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Tank Varnish Contaminating New Gas?
Posted by: JP_REX ()
Date: March 19, 2017 04:06PM

Hi Everyone,
This is a little OT since the problem is with an MG Midget, but I think it is quite relevant to Corvairs.

I've been bringing a 1974 MG Midget back-to-life as time has permitted over the past year and a half. The car had about 4 gallons of 10 year old gas when I got it which I immediately drained. The gas was foul smelling and obviously totally stale.

Since that time, I've run the engine quite a bit and it normally runs very well, but twice now I've had a strange problem. After sitting for maybe a month, the car won't start or will run for a second and then die. The first time it occurred, I pumped all the new (month old) gas out and then it started up fine. Last weekend the problem recurred and when I pumped out some gas into a cup, I saw that the gas was very dark yellow.

The color of the gas leads me to believe that the fresh gas is getting contaminated by the old varnish in the tank. My primary question is:

What effect would dissolved varnish have on the combustibility of the new gas?

Has anyone had a similar experience with old gas residue making new gas go bad?

Thanks!

John
67 Coupe 110/4-spd

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Re: Tank Varnish Contaminating New Gas?
Date: March 19, 2017 04:11PM

It's not really varnish, as I'm sure you know, but it is the residue of the decade old gas after all the volatile components have drifted away.
It definitely needs to come out of there, It will continue to contaminate the gasoline you add to the tank.
Remove it, take it to a place that will get the insides clean!


Dan Davis ~ Pierce County, WA ~ CORSA Western Director + Corvairs NW + North Cascades Corvairs + Corvanatics
1966 Corsa Turbo coupe ~ ~ 1966 140 Corsa ~ ~ 1965 Monza 140/4 'Vert Sierra Tan/Fawn ~ 1964 Monza 'Vert (SOLD) ~ 1960 Monza Ermine White/Red PG ++ ~ 1965 Monza 140/4 Evening Orchid w/ ivory/black interior ~ 1962 Monza Wagon 102/4 ~ 1963 Rampside/Scamper ~ 1963 Red/Greenbrier ~ 1969 Ultra Van #468

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Re: Tank Varnish Contaminating New Gas?
Posted by: 66vairman ()
Date: March 19, 2017 05:09PM

Also check your fuel hoses. Even today you find cheapy fuel hose at FLAPS that will dissolve and turn the gasoline dark.

Buy Gates Barricade fuel hose. The lower pressure is fine for a manual fuel pump car. The higher pressure hose is for modern F.I. and costly, but also works fine.

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Re: Tank Varnish Contaminating New Gas?
Posted by: Timothy Shortle ()
Date: March 19, 2017 06:43PM

I would suggest remove the fuel tank and take it to a radiator shop for hot tank cleaning. And certainly use the higher pressure hose if you convert it to Browns EFI as the S U carbs are very unreliable and inefficient.

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Re: Tank Varnish Contaminating New Gas?
Posted by: Frank DuVal ()
Date: March 19, 2017 07:59PM

Quote
Tim
And certainly use the higher pressure hose if you convert it to Browns EFI as the S U carbs are very unreliable and inefficient.
thumbs upspinning smiley sticking its tongue out
smileys with beergrinning smileysmiling bouncing smileysmiling smiley

Excellent! (in Mr. Burn's voice)

Frank DuVal

Fredericksburg, VA

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Re: Tank Varnish Contaminating New Gas?
Posted by: Frank DuVal ()
Date: March 19, 2017 08:06PM

John,

If you take the tank out, you can see if it is much heavier than an empty tank should be. If heavier, all that extra crap has to come out or the new gasoline will continue to be a solvent and put it back in solution.

Frank DuVal

Fredericksburg, VA

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