RV Generator POPS after shut down

[oldjohnt]

Okay, I had no choice as to the existing equipment when I purchased my RV, but it came equipped with a Generac 4700 4 KW Generator. After I installed a new carb and starter solenoid and ever since it starts and runs sweet n smooth just fine. There is NO black smoke nor the smell of gas or over rich running and the plug has that nice warm gray coating IE she's NOT running over rich in my opinion. HOWEVER every time its used for any extended time (runs perfect mind you) about 3 or 4 minutes after shut down IT MAKES A SINGLE LOUD POP like a small inner muffler explosion or something?????????? I though over rich operation might leave gas in the muffler which can explode, but again with clear exhaust, no black smoke, no rich smell and a warm gray plug I just don't think its running rich, BUT WHATS WITH THAT DARN POP AFTER EACH OPERATION ??????????????????

 

 An ever curious John T

[gjhunter01]

 

Quote

 

How do you shut it down? Do you let it idle for a minute, do you use the cutoff switch, or do you cut off the fuel supply. If you use the cutoff switch which is OK, the engine would cycle a couple of times drawing in more fuel which would collect in the muffler. This might explain the back fire effect which is usually not a problem. Try cutting off the fuel supply for a shut down method.

Greg

[oldjohnt]

Thanks, I do the normal push the rocker switch to the OFF and as soon as I touch it she dies (don't have to hold it in OFF). To somehow turn off the gas (kill elec fuel pump) but leave ignition hot and let her starve out, I'd probably have to go outside each time YUK lol   My guess is when I touch the rocker to OFF it kills the ignition instantly and for sure it kills the elec fuel pump (of course still some gas in the carbs bowl).  I always let her run unloaded for a bit for cool down before I push the OFF. As good as it starts n runs I guess I wont worry but just curious as my Onans didn't do that.

 John T 

[Yarome]

That's a very well known issue with the Generac's and Greg is correct... post shut down excess fuel in the muffler ignition. Not much way around it unless you do a fuel shut off.

No harm done. Camp on!

[oldjohnt]

My normal luck lol This is my first GENERAC, but hey as good as it start n runs and can power the AC no problem if absolutely needed for a short cool down stint under hot dry camp conditions I'm GONNA CAMP ON  let her POP then, see if I care...............

 

John T

[mptjelgin]

3 or 4 minutes after shutdown??  I've heard motors pop 3 or 4 seconds after shutdown, but not minutes!  I think I'd have forgotten about the generator by then and be really startled.

[Yarome]

36 minutes ago, oldjohnt said:

My normal luck lol

Oh.. I dunno. Nothing really "wrong" with it.. just a little "quirky". I'm not in the least bit suprised "quirky" would end up in your camp. 

(meant as a compliment)

[oscarvan]

It keeps the squirrels away no?

[Ray,IN]

John, allow the genset to run 3-5 minutes after removing all loads, might not help but that's the Onan recommendation. I do however think your assessment is correct; fuel in muffler. The Honda engine on my ZTR mower does that if I forget to idle the engine for 3 minutes or more, it never smokes or smells of unburned gas either.

[oldjohnt]

 Ray, I try to let it run unloaded for a cool off before shutdown but SWMBO isn't as good at that lol. Actually, if I'm dry camping I like to run it maybe 20 to 30 minutes in the morning after making coffee etc. to power my 80 amp Smart Charger so my 450 Amp Hr battery bank gets off to a good start before the sun comes up and the solar kicks in. I may be adding yet another 235 solar watts (will take me up to 705 watts total) because I prefer to dry camp in the shade where you obviously don't harvest as much energy.

 Take care neighbor and Happy Easter

John T (Kirksville, Indiana USA)

,

[Pat & Pete]

That late pop should be seen as an asset .

Not only a warning to squirrels and such , but any ne'er-do-wells in the area might just think it's you target practicing .