Phase Separated Gasoline

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I've been having issues with my MG running very poorly for about two weeks. After I'd exhausted all the "usual" troubleshooting someone suggested that I check the fuel pump for proper flow. It flowed fine, but the gas that I pumped into a clear glass bottle immediately separated into two layers.

Short of draining the tank, is there anything that I can do to salvage the current tank? Driving the gas off isn't really an option-I've only dared venture onto neighborhood roads as 25mph is about the fastest I can get it to go(in 2nd gear) on a flat road and I've been near stalling when going up a hill.

BTW, my records show that I last filled up on 7/24-it was a top off of a half full tank. It was premium from a top tier station that sells a decent amount of gas.
 
Without knowing the approximate percentages of the two layers, it's hard to say.

If you think one layer could be ethanol that separated out from the gas, and only about 10 - 20 % of the total volume, you might (repeat might) be able to make things somewhat better by adding the isopropanol version of gas line antifreeze, say around 1 - 2 quarts, and try that. I would go up and down a few hills or over a bumpy road in order to mix the contents of your gas tank better by getting it to slosh around.

Might not do anything, but then again, it just might.
 
Alright, I will drain it. That's what I was afraid of.

To be honest, I'm not sure how this happened. This is not a daily driver by any means and admittedly I didn't drive it a lot in July(busy with work and high humidity tends to make me want A/C) but in general I put 3K miles or so a year on it and also drive it to work once or twice a week. It was down most of May and June when a head swap turned into a lot more work than I expected, but I did put 200 miles or so on it toward the end of July.
 
Originally Posted By: Donald
Nothing can be done. Dump the gas, and change the filter.

You have to have a lot of water for phase separation. It's uncommon and almost always in boats.


^This

I work on OPE and see this almost daily. Keep gas tank full when stored or if it will be sitting awhile. Temperature changes cause gas tanks to breath in moisture, reason for full tank. Use ethanol-free gas if possible. Use Sta-bil 360 Marine Formula.
 
In Canada we used to have a problem with gas lines freezing with the onset of winter. Presumably there was some water in the gas tank. I haven't seen a frozen gas line in more than 30 years so something has changed. Maybe sealed gas tanks? better distributors? something in the gas?

In any case if you had a frozen gas line, a few ounces of methyl alcohol would solve the problem almost immediately. I still carry a small bottle of methyl alcohol when going onto the prairie in winter.

I assume the alcohol would melt the ice and soak up any additional water and the compound would eventually burn off. It never seemed to hurt anything. Of course if there was a lot of water, it might not work at all or it would take a lot of methyl alcohol.

So I'd be tempted to add a bit of methyl alcohol and see if that helps.
 
BTW, as far as using ethanol free goes:

The only local source I have only sells 87 octane. This engine is not stock(it has a 9.5:1 CR) and I find it difficult to tune out pinging without sacrificing performance with 87 octane. I actually should say that I have to pull the timing to the point where I do noticeably lose performance with 87 octane.

I have run 100LL in the past, but having just done a valve job(with hardened seats) I'm not inclined to lead up the engine again.

So, I'll get some gas cans lined up and proceed to drain. Fortunately, I can siphon it out easily enough either at the fuel filler or at the line going to the pump. I COULD let the fuel pump pull it out, but I also don't know what this junk might do to the diaphragm in my pump(this is a new production electronic SU pump, and it was not inexpensive). I have a new filter ready here.

BTW, I'm also considering just biting the bullet and putting a new tank in the car. There are no PRESSING issues with the current one aside from the bad tank of gas in it, but I figure a new tank once every 50 years can't hurt. I can get a new 13.5gal baffled stainless steel tank(the original is-I think-10 imperial gallons and is not baffled) for $150.
 
So if I have a bunch of gas that suffered phase separation, could I reuse the lighter top portion of the fuel in something like a lawn mower, or something that is tolerant of poor quality gas ?
 
Originally Posted By: philipp10
I would not call that "phase separation". Looks like water in your gas....period.


Correct.

Phase separation is not your problem, condensation most CERTAINLY is your problem.
 
On another note,
just the bottom 10-15% of the fuel in the tank is bad.
Keep the top 85-90% and dump it in another vehicle.
 
Originally Posted By: rubberchicken
So if I have a bunch of gas that suffered phase separation, could I reuse the lighter top portion of the fuel in something like a lawn mower, or something that is tolerant of poor quality gas ?


A lawnmower isn't very tolerant, but adding it to any modern EFI engine will burn it just fine.
 
Originally Posted By: SilverFusion2010
I would flare it off somehow. Start a campfire with it maybe


I'd use it to kill weeds.

Or run it through my lawn mower if I could filter it.
 
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