Extended run Genny fuel tanks (CARB) BS

[Slacker]

Based on this thread:

Sams club generator

edited with link https://www.samsclub.com/p/westinghouse-igen2200-super-quiet-gas-generator/prod22464750?xid=plp_product_21 Flyer just came today, iirc sale starts tomorrow

carolinafirearmsforum.com

I bought one of the iGen2200 models.
After a few mods such as spark arrestor removal and china spark plug replacement, I'm happy for the money. It's got about 10 hours on it so far. This one will stay at my house for light duty power outages, coffee, lights, microwave etc.

When the iGen2500 went on sale for $400 I grabbed one. It will better power my portable AC unit and a larger air compressor at my hunting camp. Plus I can parralell the two units if needed.

What I didn't know was the IGen2500 falls under the CARB laws. That means a semi sealed fuel system (unlike it's smaller cousin).
CARB requirements are based on engine size.
The smaller unit falls under the specified size.

So, it looks like a charcoal cannister is used as the evap, much like cars of the 90's.
If you buy a new generator that falls under the CARB design and desire an extended tank setup, you will need to modify it into a sealed fuel system. Otherwise, the draw / suction to pull from the extended run tank will not be present.

Or use propane. I've not ventured down this path yet but may eventually, especially as non ethanol fuel becomes less available.

Vented vs non vented caps.
I'm looking for a vented cap that fits the 2500 model so I can seal up the tank. Much simpler.
2200 on the left, 2500 on the right.
Bottom pic is reversed. Yellow flipper is the vent.

 

[Jerzsubbie]

So if you’re not worried about adding an auxiliary fuel tank, are there any reasons to stay away from CARB models?

I was looking at a couple mid-sized generators for a friend a few days ago and noticed some were and some were not CARB but didn’t know the real differences.

 

[Slacker]

My experience with the "suitcase" size CARB model:

The tank is not well vented. Initial testing showed that it popped and acted as though it was not getting enough fuel. Not bad enough to make it stall but definitely could be heard. It was like a misfire about every 10 to 15 seconds. Most people probably wouldn't have noticed it but I did. That sent me down the rabbit path of replacing the spark plug with an American quality unit checking the fuel line for kinks etc etc. Initial testing, I only filled the tank a quarter full of fuel. Once I had gotten near the bottom of that I actually filled it all the way up. The skipping and popping immediately became worse with less air in the tank. I don't think the evaporative capture design works well for such small fuel efficient engines. They are extremely sensitive to pressure, altitude, debris in the fuel etc.

Additionally, the suitcase generators are serviced by dumping the oil out. this is accomplished by putting the generator on its side. What occurred with mine is fuel left the tank and saturated the charcoal canister. Once I put the fresh oil in it I tried to start it up, it was definitely having issues with airflow into the tank. This is understandable because the charcoal canister was saturated with fuel. I suppose if you were using a floor model that had a drain for the oil you would never invert it. Therefore the charcoal canister wouldn't get saturated with fuel and the tank may or may not continue to vent properly.

My initial experience was that the charcoal canister creates a small negative vacuum in the tank. this is because one side of the charcoal canister is connected to the engine intake which by design is pulling. This will create a small vacuum in the tank while it's running. As the engine RPM goes up so does the vacuum.

 

[DangerRuss]

Can you remove/disable the charcoal canister? Could you use the vent hose from the tank to the canister to make a true vent for the fuel tank? Like just vent it to the air, with a cap or valve on that hose that you close to seal it off when not running the gen?

 

[Slacker]

Can you remove/disable the charcoal canister? Could you use the vent hose from the tank to the canister to make a true vent for the fuel tank? Like just vent it to the air, with a cap or valve on that hose that you close to seal it off when not running the gen?

Exactly what I did. I'm going to put a 1/4" fuel filter on the vent line so dust and such isn't brought into the tank.
Eventually, I will plug that line completely and use a vented cap with ON/OFF. Just need to find one.
The extended run cap needs a sealed system to function. Having the vent line open defeats that.
In other words, the extended run fuel tanks assumed the tank was vented through the cap. That vent was removed when the extended run cap was installed. The new vent would be located in the auxiliary tank.

ETA: Apparently, the CARB compliant units are gravity feed. I'm not sure how that works since it would force fuel into the vent line.