Hi all.
We have a 1998 audi A4 1.9tdi PD AWX which has a major fuel pressure problem on the low pressure side.
Customer driving and experiencing no problem when cut out and would not restart.
Breakdown company call and recovered to garage.
I noticed that fuel filter had a slight mis-shaped look about it, not giving it much though i removed the fuel line to filter to check for fuel and to rule out low pressure pump, as i removed line, a massive release of pressure and diesel everywhere!
using vcds there was no error codes logged.
on cranking with lines removed we had a nice flow of fuel from tank, but could hear a dominate rattle from tandem pump, removed pump and found drive gear had sheer.
new pump and filter fitted, turned key and ran fine.
left ticking over for around 10 mins then cut out.
looking again and fuel filter mis-shapen! fuel line removed and way to much pressure again!
its the fuel filter with inlet and pump supply on top and plastic valve that allows fuel to return from to tank. If i remove the return line on return side we having nothing going back to tank, but fuel on return going to valve, but its had 2 new mahl filters and i cant see there being two fault valves. if i blow sharply down valve it clicks and wont allow anything to flow through, if i blow gently it allows free movement, leading me to think i have to much pressure on the return fuel line from engine and closing valve and restricting flow. but i cant work out why we would have so much pressure on the return side?
sorry for long post, anyone experienced this fault before?
kind regards
Dave
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