In tank pump - 3 wires?

beanboon

Member
Joined
Oct 19, 2004
Location
Jacksonville, FL
My 04 PD failed me for the first time this morning. I got about a block from home and it stalled. Just like I shut the engine off, but the radio and everything stayed on. It turns over, but will not start.

My glow plug light does come on.

I pulled the cover off of my fuel tank to investigate. I turned the key but did not hear the pump whirring, but it's only supposed to whir long enough to build up the proper pressure in the fuel lines (no?). So maybe it was already built up.

I pulled the plug off of my fuel tank to check voltages. You're supposed to have 4 wires, and the outer two are power and ground (brown is ground). Oddly enough the brown wire appears abandoned. There is a floating spade connection on the tank, and no female receptacle in the plug.

I put 12v to the two outer connections directly on the tank and the pump did run.


I called the dealership to ask about parts and the service advisor asked about my timing belt. I have 93,700 miles on it. He asked if the car is turning over faster when you try to start it, because you may have skipped ahead a notch. It seems like it's turning over faster, but hard to say as it always started right up before so I never heard it turning over.

Funny thing is I have an appt to go have my belt replaced tomorrow (NOT at the dealership).

Does it sound realistic that my belt could have slipped and be causing this?
And what's the deal with this power connection to the pump?





 

weedeater

Top Post Dawg
Joined
Mar 17, 2001
Location
Reston, VA
TDI
Jetta, 2001, Baltic Green
Not having the wire diagram in front of me, I would guess that the other connection is the float. So there is a common ground (one of the other connections. And they're tied together on the other side of the connector.

So, checked the fuses?
 

beanboon

Member
Joined
Oct 19, 2004
Location
Jacksonville, FL
Yes, I checked the fuses. I looked at them all and physically swapped 28 and 29 (pump and rear wiper) to verify they were good. (They were).


I just went out and applied 12v directly to the pump for about 10 seconds and was able to start it. It was hard to start though, had to turn over almost 10 seconds.

Plugged the car harness back in and no start.

12v directly into the pump again (requires about 10 seconds) and it started again (after cranking about 7-10 seconds).

I was able to remove the 12v from the pump and the car did not stall (at idle, I'm not going to drive it around right now!). It just wouldn't restart without the pump being manually fed.

Did I get the right fuse? And why would it be so hard to start when normally it cranks up immediately??
 

gforce1108

Top Post Dawg
Joined
Aug 2, 2006
Location
Newburgh, NY
TDI
04 Jetta GLS BEW, 14 Audi A7 V6 TDI, 13 Porsche Cayenne V6 TDI
I haven't pulled mine apart to inspect, but it doesn't look like the 4th spade connection is floating on the pump. It looks like it melted. Same goes for the wiring harness end. It looks (at least in the pics) that there is a connector in there only it's blackened.
Can you see how many wires are in the harness to confirm?
 

beanboon

Member
Joined
Oct 19, 2004
Location
Jacksonville, FL
4 wires in the harness.

I've been trying to get a better look at the harness as it does appear as if a BLACK contact set is in there, but it appears uniformly black. Odd.
 

PDJetta

Top Post Dawg
Joined
Nov 6, 2003
Location
Northern Virginia
TDI
'04 Jetta GLS TDI Pumpe Duce Platinum Grey w/ Leather
The two smaller wires and connector pins are for the sending unit, the larger ones are pos. and neg. power for the pump. Brown is the ground for the pump. I highly suspect the female connector is messed up, from the picture you posted (one terminal is missing). Also, one of the outter terminals on the pump looks like it got hot and the plastic around it melted.

Check the wiring harness right before the female connector. All 4 wires should be there. You need to repair the connector, it looks like.

The pump ALWAYS comes on for a couple of seconds when the key is turned on and its always running when the engine is running, if all is working correctly.

--Nate
 

gforce1108

Top Post Dawg
Joined
Aug 2, 2006
Location
Newburgh, NY
TDI
04 Jetta GLS BEW, 14 Audi A7 V6 TDI, 13 Porsche Cayenne V6 TDI
If you look closely at the female connector (I downloaded the pic and blew it up), you can see that the terminal is there but it is discolored. I'd pretty much guarantee that the current draw from the pump overheated the connector and melted the male spade pin (may have been a bad connection to begin with). The female connector is discolored from arcing. Even if you repair the harness, you probably will not be able to make a connection to the pump. I'd replace the pump and repair the harness.
You might get real lucky by pulling the pump and inserting the spade pin into the harness while it's plugged in, but I'd suspect that the original pump problem will still be there.
 

2004STARWARSTDI

Top Post Dawg
Joined
Oct 19, 2004
Location
LAKELAND, FL
TDI
2004 Platinum Gray GLS Jetta / 2006 Silver Jetta with DSG
Question

BEANBOON have you ever run out of fuel or nearly so? Fuel pump needs fluid around it to cool it or it can overheat.:eek:
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
I also think that the pump is failing and pulling too much current, causing the overheating.
Can you measure the current flow during the run with your alternate power wires?

So I agree with gforce.
 

beanboon

Member
Joined
Oct 19, 2004
Location
Jacksonville, FL
I run it down to empty practically every time. It sucks that that might cause a problem. Seems like a normal practice to me.

Anyway, it certainly is melted and the female spade blackened. Jumpered it works fine. I'll have to order a new fuel pump (unless I can fashion something to get that spade back into the harness).


The prognosis: intermittent contact at the fuel pump caused the car to stall. The car will run without the pump, but not all the time.
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
Almost all modern electric fuel pumps will not take routine or periodic running dry. It is bad for them in many ways - lubrication and cooling being the main ones.
It has been that way for years. My 89 Ford warns not to do this as a practice.
So this is not specific to TDIs.
And this is why (in addition to potential damage to the unlubricated operation of the injectors, tandem pump and/or injector pump) that I ensure I never get too low in my fuel tank.

How many threads have you heard start out "I ran out of fuel..." or "I changed the fuel filter and did not refill the system..."(which has much the same impact) and then they proceed to tell a tale of woe?

The overheating of the connection could have resulted from a normal load and high resistance (poor) contact, or it could have resulted from an overload condition.

Before I started looking at a new pump, I would check the operating current of the pump you have. I can probably check mine to provide a data point, if no one can find what it should run.
If your pump has normal running current, then I would just attempt to repair the pump portion of the connection, and replace the wiring connection. This could save a couple hundred bucks, and it would give us some insight into the failure.

DanG
 
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