Any of you guys run a lift pump?

thechoochlyman

Vendor , w/Business number
Joined
May 7, 2015
Location
Campbellsville, Kentucky
TDI
97 Passat
I know it's unnecessary, at least in a mostly stock application, but with my recent bout of fuel filter/tank woes, it got me thinking about it. This is the quickest thing I could find that would seem to fit the bill - low pressure, 8mm ports. My old 1st gen has a VE pump as well, but it also has a block-mounted LP that pushes roughly 5 PSI. I just thought a LP on our 1Zs might give a slight performance boost.

I would probably install it under the hood, very close to the fuel filter.
 

twentyeight

Veteran Member
Joined
Jul 14, 2009
Location
Phoenix, AZ
TDI
1Z & ALH
Depending on nozzles and fueling requests, I don't think the stock pumps are starving for fuel. You could monitor the case pressure to watch what's happening, but if it's dropping on a mostly stock application I think it's more indicative of pump failure than design deficiency.

You could also watch timing in VCDS (group 4) requested versus actual. Because the N108 works on case pressure you can verify that the pump is able to maintain (at least some) case pressure if it can meet highly advanced timing when requested. In fact, after a bad batch of biodiesel a few years ago I received an N108 code going down the freeway when the fuel filter clogged; it was unable to maintain advance because it was starving for fuel. This is a pretty rough test, though; I don't know the precise pressures required to maintain advance versus efficiently injecting fuel.

That said, if that pump doesn't cause problems (wire it to the fuel cut-off solenoid for safety) I can't see it hurting anything. Make sure your fuel return hoses are in decent shape—*if you over-pressure the case it ends up coming out those lines.
 

thechoochlyman

Vendor , w/Business number
Joined
May 7, 2015
Location
Campbellsville, Kentucky
TDI
97 Passat
Good input.

On the note of starving the pump, I'm going to clean out my sending unit later today - I've had a power loss condition since last Friday. I haven't exactly been driving it hard whenever it's not wanting to go, but I'm mildly worried about potential pump damage from running it semi-starved.
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
The internal lift pump is more than adequate, the problem is elsewhere. I know a lot of people advocate for the external lift pump but unless the electric pump allows fuel to pass through even without power (if elect pump dies) you're just adding another failure point to the system.

Also, certain types of in tank pumps are vented since they only function to supply fuel to an accumulator and that introduces air into the fuel system, a system that needs to be completely sealed on a diesel.

Inspect your one-way valve on the fuel supply line to see if it's developed a problem. I would look at that before I'd start trying to muscle through it with a pressure pump.

Steve
 

BioDiesel'

Well-known member
Joined
Sep 15, 2013
Location
CT
TDI
1998 Jetta Elsbett single-tank, 230K WVO miles
I used to plug fuel filters regularly running wvo due to algae plugging the filters.
It causes a fuel restriction that is only perceptible when near full throttle.
Like going up hill.
It fells like a slight sag in power, like running into a sudden head wind.

If it gets real bad I get FIP CEL codes, 'control deviation ' iirc.

FWIW, my FIP pulls thick, viscous, wvo out of the tank w/o a need for a lift pump.
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
well you certainly don't *need* one. but if your power levels go up (and for convenience), i run one in my rabbit and mk3. they haven't been used in a while, and got by with a mr. gasket pump from autozone (never buy them again). but you can get a better facet pump on amazon for cheaper/similar price. pretty easy to mount inline in the engine bay before the filter (ideally with a cute little pre-filter before). the facet i'm fairly sure flows even if it "fails" but what fails means who knows. i'm quite sure any inline pump will still flow if it fails, unless it fails unexpectedly :)
 

apaustin

Veteran Member
Joined
Dec 9, 2010
Location
maryland
TDI
05 passat wagon, 96 B4V, 95 glx v6/96 tdi conversion, 97 b4v
My '95 glx conversion came with a pump in the tank. It was one of the many things that crapped out in the first 1,000 miles (and on and on). The '96 with its stock system runs flawlessly, by comparison.
 

vanbcguy

Veteran Member
Joined
Feb 22, 2013
Location
Vancouver, BC
TDI
'93 Passat - AHU mTDI with GTB1756VK
Fwiw it's actually not the best idea to install a pump right before the filter, at least according to the filter manufacturers. You want a smooth flow of fuel through the filter so it can do its job, the water separator in particular.

On my Jetta I have a big Racor marine filter - totally overkill. I have a Facet Posiflow lift pump mounted post filter. The pump is a "draw through" type which the IP can happily pull fuel through should it fail.

Sent from my XT1097 using Tapatalk
 

jhax

Veteran Member
Joined
Jan 24, 2012
Location
Golden, CO
TDI
96 Passat B4V, ALH engine out of a 2002 Jetta, some IE Rods and ASV Pistons. Nothing drivable yet though
I am going to install a PD lift pump in my mk2 with an ALH swap. I'm curious to know if I will no longer have to worry about re-priming the IP if I do run out of fuel with the lift pump installed?
 

vanbcguy

Veteran Member
Joined
Feb 22, 2013
Location
Vancouver, BC
TDI
'93 Passat - AHU mTDI with GTB1756VK
Correct - the lift pump will happily prime the IP. Makes filter changes really easy too!

What are you going to do about your fuel gauge?

Sent from my XT1097 using Tapatalk
 

jhax

Veteran Member
Joined
Jan 24, 2012
Location
Golden, CO
TDI
96 Passat B4V, ALH engine out of a 2002 Jetta, some IE Rods and ASV Pistons. Nothing drivable yet though
I have a guide on my computer at home that shows what to do I think. Forgive my ignorance but what is the issue with the gauge? Im using a AHU cluster from a Jetta if that means anything.
 

vanbcguy

Veteran Member
Joined
Feb 22, 2013
Location
Vancouver, BC
TDI
'93 Passat - AHU mTDI with GTB1756VK
The PD lift pump has a Mk4+ style fuel gauge. The later fuel gauges have the opposite relationship from the earlier ones - ie maximum resistance = full on one while maximum resistance = empty on the other. The result is that the fuel gauge on a Mk3 or earlier will move backwards when using the PD lift pump since the fuel level sender is integral with the pump assembly.

Sent from my XT1097 using Tapatalk
 
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