In-Tank lift pump

blazen71

Veteran Member
Joined
Oct 25, 2011
Location
Wiskullsin
TDI
All Gone
Hello all. Something I've been thinking about with the B5.5 TDI's. Will they run if the in-tank lift pump fails? Does the tandem pump suck fuel if the in-tank pump fails?
 

pdq import repair

Veteran Member
Joined
Nov 6, 2016
Location
idaho
TDI
09 Jetta
I have seen them run fine with no issues, but if you replace a fuel filter or open the system in any way, restarting will be a long adventure.

I have two I can think of that have run years without the lift pump, discovered after a filter change. I have seen reports of problems due to lack of lift pump, but have not experienced it without other underlying fuel system integrity problems.

We used to put lift pumps on the old rabbit diesels with injection pump seal issues. They would run fine, but bleed back to the tank overnight as the seal sucked air.
 

Windex

Top Post Dawg
Joined
Apr 1, 2006
Location
Cambridge
TDI
05 B5V 01E FRF
Mine had a bad relay for a time, and would run just fine until the fuel got low. It would need extended cranking in the morning cold below 1/4 tank, but other than that you wouldn't know there was a dead lift pump.
 

blazen71

Veteran Member
Joined
Oct 25, 2011
Location
Wiskullsin
TDI
All Gone
Thanks for the replies. I had the rear seats down yesterday and noticed that when i cycle the key the pump made an almost gear grinding sound. Then again when I started it. Today I don't hear anything. If i'm correct, I believe it is a gear type pump. I bet it is shot.
 

blazen71

Veteran Member
Joined
Oct 25, 2011
Location
Wiskullsin
TDI
All Gone
I have seen them run fine with no issues, but if you replace a fuel filter or open the system in any way, restarting will be a long adventure.

I have two I can think of that have run years without the lift pump, discovered after a filter change. I have seen reports of problems due to lack of lift pump, but have not experienced it without other underlying fuel system integrity problems.

We used to put lift pumps on the old rabbit diesels with injection pump seal issues. They would run fine, but bleed back to the tank overnight as the seal sucked air.
I have replaced the fuel filter but filled the new one with PowerService first. I had no issue with starting after the change.
 
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