Bad Diesel - how to filter / purify it?

[California]

I have 25 gallons remaining of red (offroad, untaxed) Diesel that started giving me trouble as old fuel was exhausted and this became 100% of the fuel in use.

Engines lose power unexpectedly but if I get the clutch in quick enough then they gradually come back up to rpm. I don't hear a cylinder missing. If one stalls, cranking starts it instantly. Both my 2-cylinder and 3 cylinder Yanmars act the same so its definitely the fuel.

On each tractor, I suctioned the bottom of its fuel tank to remove anything blocking the outlet fitting, then opened the line down at the injector pump input and drained the system, so the fuel in that bucket had gone through the fuel filter. Blew out the lines and replaced the fuel filters. No water found.

Drained my bucket of bad fuel through a brass mesh coffee filter (it won't go through a paper Melita filter) and filtered out a small quantity of 'wool', sludge, and a noticeable quantity of particles. These tractors are 45 years old so debris isn't surprising, that's what the fuel filters are for.

Then I made a batch of 50% filtered fuel / 50% fresh diesel. That ran fine. Until I needed to refuel, and poured in my old filtered Diesel. Back to running crummy.

Is there some way to salvage this $100 of bad fuel? What is fuel 'polishing'?

 

[mrmikey]

Bet you're dealing with diesel bugs. Nothing going to help that but biocide and a good filtering as well as a good system cleaning. All that adding good diesel to it is you're contaminating the good fuel.

 

[MF243RedTop]

Yeah throw it on a burn pile ..that will purify and clean it ...
If you're going to keep diesel that long ...like mentioned look into biocide ...
The tank you're storing the diesel in needs to be drained, washed clean and treated with biocide before filling it back with fresh fuel.
Also some biocide in your tractors fuel tank won't hurt either ..it's contaminated now too
If you keep trying to save a buck and using that old fuel with growth it in...you may end up with problems in your injection pump ..
Toss it!

 

[alexpops]

fuel polishing is running through a filter. google youtube & you'll see some set-ups used by boaters where algae can be a big problem. A pump/cheap racor knockoff head/fittings/hose & lots of filter media is all it takes to make a diy polisher. upside is it's re-usable ... downside is parts will cost you about the same as the fuel you're trying to save this go round

 

[RjCorazza]

I have polished bad fuel in the past. Start with letting the fuel settle for a day or two and pour / pump off the top, leaving the few gallons at the bottom for a burn pile. Filter what you pumped off through a course filter like a "MrFunnel" water separating filter, then filter again through a Racor 2-5u water separating filter.
I would also treat it with a biocide, as well as ANY tank that had this fuel in it.

 

[Hay Dude]

Yeah throw it on a burn pile ..that will purify and clean it ...
If you're going to keep diesel that long ...like mentioned look into biocide ...
The tank you're storing the diesel in needs to be drained, washed clean and treated with biocide before filling it back with fresh fuel.
Also some biocide in your tractors fuel tank won't hurt either ..it's contaminated now too
If you keep trying to save a buck and using that old fuel with growth it in...you may end up with problems in your injection pump ..
Toss it!

Agree.
Saving $100 bucks worth of old fuel versus a real headache for injectors and injection pump????

Bless your little heart. lol

 

[woody]

What are yawl saying is a good biocide, may need to go ahead and do some treating while it's on my mind.

 

[dodge man]

If you had a 1000 gallons that’d be worth messing with but that small of amount I’d get rid of.

 

[California]

Thanks everybody for the comments.

Sounds like the next step is discarding this fuel, then cleaning the 5 gallon jugs with biocide.

What biocide?

 

[arto98607]

Biobor JF

Biobor JF biocide

 

[RayIN]

FWIW, one time I bought an old Case diesel tractor. It had been parked along a fence-row for so long I had to cut 2, 4"D trees growing up through the frame.
I winched it onto my trailer, brought it home. I drained the fuel tank, blew out the lines, replaced both fuel filters.
I took those 2 G buckets of fuel and after sitting overnight, I slowly poured the diesel off the water. Then I poured the fuel through an old dish towel, which caught some "stuff".
I poured that fuel back into the tank, installed a new battery, and after checking oil level, started the engine. I used that old Case around the farm until it required more fuel, so filled the tank and parked the tractor in my front yard with a for sale sign.
I sold that old Case for $1,800; not bad for buying it for $100_not running. Although it did take me half a day getting it out of that fence row.

 

[Hay Dude]

FWIW, one time I bought an old Case diesel tractor. It had been parked along a fence-row for so long I had to cut 2, 4"D trees growing up through the frame.
I winched it onto my trailer, brought it home. I drained the fuel tank, blew out the lines, replaced both fuel filters.
I took those 2 G buckets of fuel and after sitting overnight, I slowly poured the diesel off the water. Then I poured the fuel through an old dish towel, which caught some "stuff".
I poured that fuel back into the tank, installed a new battery, and after checking oil level, started the engine. I used that old Case around the farm until it required more fuel, so filled the tank and parked the tractor in my front yard with a for sale sign.
I sold that old Case for $1,800; not bad for buying it for $100_not running. Although it did take me half a day getting it out of that fence row.

The difference now is today’s injectors are like tiny computers with much higher pressure & finer plumes with smaller but more injector holes. .
In old tractor injectors, you could get away with poor quality fuels. Today, it’s got to be cleaner and free of water.

 

[California]

In old tractor injectors, you could get away with poor quality fuels. Today, it’s got to be cleaner and free of water.

That's good to know. My elderly Yanmars from the early 80's (see sig photo below) were made like an 8n, deigned so that nearly any repair could be done by the farmer. Neither has ever seen a pro mechanic while I have owned them. Bought used, 2003 and 2010.

Examples in the YM240 owner's manual: if run without a battery, turn on the lights to give the alternator a load. Fuel debris exceeding a tablespoon / 5 gallons may need more frequent fuel filter replacement. And the all-time classic: "Polish the injector orifices only with a birch stick lubricated with tallow".

My prior YM186D dyno tested meeting its horsepower spec at 30 years old. I haven't seen a need to replace these with anything new.

 

[Hay Dude]

That's good to know. My elderly Yanmars from the early 80's (see sig photo below) were made like an 8n, deigned so that nearly any repair could be done by the farmer. Neither has ever seen a pro mechanic while I have owned them. Bought used, 2003 and 2010.

Examples in the YM240 owner's manual: if run without a battery, turn on the lights to give the alternator a load. Fuel debris exceeding a tablespoon / 5 gallons may need more frequent fuel filter replacement. And the all-time classic: "Polish the injector orifices only with a birch stick lubricated with tallow".

My prior YM186D dyno tested meeting its horsepower spec at 30 years old. I haven't seen a need to replace these with anything new.

I still wouldn’t run old fuel with trash in it through an old diesel unless my life depended on it. Too much risk of problems.

 

[California]

Ok, I drained it all out. After adding biocide, Power Service Bio Kleen, at Shock concentration and sloshing everything around to clean the fuel tanks and fuel jugs. Per the instructions. Then treated the fuel filter assemblies and lines by draining a quart or so of the fuel down at the fuel pump inlets.

Then suctioned out the fuel tanks of both tractors. A surprising amount of crud came out. I had to blow out the little transfer pump a couple of times. The advice here to discard this bad fuel was the right thing to do.

Now I don't have an empty jug to go buy fresh diesel. I listed 'Free Bad Diesel' on Craigslist, "maybe use it in a wick-style shop heater". No takers so far.

First time in 20 years I've had bad fuel. I'll never buy Diesel at that station again!

 

[Quaffer]

First time in 20 years I've had bad fuel. I'll never buy Diesel at that station again!

Once in a while I look into the 5 gal containers of diesel I purchased locally at the pump. I can hardly believe the crap in the bottom .... I always filter even using pump fuel before pouring into a tractor.

 

[California]

Once in a while I look into the 5 gal containers of diesel I purchased locally at the pump. I can hardly believe the crap in the bottom .... I always filter even using pump fuel before pouring into a tractor.

Yeah. I always pour fuel into the Yanmar inlet strainer. Photo below.

I think the mess I have now is bacterial growth subsequent to filling the jugs in 2024. The blobs like black cotton in the strainer this week are new. And now there are some down at the real fuel filter. That gas station must have had a batch of bad Diesel.

Running 20 gallons of fuel polluted with this crud - even if the biocide had neutralized it - would have likely been bad for the injector system.

 

[California]

Bah. I offered this bad diesel on Craigslist. Two interested replies. Then both no-show without explanation.

Then no more replies. I may have to take it to the county hazardous waste facility.

 

[alexpops]

CalFire may take it to use for back burns come fire season

 

[arto98607]

Bah. I offered this bad diesel on Craigslist. Two interested replies. Then both no-show without explanation.

Then no more replies. I may have to take it to the county hazardous waste facility.

It makes excellent fire starter if you mix in just a little bit of gasoline.
Little bit of used motor oil too will not hurt but not necessary.

Takes a little bit of experimenting to get the best ratio of Diesel & gasoline.

IE.
Too much gasoline and it burns & lights too fast.

PS.
Very good wood preservative if you mix some Diesel fuel with used motor oil.