<div dir="ltr">Diesel fuel goes bad over time. Just like gasoline the fuel is not stable. There are ways to test it but to my knowledge it means sending a sample to a lab. Besides sludge and solids accumulating there's some green mold/fungus that grows in it. They make fuel conditioner with biocide to make it last longer but a "few years" is longer than any of them would say they would protect fuel. Your symptom sounds like a plugged fuel filter. If you don't have a water separator and fuel filter on your tank I'd add those and change the filter on your tractor. Get good filters rated for the lowest particle size you can. Injector tolerances and tiny and even very small particles will cause them to fail. Ag equipment isn't designed to as tight a tolerance as on-highway because they didn't have to meet the strict emissions standards as early, but skimping on filter costs will result in much higher costs in repairs. On of my favorite lines from some Triumph shop manuals starts "It is false economy to reuse (some part I don't remember)" So paraphrasing... "It is false economy to use cheap fuel filters on a diesel engine."<div><br></div><div>Regarding using the old fuel it all depends on how much you want to spend on filters and repairs versus disposing of the $150 worth of diesel you've got in the tank. The rule of thumb is to not have more than six months supply on hand. Older engines will be more tolerant of it than later (last 10-15 years) engines. That's why the guys that were cooking their own biodiesel from french fry oil wanted engines from before the 90s.</div><div><br></div><div><br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div>Ben Zwissler<br></div><a href="mailto:bjzwissler@gmail.com" target="_blank">bjzwissler@gmail.com</a><br></div><div>812-343-5533</div>Columbus, IN<br></div></div></div></div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Apr 24, 2020 at 7:46 AM eric--- via Shop-talk <<a href="mailto:shop-talk@autox.team.net">shop-talk@autox.team.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><font size="2" face="sans-serif">Does anyone know of a way to tell if diesel
fuel has gone bad?</font>
<br>
<br><font size="2" face="sans-serif">Here is my situation. I have a
large diesel fuel tank for my tractors on my property (so I don't have
to buy 'over the road' diesel.) The fuel in there has been there
a few years.</font>
<br>
<br><font size="2" face="sans-serif">My newest tractor (a small 25hp subcompact)
started acting funny. At full throttle, it seems to sputter a little.</font>
<br>
<br><font size="2" face="sans-serif">Could be a fuel problem, but I would
love to test the diesel somehow. Or is there a way of looking at the filter
on the tractor? Or another test to do?</font>
<br>
<br><font size="2" face="sans-serif">Related follow up, if the fuel is bad,
and I have about 50 gals in a 250 tank. Can I just add fresh fuel
to it, or do I need to drain out all the bad first? What would be
a good bad/good ratio to dilute the bad fuel?</font>
<br>
<br><font size="2" face="sans-serif">Thanks!</font>
<br><font size="2" face="sans-serif"><br>
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