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WR/KG Fuel Injection - Adjusting System Pressure

Parts required:

• 035 198 685 Parts kit for metering head
• N 013 807 6 (x2) Crush washers

Tools required:

• Fuel Pressure Gauge

Procedure:

• Check SAFETY. Spilt fuel is a fire that has not yet ignited; spilt fuel vapour is an explosion that has not yet happened; a car with a fuel leak is a bomb that has not yet gone off
• Check that the banjo bolt on the feed to the metering head has a flat, unengraved surface. If it has a circle engraved in it, replace it with a non-constrictor bolt.
• Pack the space behind the metering head with rags.
• Attach the fuel pressure gauge and set it to read system rather than control pressure
• Remove the fuel pump relay and insert a switched jumper (sealed switch - no sparks, e.g., VAG 1348/3-1) from the battery to the large terminal nearest the side of the fuse box
• Check the replacement regulator spindle delivered in the kit of parts, and identify the old one on the back of the metering head
• Loosen the old regulator to finger tight
• Pulse the fuel pump via the switch in jumper lead
• Whip the regulator out smartish. The idea is to use the fuel spurt to clean the piston's seat. The piston is small and very easily damaged - DO NOT LET IT FALL ON THE FLOOR - if it doesn't come all the way out, fetch it with a magnetic retriever
• If working in a VERY well ventilated environment, clear the rags out and pulse the fuel pump again - 1/2 second maximum
• Look at what you have in your hand and the parts Audi shipped. Note that the sealing O-ring on the very end of the plunger comes in two forms - circular and shield-shaped cross-section. Fit the one from the packet that matches the one on the plunger you took out - probably the shield-shaped one
• Put it all back and run the fuel pump to measure the system pressure
• System pressure should be about 5.85 bar. There's no performance advantage in any more. The shims in the packet are worth about 0.2 bar each - some are slightly thinner than others. Pull the plunger back out and add/subtract shims until you get 5.8 bar or something very close.
• Remove the fuel pressure gauge and fit new crush washers
• Remove the rags if still in place
• Run the fuel pump for at least one minute and check for leaks

Cleanliness is EVERYTHING. Lint-free cloths (used to be able to get them in photographic shops like Jessops) are magic. Kitchen roll will do at a pinch. The piston MUST be clean.

This procedure is illegal in many countries unless you hold a recognised mechanic's qualification. I recommend pulling the rags out and letting all the fuel evaporate, then running the pump for a minute to check for leaks. Remember - the downpipe and turbo get very hot and are not far away.

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