Fuel pressure values of stock Hitachi HPFP

[mc_hotmail]

Warm starting my '07 A4 now needs to crank a bit longer than before, or it will fail to idle once the key is let go. Once idle, no issue at all. Never fail a cold start either (weird). I helped my brother replaced his '06 A4 HPFP to get it running again, so I suspect may be my issue is a sign of weakening pump.

Has anyone hook up a fuel pressure gauge to that blocked out port with a plastic plug? and if yes, what is the normal reading?

The silver open port in this photo:
https://c1552172.ssl.cf0.rackcdn.com/732623_x800.webp

[Darepoole]

The photo is broken on my end but could just be me


Sent from my iPhone using Tapatalk

[mc_hotmail]

The image is a newer format that works in Chrome and FireFox, fails in Safari. It's the 4th photo in this ECS page:

High Pressure Fuel Pump (https://www.ecstuning.com/b-hitachi-parts/high-pressure-fuel-pump/06f127025k~hit/)

[esandes]

Check the battery, try $3 autolite copper plugs. I doubt there's a problem with the pump.

[Jayz691]

Best way to check pressure is with vcds(or Obdeleven pro). Look at live data on blocks 230 and 231. Can see what low pressure ya got after priming, and what rail pressure is at startup.

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[Charles.waite]

Pull codes and log fuel pressure before you parts darts this.

[mc_hotmail]

VCDS shows (103-1 Current Fuel Pressure, 106-1 Fuel Rail):

Power on:
Current Fuel Pressure: 6.8 bar
Fuel Rail: 7 bar

Idle:
Current Fuel Pressure: 4.9 bar
Fuel rail: 53.8 bar

Driving (not able to save the graph):
Fuel rail: goes up and down

No code.

[Charles.waite]

Seems normal to me. How much does it fluctuate though? Full throttle should be around 110-120 bar. Idle is 50-60 I believe.

Edit: Actually, wait should the low side drop that much at idle? Maybe someone else might know if that

[esandes]

That pressure at idle is normal.

But who gives a shit let's play parts darts! When you have a wad of cash burning a hole in the pocket buy some parts and say a hail Mary.

[EvolutionArmory]

Check the battery, try $3 autolite copper plugs. I doubt there's a problem with the pump.

And you came to that conclusion how exactly? 🤣🤣

You never change, do you?

[EvolutionArmory]

Now that you have high pressure readings, take the car for a nice drive, like 20 minutes, pull over and check low pump duty cycle at idle. It should be around 50% for a healthy low pump. If it’s higher than 55%, maybe you need a new low pump.

[EvolutionArmory]

Seems normal to me. How much does it fluctuate though? Full throttle should be around 110-120 bar. Idle is 50-60 I believe.

Edit: Actually, wait should the low side drop that much at idle? Maybe someone else might know if that

Low side pressure at idle should be between 5-6 bar. It should give you the limit of what the regulator in the fuel filter will allow you to get.

[Jayz691]

Low pressure-4.5bar stock map
Rail pressure-50bar
Both at idle.
Max rail pressure on stock map is 109.9bar, on stock map.

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[mc_hotmail]

Thank you. By "stock map", are you referring to some VCDS database?

[Jayz691]

Thank you. By "stock map", are you referring to some VCDS database?No, just meaning stock values. When tuned, tuner will/may change some requested values. Usually only the max rail pressure, but just wanted to mention those were stock values.

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[arankaspar1]

Can someone measure ohm resistance on the fuel pressure regulator? And Include the part number you have?