fuel pump

C

c11gtr

Guest
just fitted fuel swirl pot and need to fit another pump under boot floor
what size pump do i need (ie pressure out put)


gordon
 

Fast Guy

Moderators
Staff member
So have you taken the one out of the tank or left it? It should provide the pressure you need. Or have you just removed the internal pump and require an external pump? :?
Are you sure you mean swirl pot? They are normally to take air out of the cooling system aren't they?
What I've seen people do before is put a low pressure high flow rate pump at the tank end, then use this to feed a collector (or whatever it's called) quite often in the engine bay area and then have a high pressure pump to feed from this to the engine. Is this what you've done?
Unless you're running big power and need masses of fuel I'd have thought the normal wahlbro uprated pump would do.
 
C

c11gtr

Guest
yes i mean swirl pot
the group n pump i have wont push the fuel through with enough pressure
the reason 4 the pot is when iam down to half tank of fuel it wont pickup on left handers
 
C

c11gtr

Guest
so what does your are do at 1/4 tank
most people with group N pumps have the same problem
got it sorted now with tank on empty can pull left hander with out it cutting out
 

Fast Guy

Moderators
Staff member
I think normal systems use the method I described above. A low pressure high flow pump from the tank to the swirlpot (which can be in the engine bay) and then a high pressure pump to feed the engine.
 
C

c11gtr

Guest
mine is external i spoke to pete at spec r and you do need another pump as the swirl pot drops to much pressure so you need to build it up again i have put it under the boot floor will get some pics and post them
 
S

Sirnixalot

Guest
carl has it right

higher pressure pumps arent designed to suck...they need to be submersed or have the fluid "given" to them.

A carbureted cars fuel pump first to supply the high pressure fuel pump.
 

ian c

New Member
air pump

c11gtr said:
yes i mean swirl pot
the group n pump i have wont push the fuel through with enough pressure
the reason 4 the pot is when iam down to half tank of fuel it wont pickup on left handers
can i ask - who fitted your pump?
i have fitted my own conversion - works a treat and even when its on fumes never ever cuts out...........
don't settle for shoddy workmanship - take it back and ask if you can buy a sticker for this pump mod ....you know the one......it reads "my fuel pump doesn't work when i turn left - unless i'm leaving shell"

Scheisters....
 

watoga

Member
Hi guys,

Sorry to bring up an old thread, but I've a similar question related to the tank -> swirl pot pump. Basically, I'm building an external fuel tank so the system looks like this:





I have a Bosch 044 in the "Pump 2" location, but am unsure of what type of pump I need for "Pump 1". Originally, I was planning on putting an identical Bosch 044 there, but was worried that the swirl pot being fed simultaneously by the fuel-rail return line *and* "Pump 1" would fill the pot faster than the return-line to the petrol tank could remove it?

I suppose a solution would be to make the swirl-pot -> fuel-tank return a thicker hose so it could flow more fuel, but everything is -6 JIC so this doesn't seem an option :doh:

What would people recommend? Should I fit a low-pressure pump as "Pump 1"??? Or not worry about it and fit another Bosch 044??? Or just ignore the swirl-pot completely for returning fuel and have it return directly into the fuel tank???

Any help would be very much appreciated!
Cheers,
Dave
 

Fusion Ed

Active Member
Something like a Walbro 255 will be fine. They will flow plenty for your needs when run with no restriction.
 

watoga

Member
Hi Ed,

The Walbro 255 would be classified as a "high-pressure pump", right? I suppose my main worry is fuel entering the swirl pot (from the engine-return line and from pump 1) faster than it can leave (via the tank-return and pump 2 hoses) and causing problems. Am I being too cautious? I suppose my main concern is: Does "Pump 1" need to be less powerful than "Pump 2" (ie, flow less volume or have a lower pressure)??? Or can they be the same???

Sorry for being stupid, but I don't want to cause unnecessary problems...........

Thanks,
Dave
 

PobodY

Moderators
Staff member
Surely the idea is just to keep the swirl pot full and keep a reservoir for pump 2 so it never sucks dry?
I would have thought you'd be ok with the same pump for both; as long as you let it prime before you start the car it would fill the swirl pot before pump 2 starts putting anything into the injectors.

I would have thought that if you do get to the point where you're putting more into the pot than you're taking out, it will squirt like buggery back into the tank... which isn't really a problem.

This isn't an area I have any real knowledge of; I'm working purely on my cursory knowledge of fluid dynamics...
 

watoga

Member
Hi PobodY,

I would have thought that if you do get to the point where you're putting more into the pot than you're taking out, it will squirt like buggery back into the tank... which isn't really a problem.
Yeah, I thought a build-up of pressure inside the swirl pot would just cause the excess fuel to squirt really fast back into the main tank. However, if "Pump 1" has a safety cut-off of 8 Bar, does this mean the pump simply stops working until the outlet pressure is reduced to less than 8 Bar (ie the level inside the swirl pot has decreased)? Then it can pump fuel again? Or does the pump constantly hitting it's safety cut-off cause it long-term damage?

But of course 8 Bar (116 psi) seems quite a lot of "excess" to have, and I'd not be over confident in the hose/fittings taking this pressure constantly. Perhaps I'm wrong though, and this isn't a lot of pressure going through a fuel system?

I'm just curious and any help/feedback is very much appreciated!

Cheers guys,
Dave
 

stumo

Active Member
Like Ed said a Walbro will be fine in the tank.

As long as the return from the swirl pot (SP)to the tank is at the top of the SP you should be fine as the SP will always be full.

You can use the same size pipes (or even go down a size on the return) to and from the SP to tank and you won't have any pressure problems in the SP.

Looking at your picture, you'd be better swapping the two returns....the return to the tank at the top and the return from the pressure reg to the side of the SP.
 
Top