I've got a 3.5 liter, with Weber 38/38s. What electric fuel pump is recommended? Fuel pressure regulator to go with it?
Best Electric Fuel Pump?
- Thread starter Jellobmw
- Start date
Not sure what the pressure requirements are for those webers, but the Carter P4070 is often suggested for the DCOEs.
This is the regulator I plan on running on mine at 3.5 psi
http://www.summitracing.com/parts/igs-ng1081
This is the regulator I plan on running on mine at 3.5 psi
http://www.summitracing.com/parts/igs-ng1081
jmackro
Well-Known Member
I believe the downdraft Webers take the same pressure as DCOE's, say around 3-4 psi. I don't think you need a separate regulator if your pump is rated in that range.
What ever you get it needs to be low pressure 3,5psi max but high (ish) volume.
Remember carbs need no pressure as such to work, the only pressure needed is to get the fuel to the float bowl, from there the fuel is drawn into the engine by vacuum.
Too much fuel pressure and/volume and you end up overwhelming the float valve, flooding the float camber and then it all goes pear shaped.
The best advise I was ever given by the Weber guru here in NZ when I was running DCOE's on my track car was to have a return line to bleed of any extra volume of fuel.
Remember a mechanical pump, pumps relative to engine speed, at idle not much fuel required, pump only running slowly, low volume of fuel supplied, High revs, high pump speed, lots of fuel supplied.
Electric pumps are one speed/volume all the time, and that speed needs to be high enough to provide the right volume of fuel at max engine speed, problem is this is way to much at idle and low engine speeds.
You need to be able to get rid of that excess fuel, and thats when the return line comes in.
The return line setup that he recommended was very simple and worked a charm
In order,
Tank
Pump
Filter
Pressure regulator
Carbs
And then at the last carb a return in the fuel line back to the tank.
The trick is to block the return line with a plug with a 1mm hole in it (I made my plug, using a bolt that wound nicely into the rubber fuel line, drilled a 1mm hole up the length of this (10mm 3/8 ish) and cut this bit off, also need to put a hacksaw cut across the end of this plug so you can wind it into the rubber fuel line with a screw driver) this hole is just big enough to bleed of any excess volume back to the tank, but not to effect the fuel supply to the carbs.
Anyway, that's my 5cents worth, I guess some will agree and some wont, but it worked very well for me and had absolutely no problems with fuel seeping from my carbs after I did this.
I had so much excess fuel that it used to drip out of the carbs (DCOE's) mouth and ended up causing a engine fire, and believe me you don't want one of those!
Others will chime in with there thoughts I guess.
Good luck
Remember carbs need no pressure as such to work, the only pressure needed is to get the fuel to the float bowl, from there the fuel is drawn into the engine by vacuum.
Too much fuel pressure and/volume and you end up overwhelming the float valve, flooding the float camber and then it all goes pear shaped.
The best advise I was ever given by the Weber guru here in NZ when I was running DCOE's on my track car was to have a return line to bleed of any extra volume of fuel.
Remember a mechanical pump, pumps relative to engine speed, at idle not much fuel required, pump only running slowly, low volume of fuel supplied, High revs, high pump speed, lots of fuel supplied.
Electric pumps are one speed/volume all the time, and that speed needs to be high enough to provide the right volume of fuel at max engine speed, problem is this is way to much at idle and low engine speeds.
You need to be able to get rid of that excess fuel, and thats when the return line comes in.
The return line setup that he recommended was very simple and worked a charm
In order,
Tank
Pump
Filter
Pressure regulator
Carbs
And then at the last carb a return in the fuel line back to the tank.
The trick is to block the return line with a plug with a 1mm hole in it (I made my plug, using a bolt that wound nicely into the rubber fuel line, drilled a 1mm hole up the length of this (10mm 3/8 ish) and cut this bit off, also need to put a hacksaw cut across the end of this plug so you can wind it into the rubber fuel line with a screw driver) this hole is just big enough to bleed of any excess volume back to the tank, but not to effect the fuel supply to the carbs.
Anyway, that's my 5cents worth, I guess some will agree and some wont, but it worked very well for me and had absolutely no problems with fuel seeping from my carbs after I did this.
I had so much excess fuel that it used to drip out of the carbs (DCOE's) mouth and ended up causing a engine fire, and believe me you don't want one of those!
Others will chime in with there thoughts I guess.
Good luck
+1 except it's recommended that the filter go before the pump after the tank, this keeps crap from killing the pump.
Did you run a hose from the last carb in the line, connecting it with a fuel fitting tee instead of the usual end fitting?
Did you run a hose from the last carb in the line, connecting it with a fuel fitting tee instead of the usual end fitting?
On my setup on the DCOE's, I used 2 x of the double weber/dellorto fuel inlet fittings (the one that the first and middle carb uses) on all the carbs, if you have these you can drill and tap the one you are using for the return line outlet and screw the return line plug into this instead of putting it in the rubber hose.
Not sure what the setup would be with 2 x if the standard type webers/zeniths, but I'm sure it wouldn't be too hard to sort out
Polariscsl
Well-Known Member
I run twin facet red tops in series to provide maximum volume at the same pressure restricted by a pressure regulator with integral filter. This setup uses fia hose fittings with 10mm bore.
This is for 270 bhp or so - in a standard car I ran one of these pumps on triple webers.
This is for 270 bhp or so - in a standard car I ran one of these pumps on triple webers.
For my triples I run a Carter P4070 and Holley 1-4 psi regulator with satisfactory results.
I have down drafts on my coupe; if the car sits for a week without being started I have to crank it for a bit before it starts. I am considering leaving the mechanical pump in place and adding a Carter electric fuel pump with a switch to first pump fuel up to the carburetors before attempting to start, has any one tried this?
Thanks, Doug
Thanks, Doug
Polariscsl
Well-Known Member
I have an electronic controller that runs the pumps for 3 seconds when you turn the key to position 1. This primes the carbs before any attempt to start it.
Mike Goble
Well-Known Member
How do two pumps in series provide maximum volume?
If you need a little booster pump, I would use a shuttle pump with no anti-siphon valve rather than a rotating vane pump like the Carter. The best solution is to fix the actual problem with the fuel system, as it isn't a good idea to introduce fuel under pressure into your mechanical fuel pump in case the diaphragm leaks.
Polariscsl
Well-Known Member
Clearly I meant parallel! See pic!
Mike Goble
Well-Known Member
The picture doesn't show up on my computer. I apparently don't have enough of a security clearance or something.
I used to run one of those Facet pumps in my track car, and it worked very well, but my god it was noisy!
I could even hear it clattering away with my helmet on when just sitting in the car at idle.
I think what ever you end up buying will be a bit on the noisy side, it seems most of these aftermarket pumps these days are fairly rowdy, so good idea to mount outside the car under the trunk floor (maybe where the standard FI pump goes) and isolate it on rubber mounts.
I could even hear it clattering away with my helmet on when just sitting in the car at idle.
I think what ever you end up buying will be a bit on the noisy side, it seems most of these aftermarket pumps these days are fairly rowdy, so good idea to mount outside the car under the trunk floor (maybe where the standard FI pump goes) and isolate it on rubber mounts.
You can get a mech pump delete plate from lajolla ind. I deleted mech pump, e-pump runs on toggle, fills bowls, you can hear them fill. Always a welcomed and satisfying sound ;-)
Pump is mounted in trunk on rubber mounts and is audible. System is dead simple and realiable.
Pump is mounted in trunk on rubber mounts and is audible. System is dead simple and realiable.
Just wondering if you have any provision for shutting it off in the event the engine conks out or you get in an accident? Ford's have an impact cutoff switch that is available in every junkyard or on line. I also have a cutoff hooked up to my oil pressure. Stevehose has a nice setup using an electronic box that will run the pump for a few seconds before startup and switch off if the engine does not run.
Polariscsl
Well-Known Member
Believe it or not my current setup is very quiet - it is isolated and rubber mounted. You can't hear the pumps at idle, and only hear them prime before a cold start. I experimented with a single facet under the car but it was, as you say, too noisy.
Mike Goble
Well-Known Member
I use a standard VDO in-tank low pressure pump from a BMW that has the external HP pump in series. It puts out about 3# with no regulator, it's pretty quiet in the tank and spares are really easy to find. You don't have to worry about losing the prime as you would with an external pump, it has a built in screen, and it's cheap.