MK5 Golf GTI
All Things Mk5 => Mk5 General Area => Topic started by: dennis10 on August 07, 2025, 10:07:58 am
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Just still tracking down my stumbling first cold start of the day in my ED30
The low pressure fuel pump, how much noise should it make when you open the door and/or prime with the key? I think I can hear something very faint, but it's almost nothing - should it be pretty noticeable in the mk5?
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Checked or replaced the HPFP cam follower recently?
Fuel filter change every two years?
You should hear the a faint pump noise for a couple of seconds then stop when the drivers door is used.
It will also prime on the key just prior to holding for ignition.
Have you tried double priming to see if that improves the cold start. I noticed it helped on mine and discovered I had a leaking bleed back valve on the pump due to its age and miles. I got a genuine second hand one as a new genuine pump was £270 + VAT
The latest part number is 1K0919051DB and got one off a 1.4TSI Scirroco 2018 with low miles and 14 years younger for peanuts (£31) to give it a go. I also discovered I had a pinched pump to tank seal from factory like a few other people
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Thread here
https://www.mk5golfgti.co.uk/forum/index.php/topic,134529.msg1164972.html#msg1164972
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Checked or replaced the HPFP cam follower recently?
Fuel filter change every two years?
You should hear the a faint pump noise for a couple of seconds then stop when the drivers door is used.
It will also prime on the key just prior to holding for ignition.
Have you tried double priming to see if that improves the cold start. I noticed it helped on mine and discovered I had a leaking bleed back valve on the pump due to its age and miles. I got a genuine second hand one as a new genuine pump was £270 + VAT
The latest part number is 1K0919051DB and got one off a 1.4TSI Scirroco 2018 with low miles and 14 years younger for peanuts (£31) to give it a go. I also discovered I had a pinched pump to tank seal from factory like a few other people
Yep new cam follower, old one was fine, cam is fine. New fuel filter too
I have a Citroen Berlingo 1.6 16v petrol that is very noticeable when it primes, both ignition and opening the door, but I don't have that in the GTI, but I don't have one to compare to so wasn't sure if the GTI was just quiet. I can hear a very faint something, but nothing like in the Citroen.
Yes double priming helps - it doesn't always completely cure it, but it's much better after priming it beforehand than not.
I'll look towards the LPFP then - how did you find out yours had a faulty return valve - did you test with a multimeter?
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Just bought a used LP fuel pump from a 2013 VW Beetle 1.2 with the part number 1K0919051DB for just £20 - hopefully will fix the cold start for not much money!
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Just still tracking down my stumbling first cold start of the day in my ED30
The low pressure fuel pump, how much noise should it make when you open the door and/or prime with the key? I think I can hear something very faint, but it's almost nothing - should it be pretty noticeable in the mk5?
Any updates?
Gonna slide in with my 2 cents on the matter. So something funny I noticed over the past 2 years since I've had this issue, after every oil top-up or oilchange, the engine starts up right away for some time. The longer I go with the same oil, the worse my starts get. When the engine used up 1 liter and I filled it up with a fresh liter, my starts went back to normal.
I'm fairly certain I have piston ring issues cause the oil smells heavily of fuel. Way way more than my 1.4 which doesnt use any oil at all. Fuel thins out the oil which drops oil pressure significantly. Pair this up with an old engine that is notorious for oil pressure problems and I can see why the VVT would be misaligned/take some time to align, which explains the cold starts in a way.
These engines also have squirters under the pistons which are supposed to be closed and only open after a certain oil pressure/temperature. But overtime, they get stuck open permanently.
Then again, I could be entirely off. It's just speculation at this point.
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Just still tracking down my stumbling first cold start of the day in my ED30
The low pressure fuel pump, how much noise should it make when you open the door and/or prime with the key? I think I can hear something very faint, but it's almost nothing - should it be pretty noticeable in the mk5?
Any updates?
Gonna slide in with my 2 cents on the matter. So something funny I noticed over the past 2 years since I've had this issue, after every oil top-up or oilchange, the engine starts up right away for some time. The longer I go with the same oil, the worse my starts get. When the engine used up 1 liter and I filled it up with a fresh liter, my starts went back to normal.
I'm fairly certain I have piston ring issues cause the oil smells heavily of fuel. Way way more than my 1.4 which doesnt use any oil at all. Fuel thins out the oil which drops oil pressure significantly. Pair this up with an old engine that is notorious for oil pressure problems and I can see why the VVT would be misaligned/take some time to align, which explains the cold starts in a way.
These engines also have squirters under the pistons which are supposed to be closed and only open after a certain oil pressure/temperature. But overtime, they get stuck open permanently.
Then again, I could be entirely off. It's just speculation at this point.
Well the second hand LPFP I sourced for £20 turned out to have a broken fuel return pipe, which must've happened during packing as the photos showed it intact - got a refund for it, so I'll just keep the unit as a spare. I've now ordered a brand new Meyle unit for £70 and am waiting for it to arrive.
My engine is a BYD ED30 engine, doesn't use any oil between oil changes - can't say I've noticed any difference when doing the yearly/5k mile oil change, no smell of fuel in the oil either, but interesting to consider.
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Fitted the new Meyle low pressure fuel pump to my Edition 30. Have only had 1 cold start since installing it as I've been away, but unfortunately it still spluttered into life (without priming it, to test new fuel pump)
Where there is a massive difference is the drive of the car since replacing the fuel pump - MPG is way up, I was struggling to get 29/30mpg despite driving sensibly for long periods and it had been like that for quite some time, I just put it down to being an older car, less economical etc etc. It turns out this is not the case, and on the 2 drives I've had since replacing, I easily obtained around 34/35mpg for the whole journey, despite spirited driving and when trying to drive it frugally, obtained 39mpg! On top of this, the car feels MUCH more urgent and nippy at lower rpms, needing less throttle input to get it going, so maybe wasn't getting the fueling it needed.
Worth checking your low pressure fuel pump if you have bad MPG. I'll do a couple more cold starts before admitting that I still have that issue, but at least it has been positive in other areas.