02GF74
|
| posted on 7/4/06 at 11:55 AM |
|
|
intelligent fuel pump?
In the land rover I have a facet fuel pump that is powered all the time when the igntion is on.
Iam wondering whether an electrical pump exists that pumps petrol according to the demand of the engine?
A simple circuit driven off the igntion coil so the pump pumps more at higher rpm would be easy to tonk up; a more sophisticated version would use
throttle position to increase the pumping according to engine loading.
the advantages are quieter operation, longevity and less power drawn (ok, the last one is miniaml but it all counts!)
|
|
|
|
|
muzchap
|
| posted on 7/4/06 at 12:03 PM |
|
|
but if it goes wrong... then it's a dead pump! 
Quiter operation - if ya can hear the fuel pump over the zorst - fair play
Your pump - give it a go ;-)
and more importantly
GOOD LUCK (if it works - I'll have one  )
------------------------------------
If you believe you're not crazy, whilst everybody is telling you, you are - then they are definitely wrong!
------------------------------------
|
|
|
greggors84
|
| posted on 7/4/06 at 12:24 PM |
|
|
You would have to make it so it pumped more or less depending on engine speed/throttle position instead of just coming on or off.
Not sure if you can get a variable pump. If you can then im a system has been designed as otherwise variable pumps would exist (if they do!)
Chris
The Magnificent 7!
|
|
|
oliwb
|
| posted on 7/4/06 at 01:41 PM |
|
|
What about a motorbike fuel pump such as one from a goldwing?? They pump to a specific pressure and then cut out like an SU pump....obviously the less
the engine is revving the less demand for fuel so the pump reaches its threshold pressure sooner and cuts out, then when your ragging it its on all
the time....also removes the need for a regulator and prevents overfilling of the fuel bowl and subsequent flooding.....Clever stuff! Oli.
If your not living life on the edge you're taking up too much room!
|
|
|
procomp
|
| posted on 7/4/06 at 02:02 PM |
|
|
Hi they do. Facet interupter type one.
cheers matt
|
|
|
JAG
|
| posted on 7/4/06 at 02:07 PM |
|
|
Isn't this what more recent fuel injected petrol engines do - that's why they don't have a fuel pressure regulator or fuel return
line to the fuel tank.
The pump supplies just enough fuel at just the right pressure hence all fuel delivered to the engine is consumed whilst keeping the pressure with
certain tolerances.
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
|
|
|
Peteff
|
| posted on 7/4/06 at 02:22 PM |
|
|
Old SU pumps worked on demand. when there's no pressure they pump, then they cut out till it drops again, nothing complicated though just
pressure activated.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
|
|
|
02GF74
|
| posted on 7/4/06 at 03:06 PM |
|
|
quote:
Originally posted by procomp
Hi they do. Facet interupter type one.
cheers matt
ah, I forgot one important bit of info., it is an open system so fuel is continuously pumped back from the carbs into the tank (stops air locks
apparently) hence this would not work for me.
|
|
|
MikeRJ
|
| posted on 7/4/06 at 03:25 PM |
|
|
The fuel pump in my MR2 turbo switches tro a low power mode at idle, though this is controlled by the ECU. It just switches a relay which puts a big
power resistor in series with the pump. Locost method would be a microswitch on the throttle pedal I guess...
|
|
|
silex
|
| posted on 7/4/06 at 04:57 PM |
|
|
One of the electronics wizzez on the site might know better, but using a potentiometer on the throttle pedal into a 555 timer or similar you should be
able to create a PWM (Pulse Width Modulated) signal to the pump. This would act like a variable speed controller to the electric pump (I think).
You would need to put in a high power transistor or FET in the circuit to handle the current of the pump but I think it would work.
Murphy's 2 laws
1. If it can go wrong it will
2. In case of emergency - refer to rule 1.
|
|
|
Johnmor
|
| posted on 7/4/06 at 04:59 PM |
|
|
Fuel Pump
Alfa engine ECU,s only switch power to the pump when the engine is turning, and will not supplly power only if the ignition is on, prevents pump wear
and means that if you have a accident the pump is switched of if the engine stops.
Means you dont need an impact cut off switch.
Detection is from the ignition timing pickup and switched through a relay.
Dont know if this is much help.
|
|
|
RazMan
|
| posted on 7/4/06 at 05:21 PM |
|
|
quote:
Originally posted by Johnmor
Alfa engine ECU,s only switch power to the pump when the engine is turning, and will not supplly power only if the ignition is on,
That is how my MBE ecu trigger my Landy fuel pump - Ignition on (give a 2 second prime) Engine start (starts pump) Engine stall (stops pump)
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
|
|
|
the_fbi
|
| posted on 7/4/06 at 05:52 PM |
|
|
quote:
Originally posted by RazMan
quote:
Originally posted by Johnmor
Alfa engine ECU,s only switch power to the pump when the engine is turning, and will not supplly power only if the ignition is on,
That is how my MBE ecu trigger my Landy fuel pump - Ignition on (give a 2 second prime) Engine start (starts pump) Engine stall (stops pump)
I believe thats the same for XE's too, unless there is a crank signal the pump doesn't operate.
|
|
|
MikeRJ
|
| posted on 7/4/06 at 05:53 PM |
|
|
quote:
Originally posted by Johnmor
Alfa engine ECU,s only switch power to the pump when the engine is turning, and will not supplly power only if the ignition is on, prevents pump wear
and means that if you have a accident the pump is switched of if the engine stops.
Most fuel injected cars do this. They often allow the pump to run for a second or two when you switch the igntion on to build up pressure in the fuel
rail ready to start the engine.
Silex, you could do that but I'm not convinced the extra complexity is worth it on a 7. If the fuel pump is particularly noisy then it might be
worth slowing it down at idle, but unless you have a particulary quiet 7 when as soon as you start driving the engine and wind noise will drown out
most things.
By the way, I suspect the only fuel pumps that can be successfully slowed down this way are rotary based ones that take a continuous current ( i.e.
with a motor) rather than the oscillating plunger type that takes current in short pulses.
|
|
|
Syd Bridge
|
| posted on 7/4/06 at 06:16 PM |
|
|
I would think that you are correct Mike, regarding the rotary vs pulsed.
Although this discussion is somewhat academic, a pulsed pump could be controlled with a 555 firing a transistor in the pump feed. If you put a
variable resistor in the timing side of the 555, the pulse frequency could be varied, ie slow to fast. A pot on the throttle, as in an efi setup may
be able to do it.
Cheers,
Syd.
|
|
|
