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There's an epidemic problem with fuel these days, and many blame ethanol and winterized fuels as the culprit.  Whether ethanol or MTBE is the issue, carburetor and EFI system clogging is rampant, especially in vehicles that set for long periods of time.


This became clear when our XR350R Honda dirt motorcycle set for over a year with fuel in the carburetor bowls.  This four-valve thumper uses two carburetors, and one has the idle circuit and a pilot jet.  The engine ran flawless until parked, then would not idle after setting for a long time.


Most of us are aware of this plague, especially owners of Jeep 4x4s, rock crawlers and OHVs that park for long periods.  Essentially, gasoline and diesel fuel has a shelf life.  These fuels break down over time.  The result can be an inability to fire, severe engine ping and symptoms similar to extremely low octane performance. 


In the day, this would simply cause poor performance.  A fresh tank of fuel would solve the problem.  Remember that old barn find MB Jeep or Bultaco motorcycle that would not start?  A fresh tank of fuel (pre-mix for the Bultaco, please), priming the carburetor, and the engine fired!  Sure, the carburetor gaskets may have shrunk and they leak now, but we're running!


Today's ethanol behaves like alcohol and bonds with any water in the fuel. This water, instead of laying low in the fuel tank, moves through the fuel supply system.  Fuel filter materials, especially pleated paper, swell in the presence of water.  This swelling serves as a safeguard to protect fuel injection and carburetor components:  The filter clogs and stops fuel flow. 


Note: This can even happen from one bad tank of fuel (too much water content).  We've all heard about or experienced the gas station that ran its storage tank to the bottom, where the water accumulates.  The unlucky customers who pumped that gas wound up with clogged fuel filters.


Back to the XR350R example, the stale pump gas in the fuel bowl and pilot jet caused such severe clogging of the jet that the jet could not be cleaned with carburetor cleaner!  (Drilling a carburetor jet is a lost cause; the bit, even turned with finger tips, will scarf into the brass and increase the jet's bore size!)  I replaced the jet with the proper size pilot and rebuilt both carburetors.  The engine's dependability and performance immediately returned. 


So, if your 4x4, OHV, ATV or dirt motorcycle sets up for long periods, consider using a fuel stabilizer or other additives that will prevent fuel breakdown and damage from stagnant fuel.  In the case of motorcycles and ATVs with petcocks, always turn off the fuel for both safety reasons and to stop flow to the carburetor.  Drain the carburetor bowl(s) when your OHV or bike will set for long periods;  most OHV carburetors have a simple drain plug on the bottom of the carburetor's float bowl.  Don't overlook the "fuel station" on your toy hauler trailer, either!  Use up that fuel or stabilize it.


I keep stored fuel for no more than four or five months these days.  If my 4-stroke motorcycle fuel can is setting that long with fuel, the fuel gets dumped into the street/trail driven XJ Cherokee and burned up.  


We do the same with the Ram/Cummins diesel and its 75-gallon auxiliary fuel tank.  After 60-days without a lot of driving, I will run both tanks down completely, timing the refill for a period when fuel prices will not be devastating:  This is a 110 gallon refill, and the 30-50 cents a gallon "futures-based" price hike can be costly.


Does anyone have a gasoline or diesel fuel stabilizer that they find useful and effective?  Please share...



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Moses, i know it has been hyped in print, TV, and other media, but i have found that Stabil works better than they advertise. 3 years ago, in anticipation of a week's vacation on or near the water, i filled the gas tank in my old boat (a 1980s Bayliner), which is 20 gallons, only to find out a few days later that our annual family get away was being postponed, due to my wife finding us a new property to purchase, away from the city, for us to move to.


Between moving, remodeling, and other get aways and family functions, my boat sat with that same tank of fuel for 3 years. I did put Stabil in it the year i filled it, and then knew it was going to sit. This year, since i never use that boat anymore, due to buying a bigger boat plus jet-skis, i decided to sell that boat. I figured i would at least drain the old gas out, put fresh in it, just to get it running and make sure there were no engine issues.


I stored the old gas in 2 10 gallon gas cans, and then found out my wife had poured one of the cans into our around-home truck (a 1991 Dakota 4x4, with a 3.9l v-6), which we use for getting firewood and other non-pavement uses. That was 5 weeks ago, and the truck starts right up and seems to run with only a minor stumble here and there, which it already had before she put the old gas in it.


Im not recommending everyone do something like that, but Stabil does work well.

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I was advised yesterday that putting a small amount ( ie 16oz) of Dextron II or similar Automatic Transmission fluid into the gas tank of a Diesel engine ( Ford/Chevy/Dodge HD pickups)  is like a detergent and it helps clean everything and improves fuel efficency?  


Is this true???


Thanks, Joe Mac

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I can understand the impulse, as ATF is highly detergent and has lubricity.  On the other hand, the modern diesel injection systems, including your Duramax, are common rail or electronically pulsed, i.e., electronic fuel injectors.  These injectors are designed to flow fuel not "oil". 


With the absence of sulfur and other fuel "upgrades", there are already issues with O-ring life and such.  I would stick with an injector cleaner or fuel additive from Lucas and others, formulated for injectors, seals and other critical parts.  If "cleaning it up" meant internal engine or combustion chamber concerns, I'd consider a mild methanol or water injection system.  Considering the modern electronically controlled fuel flow, there should be no reason, however, for excessive soot or carbon buildup in your engine's cylinders.


Our Ram 3500 with the 5.9L Cummins H.O. engine has never suffered from a pump or injector issue in 123K miles.  I do change the fuel filter regularly, and in recent years switched to GDiesel fuel when affordable, which helps tremendously (even for cleaning the injectors and the engine).  Unfortunately, that formulation is limited to Nevada and Utah availability at present.  If you're curious about GDiesel, check out my coverage at the magazine: http://www.4wdmechanix.com/Performance-Diesel-Fuel-GDiesel.html.  This includes a product overview and HD video tour of the plant east of Reno/Sparks, Nevada.


Many of the home remedies for diesel injector clogging and such date to and reflect the mechanical injector era.  With a mechanical fuel injection system, close-tolerance parts issues and fuel clogging would be much more prevalent.  Also, the coking and soot buildup in a diesel would be more likely with an emissions exempt, off-highway diesel, though their cylinder and exhaust temperatures under load, in most cases, make carbon buildup unlikely...


I'd stick with commercially available fuel additives and injector cleaner formulated for your Duramax...Besides, who wants to stain their driveway or damage a paint finish by spilling ATF with red dye down a fender?



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