Tandem pump, checking fuel pressure using vcds...

glitdi

Veteran Member
Joined
Dec 28, 2009
Location
West Coast Canada
TDI
Tdi asv motor in a mk3 golf, om642 in a wk jeep
Any ideas how to check to see the tandem pump is working corectly using vcds?
Sorry for the newb question I am still trying to figure out the ins and outs of the vcds system.
I am assuming logs would be the best bet however I don't know which channels/controllers to plot.
Any suggestions would be greatly appreciated.
 

Ol'Rattler

Top Post Dawg
Joined
Jul 3, 2007
Location
PNA
TDI
2006 BRM Jetta
Like Dan said. VCDS can only report on something that has a sensor.

To check the Tandem pump pressure you need to connect a gauge with a "T" fitting in the output so that you can observe the operating pressure of the Tandem pump with the engine running.

Dead ending the Tandem pumps output with a gauge and cranking/running the engine will not give you an accurate operating pressure and will probably damage the Tandem pump.
 

Ol'Rattler

Top Post Dawg
Joined
Jul 3, 2007
Location
PNA
TDI
2006 BRM Jetta
Yea Dan, that some good info. That's exactly what the OP needs.

Kinda funny that folks sometimes think that VCDS will magically tell them what is wrong with their cars.:D
 

BeartheBruce

Vendor
Joined
Dec 22, 2005
Location
Southeastern PA
Kinda funny that folks sometimes think that VCDS will magically tell them what is wrong with their cars.:D
Happens way more often than you might think. We even get sales calls asking if it will fix their car..... people who think VCDS is a professional tech in a box. Well, we're good, but we ain't that good. ;)
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Happens way more often than you might think. We even get sales calls asking if it will fix their car..... people who think VCDS is a professional tech in a box. Well, we're good, but we ain't that good. ;)
Yes, that is always a funny conversation with the customer.

Them: [over the phone]: This light on my Jetta TDI is on, can you tell me what is wrong with my car?

Me: no, we will have to plug our computer into your car, and see why the light is on, then find out what is wrong with the car.

Them: yeah, but that computer tells you what is wrong.

Me: no, it tells me why the light is on.

Them: oh, so you just need to turn the light off? I can do that.

Me: no, the light is on because there is a problem, the computer allows me to see why the light is on, to afford me a starting point in diagnosis of the problem.

Them: but the car runs fine!

Me: yes, I'm sure it does, but the light can come on for many reasons and the computer in your car that makes the engine run is smart enough to be able to motor on even with a fault.

Them: well of it is smart enough to motor on, then why does it not just turn the light off by itself?

Me: because the car cannot fix itself, it can only alert you that it is having a problem.

Them: but it runs fine!

Me: [facepalm]: yes, but it may not continue to run that way, or it may have a fault that will cause poor emissions, poor fuel economy, poor power, or more.

Them: well it does seem to be slower now.

Me: oh, so your definition of "fine" is used on a sliding scale?

Them: well, it starts and moves. And hey, if my car already has a computer, why do you need yours to connect to it?

Me: well, actually your car has several computers, but none of them can print out what ails them, and some cannot even alert you via a light.

Them: you mean there are more lights?

Me: yes, many.

Them: where are those?

Me: [facepalm... again...]: all those red and orange lights that come on when you turn the key on.

Them: oh. Well, I also have this vibration. Can your computer tell you what that is?

Me: most likely not, I really need to see your car.

Them: for what, the light or the vibration?

Me: both.

Them: so how much will it cost to fix?

Me: I have no idea, because I have no idea what is wrong with your car.

Them: well I told you, I have a light on!

Me: [losing patience]: yes, but I need to have your car here, in the shop, for me to diagnose that!

Them: well, my sister-in-law said it is probably just a loose gas cap.

Me: [facepalm]: sounds like you have it licked then! Good luck! [click] :mad:
 

jetta 97

Vendor
Joined
Dec 25, 2008
Location
Dallas (McKinney) ,TX ,USA
TDI
2 X Jatta MK5 2006
Oh, common story that happens time to time.
I have same situations over and over.
One of the usual is:
"Why you have to charge me diagnostic fee , when computer will tell you in 5 min what is the problem".

Yes I am just going to seat on mu ass and computer will do everything for me, bla , bla, bla. Then I have to explain for about 30 min the money that they will pay it is diagnostic time that I have to spend on car and computer will just direct me what I need start diagnosing .
 

glitdi

Veteran Member
Joined
Dec 28, 2009
Location
West Coast Canada
TDI
Tdi asv motor in a mk3 golf, om642 in a wk jeep
Thanks for the info guys.. and yes oilhammer your post was a great read... mil lights and how people react to them is always so funny.
Light turns on person starts panicking like the sky is falling... Or drives on it for 3 years and wonders why they need a new tranny, insert major component here _________.
 
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