fuel pump starts upon battery connection

B

billoddie

Active Member
Hi guys.
In the process of getting the old v8 to burst into life.
I was going to re route the electric fuel pump, but in the interest of simply getting the car to go, I have refitted it back to where the previous owner had it on the front inner right wing, in the engine bay.
The last owner had begun to move it from this position as apparently it was getting vapor lock.
I am not entirely certain how to go about this, so I have put it back to the original position, and will sneak it down to a nearby auto elec for some advice.
Which brings me to the current challenge.
I reconnected everything to where it previously was. (I think)
The power for the pump comes from what appears to be a wire that is tapped into the loom, and the negative is earthed to the inner front wing.
When i connect he battery, the pump chatters into life and successfully begins pumping fuel.
However, as you would know, I dont want it to QUITE do this just yet!!
What would be making it pump now...upon powering up the battery, as opposed to when it should do when the ignition is turned on?
Any advice on a more suitable position and how to retain the reserve line would be much appreciated.
I have looked at other posts regarding this, but they haven't quite answered it.
the pump is a "Facet cube" i think.
 
Sounds like the pump has been wired to a permanent live. That's not recommended, obviously!

I think one suggestion put forward here is to give a "live" feed to the fuel pump from the oil pressure light wire (not the oil pressure gauge!) that connects to the oil pressure switch under the bonnet.

The reason here being that 1) the oil light is fed via the ignition switch, and more importantly 2) if the car is involved in a crash, the engine will likely stop and so the oil pressure will drop, the oil pressure switch will earth, activate the oil light and cut the power to the pump.

I hope the good people (and Harvey too... :p) will clarify/correct what I'm saying here!
 
If the pump is wired so it only runs when the oil light is out, then you won't be able to get to start, as the oil light will be on when you try to turn it over. I don't think the way the oil light is wired is suitable anyway. Normally, the wiring goes from an ignition live, through the bulb and down to the switch on the engine, which then earths it when there's no pressure. If you take the feed from the wire to the switch in the engine bay, then you'll be putting the full current load of the fuel pump through the oil pressure light. The light will be on all the time, all be it at a reduced brightness, and the pump will run slowly as the pump and light are now wired in series. Best bet is to get a V8 wiring diagram and rewire it as Rover intended.

Tom
 
Only problem is I dont know if this vehicle originally had a electric fuel pump, or mechanical.
It is Aust car, with after market air (that looks factory). I cant see any evidence of an electric fuel pump previously mounted at the rear, yet weren't all cars with air supposed to have an electric pump?
Anyways it cant be that hard because the previous owner ran it for several years with the pump where it presently is. (Obviously I have erred in the wiring somewhere.)
That said, i dont think the present arrangement is ideal.
My understanding is the pump should be body mounted at the rear of the vehicle (ideally within 12 inches of the fuel tank). And should have a pressure regulator as well. However, it seems then that the reserve line is then lost.
Anyways, I will have a chat to Gerry (the guy who had it) and see where i went wrong.
Anymore ideas much appreciated, and thanks for all your help so far.
Wish I was a bit more skilled up, but i suppose its just a matter of keeping at it.
 
Tom W said:
If the pump is wired so it only runs when the oil light is out, then you won't be able to get to start, as the oil light will be on when you try to turn it over. I don't think the way the oil light is wired is suitable anyway. Normally, the wiring goes from an ignition live, through the bulb and down to the switch on the engine, which then earths it when there's no pressure. If you take the feed from the wire to the switch in the engine bay, then you'll be putting the full current load of the fuel pump through the oil pressure light. The light will be on all the time, all be it at a reduced brightness, and the pump will run slowly as the pump and light are now wired in series. Best bet is to get a V8 wiring diagram and rewire it as Rover intended.

Tom
Click to expand...

But the full load current to the electronic pump (It's a facet cube, isn't it?) isn't enough (or so I'm told!) to fire the bulb. The bulb resistance is much less than the effective pump resistance.

I see your point about the pump not working when the light is on:-

This is from http://www.classicroverforum.com/viewtopic.php?f=5&t=2650&hilit=facet+oil
harveyp6 said:
The best way to wire the pump is through the oil switch, and also take a supply from the starter so as the engine cranks the pump works. Then when the engine starts and the supply from the starter stops, the one from the oil switch takes over.
Click to expand...

The only problem I see there is that by taking a supply from the starter, there will be full battery volts being shorted across the oil pressure switch when starting. One way to combat that is to have a relay system (the supply to the pump being disconnected from the oil light and connected to the solenoid control wire (or maybe even the ballast bypass) with the engine turning over on the starter, when started and the starter is no longer turning, the relay releases and reconnects the pump feed to the oil light wire)

It's not an ideal situation, it involves bringing more components which can potentially fail

It's certainly recommended to have some form of "kill switch" to shut off the pump on an accident; you don't want petrol potentially being continually pumped when it's likely fuel lines may have been comprised/damaged
 
darth sidious said:
This is from http://www.classicroverforum.com/viewtopic.php?f=5&t=2650&hilit=facet+oil
harveyp6 said:
The best way to wire the pump is through the oil switch, and also take a supply from the starter so as the engine cranks the pump works. Then when the engine starts and the supply from the starter stops, the one from the oil switch takes over.
Click to expand...

The only problem I see there is that by taking a supply from the starter, there will be full battery volts being shorted across the oil pressure switch when starting. One way to combat that is to have a relay system (the supply to the pump being disconnected from the oil light and connected to the solenoid control wire (or maybe even the ballast bypass) with the engine turning over on the starter, when started and the starter is no longer turning, the relay releases and reconnects the pump feed to the oil light wire)

It's not an ideal situation, it involves bringing more components which can potentially fail

It's certainly recommended to have some form of "kill switch" to shut off the pump on an accident; you don't want petrol potentially being continually pumped when it's likely fuel lines may have been comprised/damaged
Click to expand...

You misinterpret what I wrote. You fit a three pin oil switch, one pin is for the oil light, the other two are a switch for the ignition controlled fuel pump supply (which it is designed for) so when there's no oil pressure there's no supply to the pump. If you were worried about the pump running directly through the oil switch, just use the oil switch to power up a relay with an ignition controlled supply. Then you take another supply from the starter motor (the one that would be used to give 12v to the coil on a ballasted system) to the pump so that when you operate the starter but don't have oil pressure yet you get fuel pumped up. You can also add an inertia switch into the oil switched system to give even more peace of mind. I can't see any problems.
 
Oh my, the great and wise one has spoken! *bows* :D

Oh, I apologise that I misinterpreted what you meant. :oops:

The three-pin oil switch is a good solution (I'm assuming one pin goes to earth when the oil pressure is low, the other two pins form a open connection when the pressure is low but close when the pressure is high)?

What I had thought you meant was that the supply to the starter command wire (or coil ballast-bypass) would also be connected to the live supply of the pump while that was still connected to the oil switch (which of course is earthed while the pressure is low) That would probably weld the oil switch connections shut! :-S

A relay is a good idea, I just meant that the down side is that more components = more failure points = potentially more reliability problems.

I don't have a real P6, but there's one in my mind that's continually getting the upgrades mentioned in this site. Hopefully when I do get one, I'll have a clear set of plans as to what to do!
 
Hi, this set up was fitted to SD1,s which was all very well until the engine got a bit
tired and was waiting at traffic lights( especially automatics) with a low tickover
and the oil light used to flicker, which would kill the pump and the engine would
stall just as you went to pull away. The cure was an engine rebuild but customers
wouldn't wear that and thought we were turning them over. So we ended up having
to bridge the relay out and they went off rejoicing!

So! far simpler to just run a white wire from the back of the Ignition switch.

Colin
 
My Facet pump takes its supply from after fuse 19-20, which is the fuse for the instrument gauges, stop lamps, reverse lamps and flashers, with the pump running it's own dedicated fuse. Turn the ignition to position two prior to starting the engine and I can then switch the pump on if so desired or leave it off. My engine retains the mechanical pump and I run the Facet in series with it.

Ron.
 
colnerov said:
Hi, this set up was fitted to SD1,s which was all very well until the engine got a bit
tired and was waiting at traffic lights( especially automatics) with a low tickover
and the oil light used to flicker, which would kill the pump and the engine would
stall just as you went to pull away. The cure was an engine rebuild Colin
Click to expand...

I know what you mean, but the cure is hardly a rebuild, rather a pleasant lie down for a couple of hours while you replace the ends and mains, a bit more awkward on an SD1 with the crossmember in the way admittedly, but (nearly) a doddle on a P6B, and if you used the standard P6 oil light switch for the light on a 4 pot, and the SD1 switch for the pump as well it would never have any problems.
 
i have my electric pump at the front inner wing but have moved the fuel line works very well i have wired mine to the ignition switch so once the ignition comes on it starts but also but a switch between the pump and the ignition switch so i can turn him on and off when i want and if anything did go wrong i can cut the power straight off
 
garethp6 said:
i have my electric pump at the front inner wing but have moved the fuel line works very well i have wired mine to the ignition switch so once the ignition comes on it starts but also but a switch between the pump and the ignition switch so i can turn him on and off when i want and if anything did go wrong i can cut the power straight off
Click to expand...

The pump on my E-type runs as long as the ignition is running.. but when I replace the pump, I'm thinking of wiring in a manual cut-off switch just in case I do have a shunt - which with an E-type on a motorway is looking increasingly likely as the bloody truck drivers can't seem to see me that low down!!!
 
chrisw said:
.. but when I replace the pump, I'm thinking of wiring in a manual cut-off switch just in case I do have a shunt - which with an E-type on a motorway is looking increasingly likely as the bloody truck drivers can't seem to see me that low down!!!
Click to expand...

The pessimist in me says that should you ever have a shunt you may not be in the position to actually switch it off yourself. Better to run an inertia switch to save you actually having to do it.
 
harveyp6 said:
chrisw said:
.. but when I replace the pump, I'm thinking of wiring in a manual cut-off switch just in case I do have a shunt - which with an E-type on a motorway is looking increasingly likely as the bloody truck drivers can't seem to see me that low down!!!
Click to expand...

The pessimist in me says that should you ever have a shunt you may not be in the position to actually switch it off yourself. Better to run an inertia switch to save you actually having to do it.
Click to expand...

Isn't the ignition switch enough?
It does the same job unless you get clever like Harvey suggests and upgrade to an automatic inertia :|

Anyway, what are lorries doing in the fast lane? :?
 
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