High pressure fuel pump testing

[ttthomas94]

I'm just wondering what the best way to test a high pressure fuel pump as I'm thinking it could be causing issues. The only way I can think of is by removing an injector and turning it over so see if fuel is getting there.

Also what are the most common failures. Am I right in saying the pump relies on the fuel pressure sensor on the rail to work? So could that be the fault? Any more info from someone with more experience would be appreciated.

Car is a 3.0tdi a4 b7

 

[EXSpartan36]

You can Log the fuel pump pressure with VCDS not sure what blocks to measure. I wouldn't advise taking an injector out and trying it. If the system is working correctly most Common rail engines work at around 300 bar.

 

[ttthomas94]

You can Log the fuel pump pressure with VCDS not sure what blocks to measure. I wouldn't advise taking an injector out and trying it. If the system is working correctly most Common rail engines work at around 300 bar.

Tried logging with vcds and reads 0bar while cranking making me think it could be the sensor. No fault codes that would be stopping it starting.


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[Sturat]

I bought a 3.0 tdi as a 'non starter' the rails had been disconnected (I presume to see there was fuel pressure and whether one of the fuel pumps was not doing its job). Turned out to be crank sensor problem very easy and cheap to replace as its situated at the back of the engine close the battery.

 

[ttthomas94]

I bought a 3.0 tdi as a 'non starter' the rails had been disconnected (I presume to see there was fuel pressure and whether one of the fuel pumps was not doing its job). Turned out to be crank sensor problem very easy and cheap to replace as its situated at the back of the engine close the battery.

From my understanding the fuel pump is controlled by the ecu as to when it pumps more or less after it receives information from the fuel pressure sensor and the crank sensor. So if either sensor failed it would likely stop it pumping. The worry is that no fault code has come up. I've unplugged the pressure sensor and tried and it throws a code suggesting there's nothing wrong with that. Also unplugged the pump solenoid with the same result. Haven't done the crank sensor but might be worth it. Is it easy to access?


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[Sturat]

The faulty crank sensor didn't throw up any fault readings on mine.
You may be right about it controlling the pump? I thought it just stopped the injectors from working as they need be activated in relation to the position of the crank ?
Replacing the crank sensor is very very easy anyway and extremely easy to get to on a 3.0 tdi v6.
I'll take a photo of the position if you like?

 

[ttthomas94]

The faulty crank sensor didn't throw up any fault readings on mine.
You may be right about it controlling the pump? I thought it just stopped the injectors from working as they need be activated in relation to the position of the crank ?
Replacing the crank sensor is very very easy anyway and extremely easy to get to on a 3.0 tdi v6.
I'll take a photo of the position if you like?

I'll look it up and report back. Thanks for you're help.


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[ttthomas94]

The faulty crank sensor didn't throw up any fault readings on mine.
You may be right about it controlling the pump? I thought it just stopped the injectors from working as they need be activated in relation to the position of the crank ?
Replacing the crank sensor is very very easy anyway and extremely easy to get to on a 3.0 tdi v6.
I'll take a photo of the position if you like?

Right had a quick google and finding mixed opinions. You say it's easy and near the battery. Other people are saying it's a pain in the **** and it's on the bell housing.


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[Sturat]

I'll take a pic tomorrow for you

 

[ttthomas94]

Got the problem sorted. I was looking in the totally wrong place. When I wires my head unit I had to move the pins to get the 12v and switched 12v in the right place. Somehow this told the car the hu had been stolen which for some stupid reason shuts down the whole car. Just glad it wasn't an expensive fix.


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