Is it just me, or is gas cruddy these days? I normally turn off the fuel petcock and let the generator run out of gas before I shut it down. However, I decided to just shut it down by turning the petcock, then the generator switch without waiting until it dies. Came back five days later... the generator was extremely hard to start, but I managed to get it going.Lesson learned... let the genset run the bowl dry.My question is... once I get a motorhome with an Onan generator, will this be as big an issue? Should I install a fuel petcock on the generator's fuel line, so when it is time to shut it off for a while, I can turn it off at the petcock, let the carb bowl run dry?

If this were my unit (an Onan 4000) I know from experience it would be because the choke was stuck in full open.

I have a 1996 Southwind with the original Onan 5500 generator.It does not have a peacock to shut off the fuel. I run the generator every 4-6 weeks under a load. It always starts without a problem. I don't think it is necessary to install a shut of on the fuel line.

Not sure which generator you are having issues with but our Onan has been 100% problem free, even has the original fuel filter although I have a couple of spares. I use the cheapest gas I can find as with all my motorized equipment (including vehicles) and have never run any of them dry. Both my onboard Onan and Champion 3100 inverter genny are just turned off and on as needed, never a carb issue with the Onan going on 10 years using 85/86 octane ethanol gas. I know many have had issues using such gas, my experience indicates this isn't related to just cheap fuel. For the Onan I always add a bit of Stabil when refueling and maybe couple times a year a can of Seafoam. With the Champion since the fuel tank is pretty small I don't add Stabil but I do add a small amount of Seafoam to the 5 gallon gas can I use. Our rig goes pretty much unused for 4 months during the winter season and never an issue with the old stale gas, just prime the Onan for 30 seconds and she cranks up fine. In fact that reminds me to go out there and give her a little exercise while I'm thinking about it. Hope whatever is plaguing your genny is minor.

gas siting for five daysnot the problem but thats just my opinion, gas sits in my boats ,three motors for weeks at a time and fire right up.

My 2KW Honda would sometimes be hard to start after sitting for three or four months in my garage. Then I started keeping it secured in the tailgate corner of my covered truck bed and it now starts on first or second pull of the cord. I guess the constant sloshing around of the fuel keeps all the crud cleaned up somewhat... I too keep some Seafoam in my 5-gallon gas tank for the mowers and portable genset...Roy Ken

Let fuel sit in a carb bowl for five days -- very hard start

16 Replies

SaltiDawg
Explorer
Mar 01, 2017
After five days?
down_home
Explorer II
Mar 01, 2017
A lot of hard start after sitting, is the gas evaporates and drains back into the tank too.It goes right though the air filter and even the manifold and valves, and you have an empty fuel bowl.
On injection engines still have same or similar problem the 35horse Kawaski on one, of my mowers and the 25 on my other one still take a bit to get fuel to the injectors. The push mower with carb has prime pump on the carb and starts easily after months.
The alcohol in the gas attacks brass steel and rubber and everything else via hydrogen embrittlement. One reason I buy more expensive no enthanol gas.
wa8yxm
Explorer III
Feb 28, 2017
That short a set time you should not have had hard start issues.

However with ONAN it is a carb engine, and the gasoline evaporates.. It takes time to replenish it in the bowl.. I think that is the issue.

My genny initially was hard to start.. Then I re-read the manual

Press and hold STOP till the light comes on (in fact keep holding it for like 10 or 30 seconds) then press START.

Or, "Tap" start.. let it sit for about 30-60 seconds THEN Press start.

Either method seems to fire it up much faster.

Got to do that next week, Normally it would be tomorrow but I'm hoping to haul this "Shack" to the shop for an engine swap next week. So..... I'll only have minimim 120vac there.. Will need to "Augment"
ctilsie242
Explorer II
Feb 28, 2017
That makes sense. The causes and symptoms almost perfectly match what happens if the O-ring has issues.
fitznj
Explorer
Feb 28, 2017
Gas is not your problem. It's an issue with the small rubber(?) o-ring that sits
under float-bowl valve. Gas with ethanol will harden the o-ring over time and fuel will leak around the o-ring and flood you engine.

I've had this problem on motorcycles and weed-wackers - replace the o-ring with one made out of Vitron (?) and problem solved. Draining the float bowl temporarily solves the problem.
old_guy
Explorer
Feb 28, 2017
man where have you been the last 20 some years. ever since they went to ethanol gas, the gas has been getting bad and very hard on carburetors. I use non ethanol gas on all my small engines. it costs more but sure is worth it.
ctilsie242
Explorer II
Feb 27, 2017
The weird thing is that before and after that, it starts like normal. Open the petcock, wait 10-15 seconds, twist the starter for a few seconds, it is running. It was only that one time I had fuel in the bowl where I actually had it start with difficulty.

I wouldn't be surprised if there might be another issue... the generator, a 3000 watt Yamaha (3000 iSE, no battery boost) has over 2500 hours on it, and I've mainly done oil changes and other upkeep, as well as use a fuel preservative with each tankful.

Maybe I should change the fuel preservative from Star-Tron to something else.
westend
Explorer
Feb 27, 2017
Your generator has a coincident problem. If the fuel system is all operating correctly,the generator should start within that small time frame.

FWIW, I was the steward of 125 small engines that were seasonally stored for 6 months. In the Spring, all started and ran right except for one series of small Kawasaki engines. It was determined that the fuel-air mixture construction allowed the main jet to clog with oxidized fuel particles. Those Kawasaki engines were treated differently in following years.
turbojimmy
Explorer
Feb 27, 2017
Trackrig wrote:
The gas and five days isn't your problem, mine go for months without an issue.

Bill

Yep. Mine's been sitting since last October. No fuel shutoff. I run it (Onan 6500) once a month and it's fine every time.
Trackrig
Explorer II
Feb 27, 2017
The gas and five days isn't your problem, mine go for months without an issue.

Bill