Generator smells of gas after turning it off

[Satman]

Has anyone else had this issue on the cumins 5500 geny. Seems if we run it for long periods of time and then shut it down you get a raw gas smell if your sitting outside. Also smelled it one night in bed above the geny. Another thing I noticed is that if you run it for long periods and shut it down it is very hard starting if you try to fire it right back up again, but if you wait a half hour or longer it's fine.

[Bulldog80]

Satman, Mine does this too. I've got it in the service department now getting some other stuff done. Did you ever diagnose this?

[Humermom]

We r having this problem in our new 2014 voltage 3905. It smells in the bed area which is above the generator after we turn off the generator. Anyone have any info on cause or service needed? Help

[macman83]

I wonder how you are shutting down the generator. It has always been my experience that you should unload it (turn off everything but the lights) and let it run for 5 minutes to cool down. This will set the throttle lower and clear out any excess fuel mixture that might linger in the intake. If its running under load and you just shut it down, the high throttle setting will dump a load of raw fuel into the intake, and since the sparkplug is not burning it, the fuel will be blown back into the air filter and then evaporate from there causing the smell.

[Bulldog80]

macman how are you supposed to unload a generator that's connected to the trailer? Go outside and flip the breakers on it? That's not necessary to do on these generators, nor do I believe has anything to do with the problem. They have an internal switch that loads it after starting and unloads it before shut off. I don't see how there's anything else you could realistically do?

[Wanderer]

Unloading it means turning off all the appliances that are connected and running it without putting a "load" on the generator portion. You should be able to hear it idling down as the load decreases.

His suggestion of running it to cool down after long periods is valid. I believe his rationale for the fumes is correct.

[Bulldog80]

You can't "unload" a generator that is always hooked up to an inverter that is constantly charging a 12v system whether you have something turned on or not. Yes, it would push a heavier load with an appliance running, but no matter what there is a draw on the generator.

[Wanderer]

Originally Posted by Bulldog80

You can't "unload" a generator that is always hooked up to an inverter that is constantly charging a 12v system whether you have something turned on or not. Yes, it would push a heavier load with an appliance running, but no matter what there is a draw on the generator.

That is true but if the generator had been running for some time the converter would not be in a high charging state therefore would not be using much power. By unloading we are referring to big loads like the fridge, TV or other high demand items (or a combination of a bunch of little things). You don't have to totally unload the generator, just enough that it throttles down to it's lowest idle speed.

[macman83]

That is what I am talking about. No need to flip breakers, just turn off A/C, microwave, space heaters, hair dryers, air compressors and such. Anything using 110 volts AC that is a big load. The RPM of the genset will not change much, but it will throttle down. For a visual, pull the air filter off of a portable generator. Run it with a load like a hair dryer and a toaster or coffeemaker. Turn it off with the load there and you will see it spit fuel back out of the carb. Run it unloaded and switch it off. You will hear and see a difference in the throttle, and see much less fuel come out on shutdown.

That is only one possibility for the fuel smell at shutdown, and can be easily checked, just try it and see if the smell goes away.

This is just my experience, yours may vary.