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Electric SU fuel pump
https://www.ausmini.com/forums/viewtopic.php?f=2&t=7688		 Page 1 of 2
Author:  Matt68 [ Tue May 31, 2005 10:50 am ]
Post subject:  Electric SU fuel pump
I have an electric SU fuel pump. I got it direct from burlen fuel systems a few years ago, it is the one with electronic switching, not points.

The problem is this, I think it needs to have a pressure regulator or something as there was a problem with the carbs running too rich. (twin SU 1.25", correct needles, brand new correct needle and seats.) I adjusted the carbs properly, and set the float level in the fuel bowls. I even set the floats so they should have cut off sooner, but still I would get fuel coming out of the air hole at the top of the fuel bowls, not while in the garage, just after driving. Pretty soon the plugs would foul with carbon.

Anyway, is it possible to change the pressure setting within the pump itself?

Are there any good in-line fuel pressure regulators that do a good job with low pressures?

Any other ideas?

Cheers
Matt
Author:  meeni [ Tue May 31, 2005 11:38 am ]
Post subject: 
i have the same problem as you with the same fuel pump, i think you do need a regulator, i dunno where to get them or what they look like though :(
Author:  simon k [ Tue May 31, 2005 12:20 pm ]
Post subject: 
I bought one for $60 at autopro in Goulburn, but I couldn't get the bugger to set properly so gave up on it, but same thing, fuel coming out of the carb breathers. I put a couple of bits of fuel line from the breathers to a plastic peanut butter jar cable tied to the crossmember near the wiper motor, after 5 laps at wakefield it was full :shock:

I never had a problem with it running rich though, that ought to be a mixture problem. The float should still stop the fuel coming through the needle and seat, to a point...

All of the race minis at winton had the same type of regulator as I bought from autopro, unfortunately I can't find a picture and don't remember the brand. It's round, with a dial on the top of it, simply fits inline with the fuel line, doesn't have any mounting points to screw it down to the body or anything.

I'll take a pic and get details at home unless someone else posts

BTW, SU is the brand name, if it's not an SU, then just call it an electric pump....
Author:  Matt68 [ Tue May 31, 2005 12:57 pm ]
Post subject: 
Quote:
BTW, SU is the brand name, if it's not an SU, then just call it an electric pump...


:D It actually is an SU pump, Made new by Burlen fuel systems who bought SU a few years ago. Same as the cooper s ones except it has electronic triggering (solid state) instead of the old points style triggering. Bought staight off Burlen Fuel in the UK. Good Mob. :wink:


Do you know what setting the pressure should be at? I've seen these regulators a while back when i had a facet solid state pump. I got rid of it when I found out it delivered 12 psi, and i was told by an old mini bloke who still races now, that 3 psi is all you need.

Thanks

Matt
Author:  simon k [ Tue May 31, 2005 1:00 pm ]
Post subject: 
Matt68 wrote:
i was told by an old mini bloke who still races now, that 3 psi is all you need.


yeah, that's what I was told too, the racecars at winton all seemed to be set at 4psi, they were all running webers and race motors, so 3 sounds about right for a road car.

I concede on the brand name issue ;)
Author:  Matt68 [ Tue May 31, 2005 1:21 pm ]
Post subject: 
Thanks,

I'll go for a regulator that i can set at 3psi.

Unless I hear different by tomorow (day off).... :wink:

Cheers
matt
Author:  simon k [ Tue May 31, 2005 1:24 pm ]
Post subject: 
Matt68 wrote:
Thanks,

I'll go for a regulator that i can set at 3psi.

Unless I hear different by tomorow (day off).... :wink:

Cheers
matt


the one I have is 0 to 6, so just what you need, and 9YaTaH took me to 6 places in Goulburn to find it - it was the only one (and last one) in town!
Author:  miniron [ Wed Jun 01, 2005 10:21 am ]
Post subject: 
:?
The SU pump only gives about 2.5/3 psi.
Make sure the flexible mountings for the float chambers have not hardened. Solid mounted SU float chambers are not good in 4 cylinder engines. Engine vibes/harmonics etc can cause fuel frothing and flooding.
SU carbs have a much smaller leverage ratio between the float and the needle and the float has less buoyancy when compared to other carbs. It doesn't take much to cause flooding. This tendency is increased if you use the large hole float needle and seat as there is more force from the fuel pressure for the float to overcome than with the smaller hole version. (Force=Pressure x Area)
Make sure you have the small size spring loaded float needle and seat. There are several different sizes and types of these. You need the small hole AUD9095 spring loaded "Delrin" needle type. It has a sort of cross shaped white plastic section with a spring loaded pin which contacts the float.
I've tried them all over the years and that is the only one that works reliably for me.

Edit: A bit more info re floats. Make sure the point where the needle touches the float is not worn. Any wear dimple here can also cause flooding. Also make sure you have the correct type of float.
There are or were 3 different types of floats about.
1st type has a metal arm and plastic float but the arm has only one bend. These replaced the original brass float on early HS type carbs. These used a float lid with different geometry to later types.
2nd type is similar to the 1st type but has an arm with a dog leg (2 bends) and is the type originally used on most OZ built Minis.
3rd type is an all plastic float which replaces the 2nd type.
With the 1st and 2nd type floats you can set the fuel level by bending the arm. On the 3rd type you have to fit 0.010" aluminum spacer washers under the float seat were it screws into the lid. (Washers are part No AYB0377)

Regards
RonR
Author:  drmini in aust [ Wed Jun 01, 2005 7:27 pm ]
Post subject: 
skssgn wrote:
Matt68 wrote:
i was told by an old mini bloke who still races now, that 3 psi is all you need.


yeah, that's what I was told too, the racecars at winton all seemed to be set at 4psi, they were all running webers and race motors, so 3 sounds about right for a road car.

I concede on the brand name issue ;)

Simon, that reg you bought (I was there that day) is a Purolator.. :wink:
Author:  kazjim [ Wed Jun 01, 2005 8:25 pm ]
Post subject: 
Well, i use a Holley Regulator (came with my Blue Pump) its VERY adjustable.....

The HIF-6 i have is apartantly very sensitive to pressure, and anything over 3psi freaks them out ...... well mine runs at a solid 3.5 Psi and then as boost comes on, fuel pressure rises 1:1 with boost pressure (my little mod to the regulator)

the holley is designed for 600HPish engines.... its adjustable enough for our little 100Hp jobbies !

about $90 at your local speed shop.....(then if you want the KazJim mods, just PM me !)
J
Author:  meeni [ Wed Jun 01, 2005 8:35 pm ]
Post subject: 
do you think that having one of these pumps without the regulator could be the reason my engine is running so bad, like it could be drowning in fuel? coul i see a pic of a regulator, i may have one, if not i will go out and get one!
Author:  kazjim [ Wed Jun 01, 2005 8:53 pm ]
Post subject: 
I'll refer you to one of the earlier responses to your question....

What do your plugs look like ?
Blowing black, nasty smoke ?
engine sound like "Ruuump, ruuump" ?

J
Author:  Chris [ Wed Jun 01, 2005 9:04 pm ]
Post subject: 
OK here is my two bobs worth. Be warned this is a bit of work and fiddly but works. Run a return line from somewhere between the pump and the carby and put a restrictor in this line that gives the desired PSI at the needle and seat. Sizing the restrictor can be a bit of a fiddle that's all. The return line can just be teed out the fuel line just beyond the pump and go back into the line between the tank and the pump. The restrictor is a round plug in the return line with a suitable sized hole drilled in it. Hook a pressure gauge onto the carby line while you are doing it to size the restrictor. It might take a couple of hours but it works.
Author:  benjamin [ Wed Jun 01, 2005 9:28 pm ]
Post subject: 
when i changed my fuel pump i my kept flooding to so i changed the float level problem solved :wink: thats with twin 1.25 s to
Author:  Matt68 [ Mon Jun 06, 2005 1:56 pm ]
Post subject: 
Thanks everyone,

Ron, so the SU fuel pump pressure should be OK, it's up to the needle and seat and the floats. The carbs had brass floats when I got them, and I since changed over to plastic floats with the one kink. I also had to change the fuel bowl lids as the ones I had were too 'short' and ended up puting the needle valve to far down into the fuel bowl. :?

I'll try to fiddle with the float heights again, an see if I have any more luck this time. I've gone from a 998 to a 1275, so it should use a bit more fuel anyway :wink:

Cheers
matt
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