04 Jetta died yesterday, mechanic (not dealership) states fuel pump/sender unit in tank gave out. I did not even know this car had a fuel pump in the tank.

I've been using Bio for the life of this vehicle (4 years), B100 in warm weather down to B25-30 blends for colder weather. I cold test and blend accordingly, fuel passes 3/27 test, washed and dried well and stored a maximum of 4 months...
The funny thing is, I had just added 5 gallons of petro diesel to the tank 2 days before to a nearly empty tank and had not gotten around to topping off with bio (this is not a normal thing, I normally top off right away). I had driven about 60 miles total with about B5-10 when the car died (just out of my driveway after idling about 2 minutes). Temperatures mid 40's F (not cold). We had not had a cold snap recently.

I'm just wondering if anyone's had something similar, the mechanic isn't saying it's fuel related (good thing I didn't have much bio in there) but I can't help but wonder.
Thanks

Checked TDIclub. Seems others have had the "lift pump" go out, one as early as 46,000 miles. Problems reported with dino and bio both. So probably not bio related.
BUT, this would not explain why there's a slight fuel leak in the engine compartment (just noticed while hood was popped trying to figure out why it wouldn't start).

I love TDIclub. I just diagnosed a failing alternator pully (they even had a sound clip of one going bad!) This is something that has been intermittent for months and I've had it to the shop twice. The mechanic couldn't replicate the problem, so "couldn't do anything". The tire/battery shop even diagnosed it down one of the pullys when I had them check the alternator. 30 minutes on TDIclub and I'm pretty sure of the problem...

There is another fuel pump in the engine compartment, iirc. I migh thave read that others
running B100 have had them leak. I too have read of several PD tank pump failures. It might not be powerfull enough to handle B100. Did you save your failed pump? I would be interested to see if it was a mechanical failure or open or shorted motor winding or??


Ask Lug_Nut at TDIClub about PD fuel leaks and B100.

the 04 jetta's seem to have a problem with the pump in the tank. Matter of fact there is a recall on them. Something you might want to look into but obviously not have bio in the tank at the time. But to answer your question there is def. a pump in the tank with the sending unit thats the new style setup its not the lift pump injection pump like the old style jettas were

just an add to my last post. It still has two pumps they are just the new style incase that was confusing. The injection pump is under the hood and driven off the timing belt and the fuel pump in the tank is the one with problems. However the injection pumps on those are prone to leaking due to biodiesel my thoughts on this is that the seals are just not right for bio. If i had one to take apart i would try to reseal it with viton seals and see if that would help the problem. All the new style jettas seem to have the same issues when running biodiesel leaking and failing pumps

quote:

All the new style jettas seem to have the same issues when running biodiesel leaking and failing pumps

Since many PD intank pumps failed running diesel, and there were sufficient numbe rof these to warrant a recall, I don't think you can claim that pump failures are the result of bd usage.

The one exception is vwrobert51 reported several bd PD pump failures. It might have been a bad batch with thick glycerin that pushed an already weak design over it's limit.

Also, the switch from LSD to ULSD and the lowered aromatics caused hundreds of injection pump seals to leak in 2006-2007. So running diesel instead of biodiesel will not guarantee a leak proof TDI.