FSI Fuel Hoses?

Jellybean

Jellybean

A2OC Donor
Guys the flexible fuel hoses on my FSI are cracking and some leaking. When replacing do you buy the correct moulded hoses or just use Petrol Hose, and cut to length? It strikes me that none of the moulded hoses seem to be complicated hence my question.
I guess the cracking is old age, bit I wonder if the leaks are due to biofuel additives in fuel? These hoses were never intended for use with biofuel.
Any constructive suggestions appreciated.

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Last edited:
Jellybean said:
Generally no, but FSI should be run on premium fuel.

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Premium Unleaded, on UK forecourts is E10, 95 octane, and contains up to 10% alcohol, and should never be used in an FSI.
The FSI engine is not compatible with E10, due to components, (such as fuel lines), not being resistant to the high alcohol content.
Only Super Unleaded, E5, (with a maximum of 5% alcohol, but typically little or none), should be used in an FSI.
Mac
 
Was that ever confirmed Mac? I know that when E10 was coming in the A2 FSI was on the list of Audi cars not compatible but I do think it was ever established why?

It could just be in the same sense that an A2 FSI shouldn’t be run on the old 95Ron (unless it’s got a ProBoost ECU).
 
FSIs could be run on premium unleaded, 95 octane, albeit with reduced performance, until the amount of alcohol in premium unleaded was increased to 10%, with the introduction of E10, in September 2021
If you Google Audi E10 compatibility, you'll find this text from Audi, it's on several Audi dealer web sites, this is copied from the Audi Poole website. Pretty unambiguous.
Mac.

E10 petrol is cleared for use in all Audi petrol-fuelled vehicles, excluding the following vehicles:
First-generation direct-injection engines:
  • Audi A2 1.6 FSI, model years 2003-2005
  • Audi A3 1.6 FSI, model year 2004
  • Audi A3 2.0 FSI, model year 2004
  • Audi A4 2.0 FSI, model years 2003-2004
  • Audi A4 Saloon petrol engine models with original equipment manufacturer (OEM) parking heater, of model years 2001-2008
  • Audi A4 Avant petrol engine models with OEM parking heater of model years 2002-2008
Note: vehicles listed above should continue to use E5 petrol (standard unleaded).

What happens if E10 petrol is put into an incompatible car?

E10 fuel will not cause immediate damage to the car but prolonged use could cause long-term problems.
Increasing the ethanol level in petrol poses two main risks to older cars. The first is that as a solvent, it can cause degradation of rubber and plastic components, such as hoses, seals, fuel lines and filters. It also absorbs water from the atmosphere, potentially leading to condensation and corrosion in fuel tanks, lines and other metal components.
 

Fuel line; fuel filter Audi A2 (A2) 2003 year Audi EUROPA 201043

fuel line<br/>fuel filter Audi A2 (A2) 2003 year Audi EUROPA 201043 spare parts
audi.7zap.com audi.7zap.com

A roll of the hose of the correct grade appears to be p/n N10303504, although I assume that any good quality fuel-grade hose would work if hose in your car is showing signs of aging. Searching the above number elicits a lot of links to coils of hose from Febi Bilstein among others at very competitive prices so should be easy to get something suitable.

As to whether it is down to additives in the fuel - as noted above, E10 grade fuel is actively dissuaded by Audi in the 1.6FSi engine - but my initial guess would be that the bulk of pipe degradation now is due to passage of time. E10 won't help, but it won't melt it straight away.
 
Robin_Cox said:

Fuel line; fuel filter Audi A2 (A2) 2003 year Audi EUROPA 201043

fuel line<br/>fuel filter Audi A2 (A2) 2003 year Audi EUROPA 201043 spare parts
audi.7zap.com audi.7zap.com

A roll of the hose of the correct grade appears to be p/n N10303504, although I assume that any good quality fuel-grade hose would work if hose in your car is showing signs of aging. Searching the above number elicits a lot of links to coils of hose from Febi Bilstein among others at very competitive prices so should be easy to get something suitable.

As to whether it is down to additives in the fuel - as noted above, E10 grade fuel is actively dissuaded by Audi in the 1.6FSi engine - but my initial guess would be that the bulk of pipe degradation now is due to passage of time. E10 won't help, but it won't melt it straight away.
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Many thanks, just the answer I was hoping for.

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The information about fuels follow on from your comment:
"FSI should be run on premium fuel"
The constructive posts that followed explain why that is incorrect, and why, if you have been running on E10, that may have contributed to your hose failure.
Mac.
 
PlasticMac said:
The information about fuels follow on from your comment:
"FSI should be run on premium fuel"
The constructive posts that followed explain why that is incorrect, and why, if you have been running on E10, that may have contributed to your hose failure.
Mac.
Click to expand...
And I also agree with the points raised by Graham and yourself - the correct fuel is rule #1 for an FSi and probably the easiest to implement for any FSi owner.
 
Guys, my current FSI is the 5th I have owned. I know that it should run on premium fuel, unless a Pro Boost ECU is fitted.
My question was simply to ask if lengths of cut hose could replace the moulded hoses. I am advised elsewhere this is possible.

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Last edited by a moderator:
Jellybean said:
Guys, my current FSI is the 5th I have owned. I know that it should run on premium fuel, unless a Pro Boost ECU is fitted. I was not asking for googlers to give me chapter n verse about it.
My question was simply to ask if lengths of cut hose could replace the moulded hoses. I am advised elsewhere this is possible.

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You are mistaken when you say
"I know that it should run on premium fuel, unless a Pro Boost ECU is fitted"
This is not correct. Once 10% alcohol was added to the standard blend of petrol in UK, and designated E10, the only fuel that is compatible with the FSI is E5 Super Unleaded. This is nothing to do with the ECU, or octane rating, it's a basic incompatibility between 10% alcohol and the construction of the FSI engine and exhaust system.
The ProBoost map does adjust the engine tune to allow it to run on lower octane fuel, but it does not overcome the alcohol incompatibility.
Mac.
 
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