aluminum cap.

[Boon_Docker]

GordonThree wrote:
I don't see how any strong vacuum is going to develop inside a gravity drain fuel tank. There's no pump, fuel drains into the bowl and then gets atomized using a venturi right?

Maybe the Champ has a fuel pump and that allows the system to work, and I'm comparing apples and oranges.

There is a vacuum that is produced in the Champion gas tank. I know this for a fact, I forgot to open the gas cap vent last time I use my genny.

[fj12ryder]

GordonThree wrote:
I don't see how any strong vacuum is going to develop inside a gravity drain fuel tank. There's no pump, fuel drains into the bowl and then gets atomized using a venturi right?

Maybe the Champ has a fuel pump and that allows the system to work, and I'm comparing apples and oranges.

No you're totally right, it is just a syphon. Over a $100 syphon.

It will work with the tank below the generator ONLY if the generator has a fuel pump.

[GordonThree]

I don't see how any strong vacuum is going to develop inside a gravity drain fuel tank. There's no pump, fuel drains into the bowl and then gets atomized using a venturi right?

Maybe the Champ has a fuel pump and that allows the system to work, and I'm comparing apples and oranges.

[fj12ryder]

GordonThree wrote:
Never worked for me with the tank level or below the generator.

On Edit: After further digging and checking, it would appear that the website is a bit deceiving in that the fine print states that you have to have the supply tank above the generator for the gravity feed system to work.

So I was totally off on how the system works. Yeah, basically it's just a syphon. Definitely not worth the amount of money they want for it.

[MrWizard]

SuperGen products
Did have an auxiliary extend run system, using a pump
Comes as a kit, with a manifold block, that goes between the carb and the intake
Nipple on the block supplies the vacuum for the pump

Also has a Tee that is spliced into the fuel line and another nipple to attach the extended tank

Came with everything except the auxiliary tank

Don't know if it's still available

Maybe someone has a link or phone number
I lost both

[GordonThree]

Never worked for me with the tank level or below the generator.

[fj12ryder]

GordonThree wrote:
I have the same for Yamaha, didn't pay nearly as much.

The caps have been rolling around in a tool box for years now as I found them very difficult to use.

Mainly the height of the external tank is the issue. Too low and it won't siphon enough fuel. Too high and the siphon will push fuel past the gasket in the cap and cause a leak.

I also found the gasket material to be inferior, apparently not chemical resistant as gasoline caused one to partily melt and glue the cap on to my generator.

If I were inspired, I'd add an impulse pump like the Honda uses. No more need for a siphon, or use for the on board fuel tank.

Just reading this it doesn't appear that the system actually siphons fuel from the supply tank, since they do specify the supply tank can be above or below the generator. It would seem, since you plug the vent hole, that it relies on the vacuum created as the tank level drops to pull fuel from the external supply tank.

Or am I wrong in my thinking?

[SidecarFlip]

SidecarFlip wrote:

GordonThree wrote:

agesilaus wrote:
So the vacuum on the generator fuel tank would power this pump?

Vacuum from the engine. You drill a small hole into the air filter box and cram a rubber hose in it. That gives you a little puff of vacuum every revolution. This spins the impeller in the pump and moves a little fuel.

For generators with a separate fuel shut-off (like Yamaha), you can leave the fuel tank empty and shut off, and attach the external tank after the shut-off with one of those marine style quick connects.

I think Champion have a shut-off too?

There's video on YouTube that explains it better than I can.

Not an impeller really, it's a diaphram. One side is the crankcase pulse pressure the other is fuel and the movement of the fuel is controlled with a reed valve. Everytime the engine cycles, the pressure differential pulses the diaphram and fuel moves on the wet side of the pump. Stone simple really.

Only two drawbacks but neither apply to a small engine. One, the volume is low and 2 the pressure is also low which is why they won't work with fuel injected engines (like in your car or truck) but work fine on a small engine with a carb.

I'm sure some engineer somewhere made a pile of the idea.

In reality, the best 'signal' pulse will come from the crankcase, not the air filter. The pulse from the vacuum in the air filter box is very small, whereas the pulse from the crankcase is large. Nice thing is, all modern small engines have a crankcase ventilation hose so it's a matter of using that.

[SidecarFlip]

GordonThree wrote:

agesilaus wrote:
So the vacuum on the generator fuel tank would power this pump?

Vacuum from the engine. You drill a small hole into the air filter box and cram a rubber hose in it. That gives you a little puff of vacuum every revolution. This spins the impeller in the pump and moves a little fuel.

For generators with a separate fuel shut-off (like Yamaha), you can leave the fuel tank empty and shut off, and attach the external tank after the shut-off with one of those marine style quick connects.

I think Champion have a shut-off too?

There's video on YouTube that explains it better than I can.

Not an impeller really, it's a diaphram. One side is the crankcase pulse pressure the other is fuel and the movement of the fuel is controlled with a reed valve. Everytime the engine cycles, the pressure differential pulses the diaphram and fuel moves on the wet side of the pump. Stone simple really.

Only two drawbacks but neither apply to a small engine. One, the volume is low and 2 the pressure is also low which is why they won't work with fuel injected engines (like in your car or truck) but work fine on a small engine with a carb.

I'm sure some engineer somewhere made a pile of the idea.

[SidecarFlip]

agesilaus wrote:
I did a search for crankcase differential pump and didn't find anything pertinent. What powers this?

Crankcase differential pressure (also known as blowby in some circles). It's the volumetric pressure differential that occurs when the piston is moving in the cylinder bore. All engines have it, 2 and 4 stroke.

Most differential pumps are about the size of a half dollar and an inch thick.

[GordonThree]

agesilaus wrote:
So the vacuum on the generator fuel tank would power this pump?

Vacuum from the engine. You drill a small hole into the air filter box and cram a rubber hose in it. That gives you a little puff of vacuum every revolution. This spins the impeller in the pump and moves a little fuel.

For generators with a separate fuel shut-off (like Yamaha), you can leave the fuel tank empty and shut off, and attach the external tank after the shut-off with one of those marine style quick connects.

I think Champion have a shut-off too?

There's video on YouTube that explains it better than I can.

[agesilaus]

So the vacuum on the generator fuel tank would power this pump?

[GordonThree]

agesilaus wrote:
I did a search for crankcase differential pump and didn't find anything pertinent. What powers this?

They're powered by air pressure, the vacuum pressure from the crankcase. Pulse, impulse, vacuum fuel pump.

[shastagary]

these are the kind of fuel pumps there talking about powered from the crankcase vent hose. Fuel Pump