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 > Help! Onan 4K generator refuses to start and stay on

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pnichols

The Other California

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Posted: 05/21/21 10:45am Link  |  Quote  |  Print  |  Notify Moderator

Ron ... I'm wondering if the same aging gasoline chemistry issue that causes Onan carbs to gunk up can also cause Onan fuel pumps and filters to gunk up?

To maybe help prevent the above, perhaps we should add the red-colored gasoline maintanier fluid in our motorhome's main gasoline tank for Onan generator protection. Just add a little bit of this fluid into the main tank whenever we gas up the motorhome - or a least add the fluid in the last tank of motorhome gas before we fire up the Onan a final time when camping - so that the Onan gasoline supply components wind up being exposed to treated gas from the motorhome's main fuel tank.

(We're fortunate in that we store our motorhome at home and outside. It's in a rural area, so we can run the Onan generator about once a month to keep it's gasoline components flushed out with somewhat fresh gas from the big chassis tank ... without bothering any neighbors.)

* This post was edited 05/21/21 12:49pm by pnichols *


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bobndot

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Posted: 05/21/21 11:18am Link  |  Quote  |  Print  |  Notify Moderator

Quote:



To maybe help prevent the above, perhaps we should add the red-colored gasoline maintanier fluid in our motorhome's main gasoline tank for Onan generator protection.


I always thought thats what most people do. Anytime i add treatment to any gasoline , I start it up to run it thru the lines of whatever that fuel tank runs.

Dusty R

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Posted: 05/21/21 03:21pm Link  |  Quote  |  Print  |  Notify Moderator

If you can get to the fuel pump add a switch to it and when you are not going to run the generator for a while, start it let it warm up then turn the fuel pump off and let it run out of gas, which completely empties the carburetor so there is nothing in it to gum up.

JaxDad

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Posted: 05/21/21 06:29pm Link  |  Quote  |  Print  |  Notify Moderator

pnichols wrote:

Ron ... I'm wondering if the same aging gasoline chemistry issue that causes Onan carbs to gunk up can also cause Onan fuel pumps and filters to gunk up?


People giggle when I fill up with premium gas, “You idiot, it only needs regular, you’re throwing away money!”.

Maybe, but premium is ethanol free and neither of my Onan’s have given me a lick of problems in 10 (for one) and 15 (for the other) years despite not being started sometimes for a year at a time.

No ethanol, no problems.

Oh, BTW, it doesn’t cost more, my increased mileage more than covers the per gallon difference.

pnichols

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Posted: 05/21/21 07:12pm Link  |  Quote  |  Print  |  Notify Moderator

JaxDad wrote:

pnichols wrote:

Ron ... I'm wondering if the same aging gasoline chemistry issue that causes Onan carbs to gunk up can also cause Onan fuel pumps and filters to gunk up?


People giggle when I fill up with premium gas, “You idiot, it only needs regular, you’re throwing away money!”.

Maybe, but premium is ethanol free and neither of my Onan’s have given me a lick of problems in 10 (for one) and 15 (for the other) years despite not being started sometimes for a year at a time.

No ethanol, no problems.

Oh, BTW, it doesn’t cost more, my increased mileage more than covers the per gallon difference.


Hmmm ... I wasn't aware that premium grade gasoline is exempt from requiring refiners to add ethanol to it in the states that require a certain percentage of ethanol be in gasoline in order to meet clean air environmental requirements.

Is there a website where we can check ethanol in gasoline requirements for each state ... or are they now included in federal clean air regulations?

whemme

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Posted: 05/21/21 09:30pm Link  |  Quote  |  Print  |  Notify Moderator

JaxDad,

In most states 10% ethanol is also added to premium gas. Secondly, for vehicles calling for the use of 87 octane regular gas, using premium fuel absolutely will not increase your mileage. Premium fuel also is not any ‘cleaner’ than regular fuel that some believe. The only difference in the two fuels is the higher octane (anti-knock) rating and the approximately $0.60/gallon extra cost that you are just wasting using premium.

* This post was edited 05/22/21 12:48pm by whemme *


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Gjac

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Posted: 05/23/21 07:56am Link  |  Quote  |  Print  |  Notify Moderator

What I do is add a 1/2 can of Seafoam in a gallon can when ever it runs rough then draw from that can instead of the main tank and exercise the genset under load for an hr. My genset rarely gets used and I have to look for ways to use it rather than exercise it for an hr each month. Two other things I would try is whenever it shuts down while it is still hot, check the spark I have had to replace my coil because it would not work when it got hot. The other thing to check does the fuel pump still pump gas when it shuts down. I had a loose hose clamp on top of the main tank than was loose, sometimes it would pump fuel and sometimes it would not. I ended up replacing the rubber line because it was 25 years old sometimes they can leak air due to age. Good luck.

JaxDad

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Posted: 05/23/21 03:31pm Link  |  Quote  |  Print  |  Notify Moderator

whemme wrote:

JaxDad,

In most states 10% ethanol is also added to premium gas. Secondly, for vehicles calling for the use of 87 octane regular gas, using premium fuel absolutely will not increase your mileage. Premium fuel also is not any ‘cleaner’ than regular fuel that some believe. The only difference in the two fuels is the higher octane (anti-knock) rating and the approximately $0.60/gallon extra cost that you are just wasting using premium.


I beg to differ sir, I have physically checked my mileage MANY times running both ethanol enriched and ethanol free gasoline.

My mileage increases about 23% by running ethanol-free fuel.

So here’s how that plays out in my case, round-trip to south Florida is about 3,000 miles.

My rig gets 7.32 mpg on regular gasoline with ethanol in it. So that trip is 410 gallons. If it has 10% ethanol then it’s 41 gallons of ethanol and 369 gallons of gasoline.

On ethanol-free premium my rig gets 9.0 mpg. That same trip then uses 334 gallons of only gasoline.

If your $0.60 / gallon is close then that trip costs an ‘extra’ $200. Except I bought 76 less gallons of gas. If we use a $3 / gallon average price that is $228.

So if I ‘waste’ $200 on premium but spend $228 LESS in fuel, it looks to me like I’m up $28....... and that’s before we get into the 35 gallons less gasoline and 41 gallons of ethanol I DIDN’T burn on top of the 334 gallons of ethanol free gas.

The only thing the current ethanol-enriched gasoline is doing is wasting food, making corn industry folks richer and making social media folks feel good.

whemme

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Posted: 05/23/21 04:26pm Link  |  Quote  |  Print  |  Notify Moderator

First I was referring to both premium and regular fuels both containing 10% ethanol. Fuels (both regular and premium) containing 10% ethanol have about 3.3% less energy (BTU’s) than fuels without ethanol. You can lookup the BTU energy contend on both types of fuel on the internet. By the way premium fuel contains the same energy content as does regular fuel. So you should see only a 3.3% mileage increase using ethanol free fuel - not 23%. If you are seeing a 23% increase you are somehow creating extra energy and you should patent your process.

Grit dog

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Posted: 05/23/21 04:54pm Link  |  Quote  |  Print  |  Notify Moderator

^Bingo. 23% fuel mileage increase is greatly overstated I believe.
And has nothing to do with the OPs post and query.


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