Fuel related code

Tiny
NASER NASER
  • MEMBER
  • 2008 VOLKSWAGEN PASSAT
  • V6
  • 2WD
  • AUTOMATIC
  • 162,000 MILES
I have a rough cold idle and then gets somewhat better when warm but no driving related issues. I have this code and I included some readings. Can you see anything odd in any of the readings?
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Thursday, March 19th, 2020 AT 3:20 PM

36 Replies

Tiny
KASEKENNY1
  • EXPERT
Yeah. Your fuel pressure is low. Spec is 6 bar at key on which is 87 PSI. You are at 3 bar which is 43 PSI. This is assume you have the 3.6L engine. Do you have the turbo engine?

The fact that you have a code for the sensor, could just be a faulty reading but the fact that you have cold idle issues, points to a mechanical issue which low pressure would make sense.

Let me know what engine you have and we can go from there.
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Thursday, March 19th, 2020 AT 4:44 PM
Tiny
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Non turbo 3.6l. Cold issues are not major just rough running at idle but revving the motor gives a smooth strong motor.
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Thursday, March 19th, 2020 AT 6:42 PM
Tiny
KASEKENNY1
  • EXPERT
Yeah. Sounds like a weak fuel pressure issue. If you want to confirm it, hook up a mechanical gauge and see what it is while running. All that is doing is confirming the sensor is correct. However, I don't see any reason to doubt the sensor.

This means it could be a weak pump, restriction in the system. However, if it runs well it is not needed until it seems to get worse.
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Thursday, March 19th, 2020 AT 7:01 PM
Tiny
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So after I measure the pressure by a gauge and confirm that it is low, how would I go about eliminating whether it is a sensor or a weak pump?
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Thursday, March 19th, 2020 AT 7:18 PM
Tiny
KASEKENNY1
  • EXPERT
If a mechanical pump shows low pressure then the sensor is correct and its weak pump or other reason for low pressure. If the gauge is showing higher then the sensor is incorrect.
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Friday, March 20th, 2020 AT 7:17 AM
Tiny
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Where is the fuel gauge connector on this engine?
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Friday, March 20th, 2020 AT 1:49 PM
Tiny
KASEKENNY1
  • EXPERT
I copied it but never attached it. Sorry. Here is the process. It calls for special tools but it is not required.
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Friday, March 20th, 2020 AT 1:55 PM
Tiny
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So there is no traditional nipple? I got to remove the hose from the connector?
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Friday, March 20th, 2020 AT 2:29 PM
Tiny
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I have this kit would it work?
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Friday, March 20th, 2020 AT 2:32 PM
Tiny
KASEKENNY1
  • EXPERT
The gauge is fine. The only thing I don't know if the adapter for the engine. That kit should come with an application chart for each fitting. If it doesn't, do they include a call center? I have numerous tools that I have called and they are able to tell me which fittings apply to each vehicle.

I tried to cross reference the adapter number from the procedure but it doesn't pull anything. I would see if one fits on and if not, just see if you can call the company for an application chart.
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Friday, March 20th, 2020 AT 2:54 PM
Tiny
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But there is no fitting on the car, hoses only.
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Friday, March 20th, 2020 AT 2:57 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Just wanted to jump in. If there is no schrader valve, then you have to use a T at one point in the system. Basically, you are making a schrader valve to test the pressure. As he mentioned, the kit should indicate that type of set up. Most times a T is added at the fuel rail between the rail and the supply line.

It's just a thought.

Joe
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Friday, March 20th, 2020 AT 3:13 PM
Tiny
KASEKENNY1
  • EXPERT
You are correct. Sorry, I didn't look at the process that closely. At that point all you need to do is splice this gauge in the supply line. This kit may not have what you need to do this but I am sure any parts store will have a selection of fuel line fittings that you can make it using the fittings and then just rubber fuel line.

Does this make sense? If not I can try to make a diagram/drawing of what the set up will look like.
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Friday, March 20th, 2020 AT 3:15 PM
Tiny
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I may not be very familiar with all of that. Is this the only way to get a reading? Stupid VW, who doesn't provide a valve for fuel testing?
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Friday, March 20th, 2020 AT 3:17 PM
Tiny
NASER NASER
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Ya, if you can show me how to get it done and which of the hoses is the supply line. I assume the one that goes to the front of the motor where there is a sensor attached in the middle of it?
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Friday, March 20th, 2020 AT 3:23 PM
Tiny
KASEKENNY1
  • EXPERT
They are proud of their engineering ability and it shows here because a schrader valve is too easy.

You would need to find fittings that fit on the line and engine port. Take a look at the drawing. This is clearly just a rough idea of what it needs to do. The fuel pressure just needs to go through the gauge anyway it can.

Unfortunately there is no other way of confirming the sensor is accurate. The only option I think we have to to replace the sensor and see if it is any different. If it is then clearly that was the issue. If not then we have weak pressure. Clearly not desirable.
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Friday, March 20th, 2020 AT 3:44 PM
Tiny
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I will take a chance on the sensor and then see since it's cheap. Thanks. Will keep you updated. Is it called fuel pressure sensor?
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Friday, March 20th, 2020 AT 3:47 PM
Tiny
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I see one that looks like it, but online it says that some of them are on top of the fuel pump. And some on the HPFP.
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Friday, March 20th, 2020 AT 3:52 PM
Tiny
KASEKENNY1
  • EXPERT
Yes It is. I just checked to see if there was a test for the sensor itself and surprisingly enough there was. This may not be easier then just replacing it but may be worth a try.
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Friday, March 20th, 2020 AT 3:53 PM
Tiny
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On right side of picture.
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Friday, March 20th, 2020 AT 3:55 PM

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