Lift pump...If...and what if....

[darrenjlobb]

Hey guys...

I seem to be having problems keeping the fuel up high, well was before...ive read about people using lift pumps to try and help?

Has anyone seen prooven gains with this?

Can you supply the pump direct with a pressurized line, or do you need a swirl pot or something, and if feeding direct will it do the pump any good being understand load holding pressure?

Cheers

[Rabbit on Roids]

my car ran much better after i added a small electric pump before the filter. never loses prime, and if you run out of fuel, no worries, just fill it back up and take off. definitely not a bad thing to add in my opinion. why would they put them on like every other diesel ever produced? cummins, fords, chevys, all of them have lift pumps.

[darrenjlobb]

It wont do the pump any harm having a pressurized input then? Or do i need a mini pot in the bay so its still suction feed to the pump? My lift pump is one ive put in the tank..not sure of pressure, but seems a little bit, if you hold finger over end you get a fair air build up behind it...

[cyrus #1]

I don't think you want any more than maybe 3-5 psi.  If you feed it too much pressure you will start to mess with the timing curve.

[burn_your_money]

You also need to make sure that the lift pump will not restrict fuel flow under high fuel demands. I don't know what the required GPH is though.

[truckinwagen]

do you think the stock in tank lift pump from a mk2 CIS gasser would flow enough?
supposedly they put out 5PSI

[burn_your_money]

I thought they were in the 15 psi range?

[truckinwagen]

I heard that the cis lift pump was 5psi and the Digi pump was higher as it only has one fuel pump not two like the CIS system.

but I have been wrong before, so...

[weejimmy]

lots of folk do this for running veg oil.
use a 4psi faclet? pump
just in line is the usual. fine at top end can flow plenty.

[Rabbit on Roids]

my lift pump will flow just fine, even when its completely off with just the IP to suck fuel through it. the injection pump uses way less fuel at WOT than what the pump puts out. my lift pump puts out atleast twice the fuel my IP could ever return back to the tank.

and as for the in tank pumps, mk1's dont even have a lift pump in the tank do they? all my gasser rabbits have an external pump right after the tank, and it puts out like 90 psi. but no in tank pump. my jetta has an in tank pump that puts out about 5 psi.

[darrenjlobb]

So im fine pressurizing the input line to the pump?... or do i need a regulator / pot in the engine bay...

[cyrus #1]

I heard that the cis lift pump was 5psi and the Digi pump was higher as it only has one fuel pump not two like the CIS system.

but I have been wrong before, so...

Digi cars still have two pumps.  The main pump doesn't make as much pressure as a CIS pump but I'm not sure about the transfer pump.

[Rabbit on Roids]

I heard that the cis lift pump was 5psi and the Digi pump was higher as it only has one fuel pump not two like the CIS system.

but I have been wrong before, so...

Digi cars still have two pumps.  The main pump doesn't make as much pressure as a CIS pump but I'm not sure about the transfer pump.

Basic CIS has one pump (usually earlier A1 cars), Electronic CIS has 2 pumps (later A1 cars and early A2), Digifant 1&2 also have 2 pumps (later A2 cars and early A3 cars) and all transfer pumps that ive read about put out around 5 psi or so. the in tank pump just pumps fuel to a smaller tank that the fuel pump sits in. the smaller tank is so that the pump is always surrounded by fuel, and fuel is what cools the fuel pumps. so you can be a cheapskate and run around with no more than 5 bucks worth of gas in your tank and not be overheating your fuel pump and killing it early. clear as mud?

[foxracer1]

 I have an mkII gasser in tank pump in my jetta. I used a gauge at the fitler once and couldn't get more than a few psi. The gauge i used may have been to blame. But it seems to have plenty of fuel flow across the RPM range. At any rate the pump is nice for filter changes.

 I'm gonna play with diff psi going in to the pump. Have heard around 15 helps up top with timing curve for added power. I have thought about using a GM TBI fuel pump as i have access to them and the TBI system pressure is 15-20 on 2.5l-5.7l engines, so with a regulator i have no doubt it will flow enough at 10-15psi for my 1.6l.

[darrenjlobb]

So having a smaller tank in the engine bay, which the lift pump just sends / returns to, and the injector pump sends / returns to would be a better idea?

Or doing the inlet / oulet pipe...i guess that would work...altho would the fuel not find ti easier to go this way than to the pump / starve the pump just the same,...