Removing possible fuel varnishing ( maybe ) after storage

[Nomore9-5]

I'm reaching out to you guys but hoping I don't have an issue when I restart the motorhome when spring finally gets here.
Mid - late October I started winterizing our mh .In addition to other things I added Stabil ( brand) fuel stabilizer to the gas tank ,filled it full and ran both the engine and generator .
The problem is the fuel stabilizer container was awkward to use and I had a lot of difficulty getting all the stabilizer in. So while I've got fingers crossed everything is ok I'm wondering if it makes sense to add some fuel treatment when the time comes (Berryman Chemtool advertises that their fuel additive gets rid of varnish ) .

Has anyone out there run accross this situation and can comment on this?

[BehindBars]

I wouldn’t worry about the fuel injected main engine. The gasoline generator, if carbureted, would be my concern. If it runs OK now, that’s great, but if not you can try the snake oils to clean it out, or disassemble the carburetor and clean it.

In the future I would have a fuel shut off valve on the generator, and if you anticipate a period of a few weeks where it won’t be run, close the fuel valve and run it ‘til it runs out of gas. I never leave gasoline in a carburetor for long periods, and thus have no varnish problems with them.

[njfishing]

Yep the carb in the generator would be my main concern. If it surges up and down at the higher rpm levels its likely starving for fuel which is likely the result of a gummed up carburetor. If your handy and can get at the carb they’re usually fairly easy to clean up. Take off the bowl make sure your needle valve seat is free of any junk and then clean out the jets. That usually solves these sort of issues.

[Nomore9-5]

Originally Posted by BehindBars

I wouldn’t worry about the fuel injected main engine. The gasoline generator, if carbureted, would be my concern. If it runs OK now, that’s great, but if not you can try the snake oils to clean it out, or disassemble the carburetor and clean it.

In the future I would have a fuel shut off valve on the generator, and if you anticipate a period of a few weeks where it won’t be run, close the fuel valve and run it ‘til it runs out of gas. I never leave gasoline in a carburetor for long periods, and thus have no varnish problems with them.

Great idea about turning off fuel valve for generator . I did it with lawnmowers in the past but never thought about it for this. I'll have a look in the Onan manual and see if I can locate where it is.
I also had no idea the engine had fuel injectors - I assumed it had standard spark plugs etc.

[Nomore9-5]

Originally Posted by njfishing

Yep the carb in the generator would be my main concern. If it surges up and down at the higher rpm levels its likely starving for fuel which is likely the result of a gummed up carburetor. If your handy and can get at the carb they’re usually fairly easy to clean up. Take off the bowl make sure your needle valve seat is free of any junk and then clean out the jets. That usually solves these sort of issues.

Ok thanks when I start it in the spring I'll see if it runs up and down like you described . If that's the case I'll see if a local Onan guy can clean it up.
Between now and spring I'll do as much reading as I can on carbs so I can try doing it myself.

[BehindBars]

Originally Posted by Nomore9-5

Great idea about turning off fuel valve for generator . I did it with lawnmowers in the past but never thought about it for this. I'll have a look in the Onan manual and see if I can locate where it is.
I also had no idea the engine had fuel injectors - I assumed it had standard spark plugs etc.

On my 4000 watt Onan generator, I had to install the fuel valve myself, in the 1/4” fuel line feeding the generator. Another option for me was to put a switch on the generator’s electric fuel pump and just kill the pump and let the engine run until it died.

I’ll have to look but I’m not sure if there is an easy way to just drain the carb bowl. That would probably be the best way.

[Nomore9-5]

Originally Posted by Nomore9-5

Great idea about turning off fuel valve for generator . I did it with lawnmowers in the past but never thought about it for this. I'll have a look in the Onan manual and see if I can locate where it is.
I also had no idea the engine had fuel injectors - I assumed it had standard spark plugs etc.

Meant to say carburerator .

[hobienick]

If you do have issues I highly reccomend Seafoam to clean things out. I have resurrected many outboards and lawnmowers with that stuff

[270S]

Thanks to Covid and all if that, I developed all the fuel problems in most of my vehicles. I've gone all the routes and products, but the one that truly worked, especially amazingly on the onan 5.5 and V10 was Berryman B12. It takes 5 cans to treat the F53 tank! Don't be cheap, it works!

I've treated multiple cars, multiple motorcycles, and the RV. Great stuff. Prevent the problem by running/using your engines. But even running won't help if the tank is still full from last year, the octane will drop considerably and require removal and replacement before treatment. This assumes that you keep a full tank. If it is around half full, filling it up with premium may bring the octane back to 87. Again, don't be cheap. The cost of repairs will far exceed the cost of this this solution. If this doesn't work for you, nothing will. This is not a paid endorsement.

[njfishing]

Originally Posted by hobienick

If you do have issues I highly reccomend Seafoam to clean things out. I have resurrected many outboards and lawnmowers with that stuff

Me too and the newer stuff also includes a fuel stabilizer which is good for up to 2 years.

I use in all my 2 and 4 stoke engines that get used seasonally...

https://www.amazon.com/Sea-Foam-Extr...s%2C168&sr=8-1

That being said, sometimes this stuff isn't enough and you'll need to clean the carburetor. The jets or the needle values gets clogged and your engine is not getting enough fuel. Typical symptoms are surging at higher RPMS or only being able to run the engine with the choke on..

[NJKris]

We in my Corvette club are no strangers to long term storage fuel issues. Besides using Stabil to put her to bed for the winter and never having any startup issues months later, we all swear by Chevron Techron Complete Fuel System Cleaner. Make sure it is the complete. I left some fuel in my Champion inverter generator a little too long (almost 2 months) and they were running poorly, surging. Brand new generators. Five minutes of running fuel with this stuff in it, it suddenly began purring like a kitten.

[Nomore9-5]

Originally Posted by BehindBars

On my 4000 watt Onan generator, I had to install the fuel valve myself, in the 1/4” fuel line feeding the generator. Another option for me was to put a switch on the generator’s electric fuel pump and just kill the pump and let the engine run until it died.

I’ll have to look but I’m not sure if there is an easy way to just drain the carb bowl. That would probably be the best way.

I've been doing a little online research . Looks like there might be a screw below the bowl that allows you to drain fuel . Also a reference made in generator owners manual too.
I'll have to wait until we're into warmer weather before I can be sure .

[NJKris]

The problem is the fuel stabilizer container was awkward to use and I had a lot of difficulty getting all the stabilizer in.

I stick a fuel fill adaptor that came with a gas can. Stick it in fuel fill on vehicle, then dumping the shots of Stabil into it is not awkward at all.

[Nomore9-5]

Originally Posted by 270S

Thanks to Covid and all if that, I developed all the fuel problems in most of my vehicles. I've gone all the routes and products, but the one that truly worked, especially amazingly on the onan 5.5 and V10 was Berryman B12. It takes 5 cans to treat the F53 tank! Don't be cheap, it works!

I've treated multiple cars, multiple motorcycles, and the RV. Great stuff. Prevent the problem by running/using your engines. But even running won't help if the tank is still full from last year, the octane will drop considerably and require removal and replacement before treatment. This assumes that you keep a full tank. If it is around half full, filling it up with premium may bring the octane back to 87. Again, don't be cheap. The cost of repairs will far exceed the cost of this this solution. If this doesn't work for you, nothing will. This is not a paid endorsement.

This somewhat confirms what I originaly thought I might do if I didn't get enough stabilizer in last fall. Unfortunately I filled the tank ( to prevent moisture getting in) so I can't add more ( new) gas . However it looks like Berryman also sells an octane booster so I may look at initially adding this as an alternate to the chemtool cleaner. Go on a roadtrip to get rid of say 1/2 the fuel . Add new gas . Repeat and this time adding the chemtool
Possibly overkill but may be the only way to be certain.

Might still use the Chemtool to clean generator carb . There's a u tube using Seafoam to clean it that I may try with the B12

[270S]

I tried Seafoam and all the rest. Berryman actually worked for me. Read and research before you use an octane booster. The side affects with the first treatment are irreversible. Spark plugs change color, .... I would remove gas from the tank first. I accidentally put 87 in my car requiring 93. I pumped the tank dry then refilled from a container. Don't cut corners. I have a fuel pump so it was easy, but there are other easy ways too.

[robo44]

If the RV is not to far from your home base and you don't mind going out once or twice a month you could start the generator under load for 1hr.

I do that with mine solves two problems, the potential stale gas in the generator and the Onanns are notorious if you don't run them once a month under load they mysteriously stop working or start to throw you codes and starting issues. Happened to me by not running the generator for 2 months. Thing was tossing codes and sputtering, Took running under a load (RV Furnace or AC) just to make it feel happy again.

[markb422]

Another reason to run the gen every month, especially in moist areas, is because the windings can corrode if not run under load (exercised) for a long time. They might start fine but the output might be lower than normal.

[rsdata]

while talking about fuel and additives, I want to share one of the best $10 investments I have made in a long time...

I stock five or six 5 gallon cans of fuel to tide me over if a significant power outage hits me like it has in years past. I try to rotate the gasoline yearly to keep it fresh, but this requires lifting and pouring and spilling a lot of fuel.

I purchased this device below and LOVE it... really works well when adding fuel to my small fishing boat fuel tank also... no more spills. It will drain a 5 gallon tank in about 2 minutes. Find it at walmart dot com

[Nomore9-5]

Originally Posted by 270S

I tried Seafoam and all the rest. Berryman actually worked for me. Read and research before you use an octane booster. The side affects with the first treatment are irreversible. Spark plugs change color, .... I would remove gas from the tank first. I accidentally put 87 in my car requiring 93. I pumped the tank dry then refilled from a container. Don't cut corners. I have a fuel pump so it was easy, but there are other easy ways too.

Since my last post I've been doing a little more research ( and in the process reading about nasty things like phase seperation in gasoline).It sure looks like the best approach is to pump out the old fuel that's there with something like in the pic you included and replace it with fresh gasoline as you suggest ( maybe with some B12) Perhaps you could send me details of the pump. I'm hoping the length of tubing will reach the bottom of the tank.
The tank holds 80 gal ( yikes) so there's going to be a few gas containers to go to hazardous waste facility !
Someone suggested I run the generator to keep it healthy - might also be a way of reducing what I have to pump.

[rsdata]

Perhaps you could send me details of the pump. I'm hoping the length of tubing will reach the bottom of the tank.

the pump works with an impeller at the bottom of the plastic thick part... without going out and measuring... it is long enough to reach the bottom of a 5 gallon gas can... it is powered by 2 D cells... I am guessing it is 18 inches reach from the bottom to the T-shaped hose outlet, which then reaches another 3 feet or so for an outlet spout... it sucks from the bottom and outputs thru the hose at the top...

after re-reading your initial post... I would NOT worry about phase separation on just a 6-7 month FULL tank of gas... not enough room for water vapor to sweat into the tank and contaminate further the fuel...