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Fuel problem?
https://www.slantsix.org/forum/viewtopic.php?t=17585		 Page 1 of 1
Author:  slanted6 [ Tue May 16, 2006 7:26 am ]
Post subject:  Fuel problem?
Added a bottle of "Heet" Saturday, fuel gauge indicated about a quarter of a tank. Fueled up yesterday afternoon at my regular fill up spot. A few miles after this the good old reliable slant started to miss. Pulled the choke out most of the way and was able to do about 50 mph. Running close on time, so I went ahead and drove it to work. Left work this morning and things were fine till I tried to get up to speed. Repeat of yesterday's experience. Did I goof by putting the "Heet" in and letting the vehicle sit? Had a similar problem after overhauling the vehicle. Put a small amount of fresh fuel in tank and started it up. Ran fine until it got under load. Thought I had a defective fuel pump, replaced pump, same problem. Pumped tank empty and put fresh fuel in, no problems.
Author:  SlantSixDan [ Tue May 16, 2006 9:14 am ]
Post subject: 
"Heet" is alcohol sold as gasoline line anti-freeze. Why'd you add it...?

Alcohol tends to pick up water and trash in the tank and sweep it through the system, inundating both fuel filters and sometimes dragging cråp into the carb.
Author:  KBB_of_TMC [ Wed May 17, 2006 10:16 am ]
Post subject:  dry gas
I'm from Michigan; if you didn't add dry gas once in a while, you could find yourself with ice blocking your fuel line. I only added 1 bottle about 2X year as cheap insurance and never froze a line; I've done it for 20 years. Now that I can only get gasohol around here, I may stop doing it.

I find it odd that 2% dry gas (methyl or isopropyl alcohol) could cause your problems unless your gas had lots (15%) of (possibly damp) MTBE or you have damp (0.3% water) (E10) gasohol, or, if you're carb is using an ancient (non-Viton) float valve or really, really, old rubber components.

These two fuels are not very compatible with each other. They also are can cause certain rubber compounds to swell or degrade. I seem to remember that Buna-N, a very common material for O-rings for example, will swell ~50% in ethanol, but shrinks back when it dries out.

The chemistry of the reformulated gasolines is quite different what the old gasolines; I'm not sure what adding dry gas to damp RFGs would do - seperation is a complex azeotrope of water, ethanol or MTBE, benzine, and other stuff.

Roughly, gasohol will hold 40X more water than the old gasoline.

If you take a sample of your fuel, add ~2% Heet to it, you should see if seperation is a problem. If not, I'd check the condition and consider replacing any rubber components in the fuel line that are 30+ years old.

I'd also suggest replacing the fuel filter and looking inside the old one for obvious debris.
Author:  SlantSixDan [ Wed May 17, 2006 10:39 am ]
Post subject:  Re: dry gas
Quote:
I'm from Michigan; if you didn't add dry gas once in a while, you could find yourself with ice blocking your fuel line.
Not in May, you can't! :shock:
Quote:
I only added 1 bottle about 2X year as cheap insurance and never froze a line
I lived in Michigan, and in Denver, and now in Ontario. In my whole, entire life, I've added zero bottles of alcohol ("dry gas", "heet", etc.) to zero of my vehicles, zero times a year, and never froze a line, either. This is not 1963 we're living in. Gasoline formulations aren't what they used to be. That they even still advertise "dry gas" is more or less a scam. Those who live where it gets really cold (most of Michigan, heck, most of the USA and most of where people actually live in Canada doesn't count) and who live where the gasoline supply is of questionable reliability, may still have a valid reason to pour some isopropyl alcohol in their gas tank on rare occasion.
Quote:
I find it odd that 2% dry gas (methyl or isopropyl alcohol) could cause your problems
Any amount of methyl alcohol (methanol) can cause extreme problems in the fuel system. None of the materials are meant to tolerate it.
Quote:
Buna-N, a very common material for O-rings for example, will swell ~50% in ethanol, but shrinks back when it dries out.
Yep. Problem is, when the rubber components swell and soften in the alcohol, they often get cut or torn or deformed by whatever they're seated against, and then when they shrink back down, there are leaks due to the new damage.
Author:  KBB_of_TMC [ Thu May 18, 2006 10:24 am ]
Post subject:  dry gas
Hi Dan,

I completely agree that dry gas may not be very useful now with oxygenated fuels, but my wife (while in NC) has had frozen fuel lines in the past - I suspect the problem is much worse where the temperature swings through the freezing point often, rather than where it stays well below freezing; similar to the rust belt distribution maps.

I've also used deer whistles for years as cheap insurance - I've hit no deer nor elephants - but that doesn't prove much of anything. I have run dry gas 2X/year for probably a total of 200,000 miles over a period of 30 years, and when I've taken the carbs apart I've never found any indication that the dry gas hurt anything. My averge dry gas concentration works out to something like 0.04%.

To get back to the origonal question - Note that slanted6 added the dry gas to about a 1/4 tank (~2% = 4X normal concentration) and didn't report a problem. THEN he filled up with gas and THEN had the problem.

It could have been an unusual fuel seperation triggered by the dry gas; however, it would require very special circumstances and probably a lot of water in the system. Much more likely, there was a problem in the batch of fuel and the dry gas had nothing at all to do with it.

Last month (I seem to remember it was Arco?) stations had to recall their gasohol due to water contamination - people "weren't getting very far" from the station before their cars quit.

I'm doing some long term tests on the gasohol around here for seperation and corrosion; eventually, I'll be putting some typical additives into the samples to see if anything unusual happens.
I'll let you know what I find.
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