Generator question - let carb run dry or keep it wet?

[alank2]

I was helping my father in law get his genset running yesterday and ran into the same issue we ran into about 6 months ago. It wouldn't start, was difficult to pull the cord. It would finally start up and then stop shortly thereafter and gas would burst out of the air filter box. Checking the oil area reveals that it is full of fuel! Dump the fuel and put oil back in and it will start back up and run.

Doing some reading and talking to my dad, the thinking was that something in the carb is stuck allowing fuel to slowly work its way into the engine because we are leaving the fuel switch on.

I've done this for probably 8 years with my Yamaha 3000 and had no ill effect, but am a bit concerned that perhaps that isn't the best practice. I double treat my fuel with stabil the first day I get it and it is pure gas (no ethanol).

So my question is - should the carb be left wet with treated fuel, or should I shut off the fuel switch and let it run dry. I've always thought letting it run dry might leave a little residual fuel in there that could dry up, gum up, varnish, etc.

[westend]

Besides my own household equipment, I maintained a fleet of small engines for 6 years (110 engines, IIRC). All were brought out of service in October and brought back into service in April of the following year. There were various sizes and makes.

All of the fleet was treated the same in year #1. Stabil was mixed into E-10 gasoline and the fuel tanks were topped off after a brief run to fill carb and fuel system. In April, all of the equipment started easily and ran fine with the exception of one series of small (4 HP) Kawasaki engine. All eight of those had clogged fuel main jets. In following years, all equipment was treated the same as year #1 with the exception of the Kawasaki's. Those engines had the fuel system drained but not the tanks (steel). I wrote the clogged jets off as the way the carb fuel bowl was vented. There was enough air entering the bowl and the main jets had very small orifices.

[tpi]

On ATVs, generators, etc. I've always run the carb dry or drained it. Occasionally will make moderate term exception for products with gravity feed fuel flow where the bowl will not dry out.

Think in general, drain it, run it dry. Don't let gas sit in tank for a long time. Two strokes using premix seem to be less sensitive to these problems due to the oil residue.

[crcr]

alank2 wrote:
There certainly is not a general consensus about this!

Can we do a poll at this site?

Something like:

fuel off/carb empty
fuel off/carb full
fuel on/carb full

Add one more:
fuel left on/carb and tank empty.

I run it till it uses up the last of the fuel in the tank and dies. Then I leave the fuel tank cap off for a couple of days so any last drops of gasoline in the tank evaporate out. I leave it that way for months, then when I put gasoline in, it starts after a few pulls.

[MEXICOWANDERER]

Yeah like Trump or Hillary. Dodgers or Phillies. Patriots or Broncos. Consensus? I wish you the best of luck in your "poll".

[alank2]

There certainly is not a general consensus about this!

Can we do a poll at this site?

Something like:

fuel off/carb empty
fuel off/carb full
fuel on/carb full

[TomG2]

Kayteg1 wrote:
Teaspoon of fuel left will make less varnishes that several oz of fuel left with the bowl full.
And again, have been doing that for over 20 years and never had to take the bowl out yet.

It is not "the teaspoon" that can cause the problem. If the owner lets it run low on gasoline every time he shuts if down for a day, week, or month, multiple teaspoon are evaporated and the resulting deposits are left behind. End of the season, one teaspoon, not much residue.

[Kayteg1]

TomG2 wrote:
The problem that I see with the "Run her out" plan is that one is guaranteeing that a small amount of gasoline will be left to evaporate and leave a residue every time the engine is shut down this way. By keeping the bowl flooded, this won't happen. I am beginning to think that it is a crapshoot either way. We had construction equipment that sat for years at times. Sometimes they would roar to life like they were run just yesterday and other times require carburetor and fuel system cleaning before they would even sputter.

Teaspoon of fuel left will make less varnishes that several oz of fuel left with the bowl full.
And again, have been doing that for over 20 years and never had to take the bowl out yet.
On my boat I install fuel shut off valve just for the purpose and one time I skip the season. The boat having thank with 3/4" open vent started on 2 years old gasoline just fine.
Since there was no prime pump, it took some cranking to prime, or some gas poured into throttle, but other than that, never had a problem in 8 years of ownership.

[fj12ryder]

If you knew that the float bowl would remain flooded there wouldn't be much of an issue, but if it sits long enough it will evaporate, and therein lies the rub.

[TomG2]

The problem that I see with the "Run her out" plan is that one is guaranteeing that a small amount of gasoline will be left to evaporate and leave a residue every time the engine is shut down this way. By keeping the bowl flooded, this won't happen. I am beginning to think that it is a crapshoot either way. We had construction equipment that sat for years at times. Sometimes they would roar to life like they were run just yesterday and other times require carburetor and fuel system cleaning before they would even sputter.

[westend]

Drain or run the fuel bowl dry on the carb. Turn the fuel petcock/switch to "off". If the float is sticking or the engine is hard to start, remove the carburetor, clean it, and install. Observe the float relationship to the pin and hinge it uses. Rarely, but it does happen that the float will stick.

[Sam_Spade]

alank2 wrote:

Sam Spade wrote:
Answer #2: There will be a little left but it isn't a little that you are worried about. The problem occurs when some evaporates and is replaced by more which then evaporates and is replaced........

Thanks Sam - what environment causes this?

Any engine with a vented carb (almost all) and a gravity feed gas line WITHOUT a shut-off......or the shut-off left open.

Gas evaporates pretty good down to about ZERO F or so.

It isn't nearly as likely to be a problem if there is a fuel pump OR if the gas tank is BELOW the carb.

Stabilizer still required though.

[alank2]

I guess I am calling a fuel petcock and fuel switch!! 🙂

[joebedford]

Just curious - what is a "fuel switch"? My generators have ignition / start switches and fuel petcocks but I've never heard of a "fuel switch".

[lc0338]

alank2 wrote:
lc0338 - Do you turn off the fuel switch?

Nope.. do not turn off the fuel switch.