Lift Pumps: What are they doing, anyway?

robnitro said:

Thanks
Yeah I see now, the images made the page so wide that I couldn't see on my screen, lol.

If you log group 04, you can see timing req, timing actual, and n18 duty cycle. If they don't match and the n18 duty cycle is way high, that means the pump is either losing pressure, static timing too low, or the case relief valve might have a problem.

Also interested to see what you get at higher rpm. Even without load is a good test with the pressure/vac gauge because the IP vane pump flow is directly related to RPM, not fueling. Internal pressure is regulated by the case relief valve.

Click to expand...

Sorry about the wide pics. I tried to resize them when I posted but the forum tool to do that doesn't seem to work.

I did manage to record some logs before the laptop died. I'll post them once I get off work today. I logged start of injection (specified and actual), throttle position, boost, fuel consumption, fuel temp. One interesting thing I did notice was the highest number logged for fuel consumption was 25l/hr, which is still only 6.6 gallons (my lift pump is rated for 45 gph). That was at 100% throttle going uphill in 4th. So even if the vane pump outpaces my lift pump(that would yield a vacuum reading on my fuel feed lines with the lift pump on), I am still getting plenty enough fuel into the motor. I did decide to remove the oil pressure shut off and just run the pump on key on, because in low rpm situations (parking lots and such) I could hear the relay clicking on and off a little quick for my liking. I dont want to kill the relay with too many on off cycles.

One key thing to remember here is that pressure can only be made with a restriction, not a pump. All the pump does is displaces a fluid. In most cases (gasser efi setups) that restriction is the fuel pressure regulator. The regulator is what allows the pump to build pressure in the first place. So, with any fuel pump, whether its a lift pump, efi fuel pump, or even the HPFP on my 2011 CR, if you were to run it without some sort of regulator or restriction, its still not going to build pressure at the outlet.

So that begs the question, what is really causing my system to build pressure in the first place? The filter, and the IP are the regulators in our case. Does the vane pump in our IP allow for flow through? If it does not, fuel may just be flowing right across the filter and back out the return and that is whats allowing it to build pressure. I would like to tee my pressure gauge in AFTER the filters next time and see what I read there, because there will be a drop across the filters, and even though I didn't see a vacuum BEFORE the filters, I may see one after.

Either way though, the way I look at it, as long as my system holds some positive pressure under the highest fuel demand, my lift pump has a high enough flow rating to work with my setup. If at any point during high fuel demand, my system goes to a vacuum, that would completely defeat the purpose of having a lift pump, because that would show the pump cannot keep up in the exact situation I need it most. I am also thinking about adding a flow meter to see what ACTUAL flow is rather than running all my numbers off of rated flow.

Sent from my Bosch ECU via VAG COM

What is the N18 valve and what does it do?

Sent from my Bosch ECU via VAG COM

bassman5066,

The injection pump pumps a lot more fuel than the actual consumption, it just returns excess fuel to the tank. It is significantly more than 6.6gph especially considering that some of us are running 2-2.5x stock fueling and there is still more available.

The injection pump itself is the restriction you're after which causes pressure to build. Internally to the pump there is another restriction which causes 100psi pressure to build, the reason timing problems are had is when there isn't enough fuel at the inlet of the pump to build 100psi case pressure.

Its not the N18, but N108 he's speaking of which is the timing advance solenoid

I'm running a stock IP (is that 9mm or 10mm on the 1z?) With PP520 nozzles and a stage 3 Malone tune for 18 psi of boost on the stock turbo.

Quick question. What is the gph/psi rating of your pump?

Sent from my Bosch ECU via VAG COM

10mm on 1z.

Not sure what the gph rating is on a PD lift pump but I am told they hold 6-8psi pretty well.

Oops, n18 is not related (it's the egr valve solenoid- looks like the n75).
As Jfettig corrected, it's the n108 on the IP.

Yeah, the issue is that if the pump can't keep up, it ends up being worse than without the pump (but you have a bypass- so it's a wash). The IP flow in = out + fuel injected. So, even if you are barely using fuel, it is pumping a lot. It is a displacement pump, which means the flow is directly related to the speed of it. If it doesn't get the flow it needs, it ends up having cavitation inside, which affects case pressure/timing. That's why it can suck fuel from all the way back!

robnitro said:

Oops, n18 is not related (it's the egr valve solenoid- looks like the n75).
As Jfettig corrected, it's the n108 on the IP.

Yeah, the issue is that if the pump can't keep up, it ends up being worse than without the pump (but you have a bypass- so it's a wash). The IP flow in = out + fuel injected. So, even if you are barely using fuel, it is pumping a lot. It is a displacement pump, which means the flow is directly related to the speed of it. If it doesn't get the flow it needs, it ends up having cavitation inside, which affects case pressure/timing. That's why it can suck fuel from all the way back!

Click to expand...

OK, I will do some group 04 logging as soon as i get the chance. It's rainy today and I just had a small fire in my garage last night that requires some major cleanup, so that may not be as soon as I like.

I think a basic test that would hold true is what I mentioned in my last post. Tee a vac/psi gauge in the feed line to the IP after the factory filter (the 12 micron one on my drawing) in order to factor in pressure drop across the filter, and if it holds positive pressure all the way to 5000 rpm, I'll be happy. If not, that means the vane pump can still pull more than a 45 gph pump can push, so its time to get a bigger one.

Also curious how these numbers may or may not change with a larger IP. Does the 11/12mm IP have a larger transfer pump, or is it the same as the 10? What is the 10/11/12mm number referring to exactly?

Like I said, I will do some more logging as soon as I find my power inverter to power my junk laptop for more than 10 min, and I will also have my girlfriend sit in the pass seat taking a video of the vac/psi gauge that will be sticking out of the hood for testing, while pressing the marker button on VCDS every 30 seconds so I can reference the vac/psi gauge readings to the VCDS logs. Because that's what girlfriends are for, right?

Here is the log that I did manage to get. I will just post the xls file, because I tried graphing the fuel timing like you guys did, and just couldn't get it to work in openoffice, so maybe one of you could help me out with that.

http://www.4shared.com/office/QzUvNALZ/fuel_pressure_log.html

You just need to click on the link and hit "download", not "priority download". I didn't want to pay for a premium membership just to share a file.

Another question, when the engine is off (IP not spinning), is it designed in a way that allows for flow through if the external lift pump were on? Just wondering.

Yep, fuel goes through still but slowly, and it also flows a bit through the injector small lines. When I swapped IP's I used the lift pump to bleed it.

The 10/11/12 refer to the part that pushes the fuel to the injector, the plunger that gives huge pressure.
I believe the vane pumps are the same, same pressure.

robnitro said:

Yep, fuel goes through still but slowly, and it also flows a bit through the injector small lines. When I swapped IP's I used the lift pump to bleed it.

The 10/11/12 refer to the part that pushes the fuel to the injector, the plunger that gives huge pressure.
I believe the vane pumps are the same, same pressure.

Click to expand...

OK, I was just wondering where the 4 psi number was being generated from with key on/engine off(I.e. I wasn't sure if the pressure was being generated across the factory filter or the IP).

Is that part called an intensifier piston or something like that? I should have paid more attention when we were learning about rotary injection pumps in diesel school lol. Interesting that the internal transfer pumps are the same size. That means we should just have to find one lift pump that keeps up with the vane pump, and that should work for all the possible IP and injector combinations for our cars.
Another question, how would a (nonregulated) lift pump affect fuel timing in a fully mechanical pump with a throttle cable? Just wondering for a friend.

Looks like this fire in my garage is gonna tie me up for the next 2 weekends so no testing for me till that gets done. I got serve pro at my house tearing the garage apart and cleaning the smoke smell out of the house, then I gotta rehang drywall and replace a few studs that burnt up this weekend. Then paint the following weekend. It never ends. The joys of home ownership :banghead:

Sent from my Bosch ECU via VAG COM

hi
i have question for all,but one member prefered---Fix_Until_Broke
i instaled pd lift pump in tank,conected all fuel lines like original,or do i need to do some mod?maybe fuel cooler?
but! how do i conect the pump to the electric ,ive read somwhere that i need i signal + from relay 109,is this enough?so how is the wiring diagram for this mod? (golf 3 tdi afn,11mm pumphead)
liftpump provides so much fuel pressure,if i conect it to constant +12v it never stops pumping??? do i need some fuel pressure sensor to control in on-off or when it reaches pump operating pressure it stops alone????
please for help!

The pump is designed to run 100% of the time and should build ~0.5 bar (7 psi).

You should use a relay to power the pump - something like this

There are schematics on the forums as well if you search for them. I used the signal to the injection pump shutoff solenoid as the trigger for the relay.

For drejck
this install guide might help

http://idparts.com/downloads/PDLiftPumpInstallGuide_v1.5.pdf

thanks,and yes i mean it like this,but i want to know when i turn on key but dont start car, the pump wil run-work for all the time or wil stop when reaches max-working pressure.beacose i sometimes only turn on key but dont start car an dont want the pump runing all the time,with no use.

Relay 109 turns off automatically after about 5 seconds if the car is not started. It also cuts off fuel if an airbag deploys. It's a perfect trigger for the relay.

thanks that i need to know

I am preparing to install a lift pump on my 2002 ALH Jetta.

I have read the PDF from IDparts and it was very helpful.

I do not have the "relay box" that is mentioned in the IDparts instructions.

I believe in late 02 they were eliminated and the relays moved elsewhere.

I was going to use the OEM 53 relay, socket, and wires as I already have them laying around in my garage.

Since I do not have the "relay box" I am just going to go with a 30 amp bosch relay with my own wires.

Is the Black / White fuel cutoff solenoid wire still available in the "wiring plenum" on the 02 - 03?

Does anyone have any recommendations as far as where to mount the relay?

I am just looking for any ideas other members have come up with.

pump

I would not buy the grey and white in tank fuel pump that thing is garbage Got mine form a vender who got me a real great deal on one, installed it and only lasted about 2 years. Again as with others, no warning, pump just died and car stalled, I think this is a severe safety hazard. imagine gowning downhill around a mountain highway and you reach a nice curve, engine dies, power steering goes out, you have limited vacuum for brakes, you are now in real danger. A skilled driver/mechanic may not panic and get the car to safety, but others might not be so lucky. has this scenario ever played out? i couldn't say but its just like running out of fuel except you have fuel! Not to mention, the prices being changed for these pieces of garbage are pretty outrageous!!. I say stick with the yellow original oem pump design that even if the pump fails the engine can still pull fuel and you can get to safety. I am not a vendor and I do not advertize for any vendors or business, but rock auto has the yellow original style pump, for $165.00 with a lifetime warranty I mean seriously guys you cant beat that at all

I'll be installing mine as soon as it arrives. Also check out the rated specs on the pump itself:

Improved harness connector eliminates any known OEM problems
Insert-Molded valve housing for improved flow
Patented check valve reduces noise
Upgraded seals for consistent pressure for multiple fuel blends
Ceramic card reader ensures accurate fuel gauge readout
Brass jet pump orifice precision machined for consistent performance
Dual zone strainers for maximum filtration
Upgraded Isolator feet offer improved noise damping over OEM

Gasket Included N
Inlet Count 1
Inlet Type Strainer
Item Grade Standard Replacement
Maximum Free Flow Rate (gph) 70
Maximum Pressure Rate (psi) 12
Minimum Free Flow Rate (gph) 60
Minimum Pressure Rate (psi) 10
Outlet Count 1
Outlet Size 5/16
Outlet Type Quick Connect

http://www.rockauto.com/getimage/ge...tex/E8668M-1.jpg&imagekey=2567384-0&width=500


Those specs should more than meet any needs of the internal vane pump on the IP

madcowintucson said:

I would not buy the grey and white in tank fuel pump that thing is garbage Got mine form a vender who got me a real great deal on one, installed it and only lasted about 2 years. Again as with others, no warning, pump just died and car stalled, I think this is a severe safety hazard. imagine gowning downhill around a mountain highway and you reach a nice curve, engine dies, power steering goes out, you have limited vacuum for brakes, you are now in real danger. A skilled driver/mechanic may not panic and get the car to safety, but others might not be so lucky. has this scenario ever played out? i couldn't say but its just like running out of fuel except you have fuel! Not to mention, the prices being changed for these pieces of garbage are pretty outrageous!!. I say stick with the yellow original oem pump design that even if the pump fails the engine can still pull fuel and you can get to safety. I am not a vendor and I do not advertize for any vendors or business, but rock auto has the yellow original style pump, for $165.00 with a lifetime warranty I mean seriously guys you cant beat that at all

I'll be installing mine as soon as it arrives. Also check out the rated specs on the pump itself:

Improved harness connector eliminates any known OEM problems
Insert-Molded valve housing for improved flow
Patented check valve reduces noise
Upgraded seals for consistent pressure for multiple fuel blends
Ceramic card reader ensures accurate fuel gauge readout
Brass jet pump orifice precision machined for consistent performance
Dual zone strainers for maximum filtration
Upgraded Isolator feet offer improved noise damping over OEM

Gasket Included N
Inlet Count 1
Inlet Type Strainer
Item Grade Standard Replacement
Maximum Free Flow Rate (gph) 70
Maximum Pressure Rate (psi) 12
Minimum Free Flow Rate (gph) 60
Minimum Pressure Rate (psi) 10
Outlet Count 1
Outlet Size 5/16
Outlet Type Quick Connect

http://www.rockauto.com/getimage/ge...tex/E8668M-1.jpg&imagekey=2567384-0&width=500


Those specs should more than meet any needs of the internal vane pump on the IP

Click to expand...

Which pump are you referring to? Which engine does your car have? Assuming rotary VE IP style engine...

The facet inline pump I got (more or less a carbureted gasser pump) allows for pull through. Meaning fuel still gets to the IP regardless of if the lift pump is operating or not. Even if your pump doesn't allow pull through, you can simply design a bypass circuit around it using a few check valves. This will allow fuel to be pulled around the lift pump in the event of failure. I believe some PDs that experience lift pump failure will still run as well.

There is also a documented mod for the lift pump that will allow fuel flow even if it does go out. Simple to do too and it works. Search will reveal the setup.

I have a 2001 golf. Yes I am aware of the modification. Alot of work and trouble just to bandaid a bad design to begin with, but to each their own. The reason I bought the white/Grey garbage in the first place was because I read all the posts on here convinced the other one no longer was available (no suffix pump). Not only is it available, it's cheaper, has a lifetime warranty, and no mods required. This is just the rout I am going to go. Also before my pump actually died I was noticing a large drop in fuel economy, particularly during hi (above 90) ambient temps. At night my fuel economy would go back up. Now that my pump is out of the loop my fuel economy is back. I am talking about a 10 mpg difference before and after removing the bad pump. So in the day I would be lucky to crack maybe 35 mpg but at night it would approach 45. Now with no lift pump I get 43 daytime and about 55 night time. That's about right for my car. Point is, why would anyone go through the trouble unless they just want to experiment? Which is perfectly fine o totally get it. So how's the facet pump working out?

madcowintucson said:

I have a 2001 golf. Yes I am aware of the modification. Alot of work and trouble just to bandaid a bad design to begin with, but to each their own. The reason I bought the white/Grey garbage in the first place was because I read all the posts on here convinced the other one no longer was available (no suffix pump). Not only is it available, it's cheaper, has a lifetime warranty, and no mods required. This is just the rout I am going to go. Also before my pump actually died I was noticing a large drop in fuel economy, particularly during hi (above 90) ambient temps. At night my fuel economy would go back up. Now that my pump is out of the loop my fuel economy is back. I am talking about a 10 mpg difference before and after removing the bad pump. So in the day I would be lucky to crack maybe 35 mpg but at night it would approach 45. Now with no lift pump I get 43 daytime and about 55 night time. That's about right for my car. Point is, why would anyone go through the trouble unless they just want to experiment? Which is perfectly fine o totally get it. So how's the facet pump working out?

Click to expand...

Car has been sitting waiting on an engine rebuild. But worked for the 6 or so months I ran it. Pressure testing shows that I may want to go with the next higher flowing facet pump next time. Mine was reading 0.5 psi at 4500 RPM so it wasn't providing much of a boost to flow. Read about 5 psi with key on engine off, 3 psi at idle

There are a lot of us running the Grey/White VDO units with no issues and for many years now. It sounds as if there was an issue with yours MadCow which shouldn't necessarily condemn them all.

I cannot say why mine failed, I can only say I would never buy a design like that if a better, cheaper, lifetime warranty unit was available. The Grey/whites do come with a 12 month warranty if I am not mistaken, maybe some last many years (many being completely subjective), and yes i would totally condemn all of them and the design team and anyone else involved in that project lol. But I do not condemn anyone who bought one, just trying to help out fellow tdiers with options and my personal experience. If I had it my way I would drill and installed a sump on the bottom of tank and install the fuelab vortex setup and call it done haha. Still can't beat lifetime warranty though but the brushless pumps should last 20000 hours and that's way longer than I will own the car.

By the way, I wouldn't run any fuel pump unless it flowed at least 70gph and put out 7 to10 psi.

madcowintucson said:

By the way, I wouldn't run any fuel pump unless it flowed at least 70gph and put out 7 to10 psi.

Click to expand...

The vane pump inside the IP is still going to flow the same amount regardless. The point of a lift pump is just to keep that IP well fed.

You don't have any pressure without a restriction. In my case the restriction was the filter and IP itself. I ran 5/16 lines from the tank to the motor when I installed the pump. It went tank > pump (mounted under the car right in front of the tank) > 10 micron pre filter > factory filter. The rest from there was all stock down to the thermal t in the filter. I measured pressure between the pre filter and factory one.

Running the PD in tank pump also isn't an option for me because I have a MK3 tank, so it won't fit. The current pump on the car in question will be going on my work beater and I will be getting a bigger inline pump.

If you can't get a high flowing pump, but want to keep the IP pressurized try what I have been using:
http://forums.tdiclub.com/showthread.php?p=3767008#post3767008
No problems for 2 years and counting.

Basically this setup gets rid of the need for high return flow. You return 1/4 of the fuel and recirculate the rest through the filter. Pressure wise, there are no problems at all. At 4k rpm, I measured 6 psi at the inlet to fuel filter. 6 psi to the IP, 6.5 psi on the IP outlet that goes to T, and 1 psi on the return line- because of the kind of restrictive viton check valve I use, it takes 1 psi to crack open. Remember, you don't have to drive at WOT to test your fuel pressures, the vane pump will flow XX at YY rpm whether you are at WOT or just revving in N. Only a tiny fraction of the fuel that goes through the pump gets used by the injectors spraying even at WOT.

Only in summer I run the fuel cooler just don't want the fuel that recirculates to get too hot. But 1/4 of that fuel is coming from the tank anyway.

Somebody say don't use lift pump for vp37, other say use high pressure liftpump with pressure regultor. So which one say true?
With lift pump 0,5 bar 120l/h i have better Nm on midrpm, butwithout i have the same upper rpm.

jabcok20 said:

Somebody say don't use lift pump for vp37, other say use high pressure liftpump with pressure regultor. So which one say true?
With lift pump 0,5 bar 120l/h i have better Nm on midrpm, butwithout i have the same upper rpm.

Click to expand...

120l/h is not enough. You need double that so you can mantain pressure in the higher rpms. I used this pump: 1K0906089A with a pressure regulator. Its from 2.0 TDI and can pump 215l/h on 0,5 bar. On the german ebay these cost just 30-40€. The only problem with these is you need a pressure regulator.

Can i use pressure regulator from petrol engine i mean those regulator for racing. Which one you use? Thanks this is very helpfull...