ethanol
Joined: Nov 2001
Posts: 34,610
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From: Schiller Park, ILL Member: #317
Increasingly stringent evaporative emission regulations have caused GM to introduce returnless fuel systems. In a returnless design, no fuel is sent back to the fuel tank from the engine. All fuel leaving the tank flows through the fuel injectors.
Returnless systems have been in production since 1998 (Trans Am, Camaro and Corvette). A significant migration toward returnless fuel systems began in the 2004 model year. By 2007, the majority of GM vehicles will be converted to the returnless design.
Any contamination (including rust) that is built into or forms in the fuel line will find its way to the fuel injectors. A filter at the inlet to the fuel injector filters out small contaminants, including rust (fig. 11). If enough debris accumulates on the injector filter, it will start to restrict flow. This will have a negative effect on performance and driveabilty.
For the 2004 model year, there has been an increase in the number of injectors returned with rust in the injector filter. The rust appears to be coming from several sources:
- the chassis fuel line
- the crossover pipe on the Gen III fuel rail.
Both pipes are made of low-carbon steel, and the inside of the pipe is not coated. If water gets into the fuel system, it has the potential to rust the line.
When diagnosing driveability symptoms due to clogged fuel injectors, follow the procedures outlined in bulletin 03-06-04-030A. If the bulletin procedures lead to replacing an injector, inspect the removed injector for evidence of rust contamination. If rust is plugging the fuel injector, replace it, because a procedure for removing rust from the injector filter has not been developed.
If rust remains in the fuel line, there is a chance that the injector filter will plug up again. Whenever rust is observed in an injector, flush the fuel lines. If the fuel line cannot be completely flushed of rust, replace it.
A small amount of rust in the fuel tank will typically not cause a problem. The fuel filter will prevent the rust from getting to the injectors. The capacity of the filter is large enough to keep it from plugging up. There is also a strainer (“sock”) at the inlet to the fuel pump. The strainer prevents contamination from getting into the fuel pump and causing problems. However, rust in the fuel tank is a sign that water may be in the tank. If rust is observed in the fuel tank, empty it and flush with hot water, according to SI procedures.
Returnless systems have been in production since 1998 (Trans Am, Camaro and Corvette). A significant migration toward returnless fuel systems began in the 2004 model year. By 2007, the majority of GM vehicles will be converted to the returnless design.
Any contamination (including rust) that is built into or forms in the fuel line will find its way to the fuel injectors. A filter at the inlet to the fuel injector filters out small contaminants, including rust (fig. 11). If enough debris accumulates on the injector filter, it will start to restrict flow. This will have a negative effect on performance and driveabilty.
For the 2004 model year, there has been an increase in the number of injectors returned with rust in the injector filter. The rust appears to be coming from several sources:
- the chassis fuel line
- the crossover pipe on the Gen III fuel rail.
Both pipes are made of low-carbon steel, and the inside of the pipe is not coated. If water gets into the fuel system, it has the potential to rust the line.
When diagnosing driveability symptoms due to clogged fuel injectors, follow the procedures outlined in bulletin 03-06-04-030A. If the bulletin procedures lead to replacing an injector, inspect the removed injector for evidence of rust contamination. If rust is plugging the fuel injector, replace it, because a procedure for removing rust from the injector filter has not been developed.
If rust remains in the fuel line, there is a chance that the injector filter will plug up again. Whenever rust is observed in an injector, flush the fuel lines. If the fuel line cannot be completely flushed of rust, replace it.
A small amount of rust in the fuel tank will typically not cause a problem. The fuel filter will prevent the rust from getting to the injectors. The capacity of the filter is large enough to keep it from plugging up. There is also a strainer (“sock”) at the inlet to the fuel pump. The strainer prevents contamination from getting into the fuel pump and causing problems. However, rust in the fuel tank is a sign that water may be in the tank. If rust is observed in the fuel tank, empty it and flush with hot water, according to SI procedures.
Where does it say anything specific about ethanol causing it though? Did I miss something?
Joined: Nov 2001
Posts: 34,610
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From: Schiller Park, ILL Member: #317
Originally Posted by 99PontTA
i'm not trying to argue either..i have the parts and gm's admission to prove it.I think the problem gets bad when you mix ethanol-water and don;t drive the car everyday.Dealer tech warned me these cars trap water in the rail..it can't get through the injectors easily and its has no place to go so it gradually buids up in the rail and lines.Of course after a few months of this lots of damage can accur.Our 99ta was only driven 10k a year... and sat during the winters.One more thing is the O2 carrying ethanol mixed with water gets corrosive fast.
The car has always had the local dose of ethanol.
Banned
Joined: Nov 2003
Posts: 246
Likes: 0
From: Pocono Pa
there has been an increase in the number of injectors returned with rust in the injector filter. The rust appears to be coming from several sources:
- the chassis fuel line
- the crossover pipe on the Gen III fuel rail.
Both pipes are made of low-carbon steel, and the inside of the pipe is not coated. If water gets into the fuel system, it has the potential to rust the line.
Now mix water and ethanol and oput it these fuel system...its a kNOWN FACT ethanol contains LOTS OF WATER...so does gasoline.
- the chassis fuel line
- the crossover pipe on the Gen III fuel rail.
Both pipes are made of low-carbon steel, and the inside of the pipe is not coated. If water gets into the fuel system, it has the potential to rust the line.
Now mix water and ethanol and oput it these fuel system...its a kNOWN FACT ethanol contains LOTS OF WATER...so does gasoline.
Joined: Nov 2001
Posts: 34,610
Likes: 2,522
From: Schiller Park, ILL Member: #317
Originally Posted by 99PontTA
i hope yer not serious...i';m guessing you are being an AZZ
Teching In
Joined: Jan 2005
Posts: 34
Likes: 0
Originally Posted by 99PontTA
by the way there is a HUGE flaw in returnless fuel systems...they tend to trap water in the fuel rail...you can only guess the outcome of mixing water with ethanol in a carbon steel environment......
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Verdad Gallardo Joined: Nov 2001
Posts: 34,610
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From: Schiller Park, ILL Member: #317
Originally Posted by 99PontTA
I think the problem gets bad when you mix ethanol-water and don;t drive the car everyday......Our 99ta was only driven 10k a year... and sat during the winters.
What I could see of the fuel line internals looked fine where they meet the filter.
Inside of the filter showed no signs of rust.
No external signs of fuel line deterioration.
No injector or fueling issues.
Plugs look good.
good luck!yer gonna need it.
Joined: Nov 2001
Posts: 34,610
Likes: 2,522
From: Schiller Park, ILL Member: #317
Originally Posted by MSURacing
If anyone has more questions, please ask them on here because I think there are many questions about ethanol and it should all be public knowledge. That is what this website is for, to gain knowledge.
What's your take on using E10 in an LS1 fuel system, on a long term basis, in a car that sits for extended intervals? In your experiance, is that alone reason enough to cause major corrosion issues in an returnless fuel system?
