MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: soulaus on January 24, 2023, 08:49:44 am

Title: .7 bar fuel pressure
Post by: soulaus on January 24, 2023, 08:49:44 am
Hi all,

2009 Mk5 GTI, Australia, done around 220k.

Firstly, a bus overtook me at the traffic lights.  Yes, a bus.  I'm not used to that.  I want my car back.  The one with power.

So this all started about 6 months ago - got back from holidays and the car would turn over but never stay started.
Called a mobile mechanic, he came out and replaced the high pressure fuel pump at the engine end.  Alll good..
2 Weeks or so later car just didn't have any power, I could get it up to about 1.5/2k RPM before I got no extra power from the engine at all..
Took it to my 'normal' mechanic, she replaced the fuel filter just under the drivers seat(ish), found no problems with fuel but she didn't have time to get it seen to.
Found another local mechanic after a few months and he firstly had to push the car in as it wouldn't start, but after replacing the rear fuel pump (he said it looked like it was from a bygone era) he got it to start every few goes then he'd go around the block in it and it'd start misbehaving again.
He plugged in a doozit (official term) and the doozit is saying there's only point 7 (.7) bars of pressure in the fuel line when there should be around 14 bars.

He's now replacing the sensor in case that's to blame but was wondering if anyone else has any suggestions ? 

Think of my mechanic, there's a slab of beer riding on him getting it fixed for me and I'll be drunk if I don't help him to solve this one.

Thanks,
SoulAus
Title: Re: .7 bar fuel pressure
Post by: mjmallia on January 24, 2023, 10:42:41 am
Could be a worn out cam lobe from previous poor maintenance of the HPFP follower being worn........or the LPFP is dying and not providing enough flow to the HPFP
Title: Re: .7 bar fuel pressure
Post by: pudding on January 24, 2023, 01:38:49 pm
Both pumps and the filter have been changed according to the OP.

HPFP should be 50bar at idle.
LPFP range is 4.5 - 6.5 bar from idle to full load, but usually hangs around 5 bar at idle, from memory.

0.7 is basically nothing. Someone has stolen all your bars.

Uncleben on here, yes he who makes the packet rice, is having the same problem. Engine falls on it's face past 2K, and very low pressures on the diagnostics.  It must therefore be some kind of fuel related Covid 19 affecting GTIs, and it's spread to Australia.

I'll assume the return and supply lines weren't switched on the filter during replacement  :smiley: