Electric lift pump pressure

[Rabbit TD]

I want to put a small electric lift pump on my T/D Rabbit.  What pressure do I need as a minimum and maximum.  Autozone has them for $45 and one is a 2 to 3 1/2 lb. and the other is 3 to 7 lb.  Do you need to or should you use a relay with these.  I just got off the phone with them and I don't know what brand they are but I imagine they are the small square type by Facett that I've seen advertized.  I'd just as soon use the 7 lb. one if that's ok.  Oh and one other thing, will these things let fuel to be drawn through them from the injector pump if they quit working?

[Rabbit on Roids]

you dont need tons of pressure. i have a 2 psi pump in mine and it made a HUGE difference. i can prime my system with a 2psi pump. like run it clear out of diesel, and it fires right back up. i just hooked it up to the wire that runs the stop solenoid. didnt up the fuse or anything. these things draw such little power that it doesnt matter.

[Rabbit TD]

you dont need tons of pressure. i have a 2 psi pump in mine and it made a HUGE difference. i can prime my system with a 2psi pump. like run it clear out of diesel, and it fires right back up. i just hooked it up to the wire that runs the stop solenoid. didnt up the fuse or anything. these things draw such little power that it doesnt matter.

Well I guss there is no sense getting the bigger one then as it probably just has to work harder to maintain pressure, I thought about just splicing into the solenoid wire too, guess I'll try that first.  Do you know if they will let fuel flow through them if they quit working though, that's my biggest concern actualy.

[Rabbit on Roids]

well, i think they flow if there is nothing clogging them and they are off. but when you add it, that is effectively the smallest orifice in the fuel system, and it catches anything small. my rabbit is currently in the shop sick, with just this problem. the lift pump took a *** on me and it wont pull fuel now. oh yea, you might not want to run anything besides pump diesel in that little lift pump. i was running WMO when my pump let go. im amazed that my rabbit will actually start cold on just motor oil.

[rabbid79]

Oh and one other thing, will these things let fuel to be drawn through them from the injector pump if they quit working?

Couldn't you just blow through the end of it when you take it out of the box at the auto parts store to examine it?  Not conclusive, but it should give you some idea at least.

[Pillow]

You would really have to check the manufactures web site to see how they rate it for "death flow".

I believe some of the Walbro pumps are diesel flow through rated.  Also the GM 6.5 lift pumps would work well, but have oddball end fittings. 

... I agree with Kevin though, the CIS fuel tank might be a great solution with its internal pre-pump.

[53 willys]

I am using the stock gasser VW lift pump...it supply's my VE with about 5-7 PSI.....

[vwjones]

well, i think they flow if there is nothing clogging them and they are off. but when you add it, that is effectively the smallest orifice in the fuel system, and it catches anything small. my rabbit is currently in the shop sick, with just this problem. the lift pump took a *** on me and it wont pull fuel now. oh yea, you might not want to run anything besides pump diesel in that little lift pump. i was running WMO when my pump let go. im amazed that my rabbit will actually start cold on just motor oil.

i'm running 4 psi for WMO too.  do you have a separate tank for WMO? thought I was the only one crazy enough to be buring it.  sorry, don't mean to hijack

[Rabbit TD]

Oh and one other thing, will these things let fuel to be drawn through them from the injector pump if they quit working?

Couldn't you just blow through the end of it when you take it out of the box at the auto parts store to examine it?  Not conclusive, but it should give you some idea at least.

Well I got a pump today at Advance Auto.  It's one of the small Mr. Gasket diesel 4-7 lb. types and has a 100 micron filter on it too.  I was concerned about if it woud flow fuel if it wasn't working but it feels like it will blowing through it. They had 3 different ones all the same price but I got the green one that's diesel rated just to be on the safe side.  I wanted to blow through it first but like everything else today it was in one of those sealed plastic packages that only Houdini could get open.  I always wondered how elderly people open some of this stuff as tough as some of it is.  I haven't got the electric hooked up yet but I did get to play with the mig welder making a bracket for it and mounted and plumbed it in.   I was thinking about just hooking it up to the glow plugs and just have it run to pressurize the pump to let it start easier but I imagine I'll hook it to the solenoid.  Are these newer ones like the older style that would buzz till they built up pressure and then just tic to maintain pressure?  I did touch the 2 wires to the battery just to see if it worked before I mounted it but I couldn't tell much just from that other than it works.  Anybody have any idea how long these things last if you just run regular diesel fuel with them or have any problems wih them otherwise?

[Rabbit TD]

I got my pump all done today and wired to the shutoff solenoid and it seems to be working fine.  I really don't see any difference in the way it runs yet but I wasn't having any problems with the injector pump to begin with.  I was expecting the pump to run then shut off after it built up pressure in the injector pump but it doesn't.  Then I realized that if I am right that it doesn't work that way, it fills up and then just lets the excess run out the return line back to the tank doesn't it?  Is it good for these pumps to run all the time like that, I know gasoline fuel injection pumps do and at higher pressure but are these 4-7 lb. ones designed for this.  Also is there any advantage to having one running all the time?  If not I might just connect it to the glow plug circuit to make sure the pump stays full when starting.  I already know fuel will flow through when it is not running but I might just pull the inline fuse first to make sure the engine will not be starving for fuel with the electric pump shut off.  This is a Mr. Gasket 4-7 lb. green diesel rated pump, solid state electronics if any of this information is helpful.

[Rabbit TD]

i just hooked it up to the wire that runs the stop solenoid. didnt up the fuse or anything. these things draw such little power that it doesnt matter.

Just for reference, the stop solenoid is un-fused, presumably so that the fuse doesn't blow while you're in the middle of railroad tracks or intersections, etc...  I would add a fuse to anything that gets power from there simply to avoid the increased risk of frying your electronics.

Yes that's what I did, I put a 5 amp inline fuse on the wire to the pump from the solenoid terminal.  It's right there at the solenoid so it's handy to check or remove the fuse.  What do you think about hooking the lift pump to the glow plugs instead just to fully prime the pump for starting purposes only unless there are advantages to leaving it run all the time the way it is?

[arb]

I have a cheap electronic lift pump on my conversion daily driver. It works GREAT for priming the IP if it is dry (fresh install) or the lines are removed and air gets in. I did not notice any change in drivability when its on. I did experience LOSS of power on the free way several times from the pump restricting the volume of fuel going through it. That ever was blocking it must have passed to the filter as after stopping, it would idle fine and drive again for a while. I disconnected it but have it ready incase I ever run out of fuel and need to prime the pump along side the road.

[Rabbit on Roids]

your pump is messed up then, these stupid little pumps will supply way enough psi and quantity to keep our pumps happy. my car never starves of fuel with the pump on. i gained power with it on. and i have my smoke level turned WAY up.