Why Mr Lucas?

[Lionelgee]

Hello All,

I worked out today why I had no sparks going to the spark plugs in my 2.6 litre six cylinder engine. It is because I followed logic. Apparently this stance and the wiring of the Land Rover electric fuel pump is not compatible.

When I was sorting out the ignition switch wiring I heard the electric fuel pump coming on. Since the petrol tank is empty and I am using a temporary fuel tank from a ride on mower I disconnected the wire on the ignition that I thought controlled the electric fuel pump coming on. A logical step? Well I thought so as electric fuel pumps do not like sucking air. I thought that the power to the fuel pump came via the ignition switch - to me that is logical.

I then tried to start the engine and despite the starter motor definitely winding over the engine did not start.

Having been trained in science I then followed a process of elimination. I found out that when a spark plug was taken out and held against the block there was no spark with the starter motor going. I could not easily see the distributor due to my current eye situation so I tested the coil. No spark. Bugger!

Today I used a test lamp and looked at the wiring diagram in the Green Bible again. There is meant to be power going from the ignition switch to the positive side of the coil. So I found the wire that links the ignition to the positive side of the coil and the test lamp did not light up = no sparks. I tested each of the connectors on the ignition switch and each one worked on the Ignition and ACC + Battery. I then placed the wire the schematic diagram said provided power from ignition to the coil. Not only did I have sparks to the coil again so too was the fuel pump going! Whaattt??? I checked the schematic diagram again and looked at the positive side of the coil and bugger me if there is not a dual post terminal on the positive side of the coil. The second terminal has another wire that goes directly back to the electric fuel pump!

When I had taken off the wire connector off the ignition switch to stop the fuel pump going on I had actually disconnected the power to the coil! I readily admit that I did not check the schematic drawing of the fuel pump circuit before this afternoon. Because I thought I had disconnected it at the ignition switch - through following logic.

I did a check online with the search of "how to wire up an electric fuel pump auto" and came across a hotrod site that has the wire from the ignition switch to a pressure switch via a relay to the starter wire. No contact with the coil at all. Accessed 20th of August 2014 from, Electric Fuel Pump: How to Do It Right (http://www.how-to-build-hotrods.com/electric-fuel-pump.html)

So why Mr Lucas would you wire a electric fuel pump to the positive side of the coil???? :censored: :twisted:

I actually got the engine started for a wee while. Then I noticed fuel dripping out of the bottom of the Zenith Stromberg CD 175 s - it is flooding - bugger!

At least I have sparks back to the coil and to the spark plugs again :p

Oh I have disconnected the electric fuel pump - at the coil. I will be using the Hotrod wiring circuit shown in the link to rewire the fuel pump after I get the engine running smoothly. Yes I do have spark from the ignition to the positive side of the coil now too :p

Kind Regards
Lionel

[Lotz-A-Landies]

Excuse me Lionel, you're addressing the manufacturer contemptuously with lack of respect..

The correct form of address is: His Royal Highness Joseph Lucas Prince of Darkness!

[Timj]

Hi Lionel,

The other question might actually be "Why not?". When looking for a power source that is only on when the ignition is on then it is probably not a bad place, one less wire through the firewall. I would be tempted to add a modern touch with one of the automatic cutout switches that will turn the pump off if the engine is not running and maybe an individual fuse but apart from that it doesn't matter where the power sources from.

Cheers,

TimJ.

[gromit]

Also it should be 'why Mr Land Rover'.
Lucas provided the parts but I'm not sure they would have been involved in the wiring layout.


Colin

[Lionelgee]

Hi Lionel,

The other question might actually be "Why not?". When looking for a power source that is only on when the ignition is on then it is probably not a bad place, one less wire through the firewall. I would be tempted to add a modern touch with one of the automatic cutout switches that will turn the pump off if the engine is not running and maybe an individual fuse but apart from that it doesn't matter where the power sources from.

Cheers,

TimJ.


Hello Tim,

The wire from the coil to the fuel pump siphons away sparks from the coil to the distributor to the spark plugs. It may not take much, however I like all the sparks from the coil being dedicated towards making the engine work. Oh plus there is no relay in the system and no form of turning off if there is an accident.

It is like they did a count of the posts on the ignition switch and could not add another, so they stole power from somewhere else.

The hotrod circuit also has the issue that the engine needs to have full oil pressure before it turns the fuel pump on. If the car is not used for some time it could take a lot of cranking before the oil pressure reaches the correct level to operate the fuel pump.

The options seem to be either a kill switch on the dash or a tachometric relay that are used in LPG fuelled cars.

Kind Regards
Lionel

[Lionelgee]

Also it should be 'why Mr Land Rover'.
Lucas provided the parts but I'm not sure they would have been involved in the wiring layout.


Colin

G'day Colin,

I take on board what you say. I was going to write the title as, "Why Mr Leyland" since it is a Series 3. Then I thought of the Prince of Darkness - Mr Lucas. I am sure the two talked together and conspired in their plot for engineered obsolescence somewhere along the track.

That's right wheel in the Conspiracy Theory model, when things like logic fail. Especially since it was through my own inattention to the full schematic diagram that I disconnected the circuit from the ignition to the coil in the first place anyway :angel:

Kind Regards
Lionel

[JDNSW]

Hello Tim,

The wire from the coil to the fuel pump siphons away sparks from the coil to the distributor to the spark plugs. It may not take much, however I like all the sparks from the coil being dedicated towards making the engine work.

Rubbish! Neither the ignition nor the fuel pump draw high currents, and if the wire size is adequate there is no problem whatsoever in this layout. Since the pump and the coil are on the engine side of the firewall, there is a good reason for doing it that way.

Oh plus there is no relay in the system and no form of turning off if there is an accident.

Ignition switch turns it off - as would happen if there were a relay. Adding a relay is adding another failure point for no good reason. G-sensitive switches or relays to kill electrics after an accident are something that was added to car designs many years after the Series 3 was designed, in fact, long after production of it stopped. Expecting a car designed in 1970 to 1990 design features is just plain silly.

It is like they did a count of the posts on the ignition switch and could not add another, so they stole power from somewhere else.

Using a different switch for the six (the four does not have an electric pump) would make even less sense.

The hotrod circuit also has the issue that the engine needs to have full oil pressure before it turns the fuel pump on. If the car is not used for some time it could take a lot of cranking before the oil pressure reaches the correct level to operate the fuel pump.

One of the advantages of the electric pump is that it will fill the carburettor before you even start to turn the engine - can be an important factor if the battery is not too good or it is very cold. Perhaps a case for a kill switch, but I never even thought of it in Landrovers I have owned with electric pumps.

The options seem to be either a kill switch on the dash or a tachometric relay that are used in LPG fuelled cars.

Kind Regards
Lionel

One of the contributors to the decline of UK motor manufacturing was that starting during the 1940s Lucas either drove out of business or bought all of their competitors, by producing products that were cheaper (and nastier), thus getting the contracts with the major manufacturers, so that by the 1960s manufacturers had no choice but to use their products, make them themselves (not practical except for companies like Ford and GM), or import them (not practical with the protection then used in Britain).

It is probably lost in the mists of time just how the electrical system design responsibility was shared between Lucas and Rover/Leyland, but my guess is that most of the design was by Lucas, especially since it involved a change from the generator used in Series 2a to the alternator used in Series 3 (and also in 2a six), which Rover had very limited experience of.

John

[Lionelgee]

Since the pump and the coil are on the engine side of the firewall, there is a good reason for doing it that way.

Hello John,

The electric fuel pump in the 2.6 litre is not on the same side of the firewall as the coil. The fuel pump is located very close to the fuel tank. This is in accordance with the recommendations of manufactures such as Facet electric fuel pumps. Accessed 20th August 2014 from http://www.facet-purolator.com/cube-fuel-pumps.php "mount the pump close to the fluid or fuel tank and below the liquid level".


Relays may provide a source of possible failure and they also supply a less impeded supply of current to heavy draw things like the headlights and the starter motor while only using a small current via the ignition switch itself; or their dedicated switches such as Part number 575383. I have already had to replace the indicator horn stalk because the horn burnt out the wiring when the previous owner had the vehicle. I will be fitting horn relay to protect this from happening again. It is also a case economics: pay as little as $16.85 (AUD) for a genuine Bosch relay - http://www.ebay.com.au/itm/GENUINE-BOSCH-12V-30A-SPDT-STANDARD-5-PIN-RELAY-0332209150-/141143196985?pt=AU_Car_Parts_Accessories&hash=item20dcca4539

or pay $120 (AUD) + postage for a Land Rover Series 3 Indicator Switch - http://www.ebay.com.au/itm/Land-Rover-Series-3-Indicator-Switch-Lucas-575383-Blinker-/200994105498?pt=AU_Car_Parts_Accessories&hash=item2ecc2ea89a. The same previous owner rigged up a floor mounted dimmer switch because the original circuit burnt out. I also want to fit driving lights and I will be fitting relays too.


One of the advantages of the electric pump is that it will fill the carburettor before you even start to turn the engine
The description in the hotrod link that I included previously (http://www.how-to-build-hotrods.com/electric-fuel-pump.html) states that, "The switch will stop the pump whenever the oil pressure in the engine goes away. So, whenever the engine is off, the pump will turn off automatically. This suggests that with the engine off there is no oil pressure and the fuel pump will not start. Within the example presented in the article,this unfortunately removes the advantage of an electric fuel pump wired via the ignition switch/coil.


I would prefer to be able to turn off the fuel quickly if I was in an accident or a fuel line split. Ignition switches can fail so having a full dependency on the ignition switch/coil to turn a pump off makes me uncomfortable. Hence a number of non-ignition switch dependent alternatives such as a kill switch.

You can call me silly for valuing the life of my passengers and myself. To do so I will build in as many redundancies for safety in a vehicle that I can. These are things that can be done without detracting too much from the vehicle. I also upgraded my Series 3 diesel from a single circuit to a dual circuit brake system. I upgraded from 4 cylinder to 6 cylinder sized brake shoes and backing plates. A single circuit brake system may never fail, I would still prefer to have the dual circuit system if things happen to go wrong.

Kind Regards
Lionel

[JDNSW]

Since the pump and the coil are on the engine side of the firewall, there is a good reason for doing it that way.

Hello John,

The electric fuel pump in the 2.6 litre is not on the same side of the firewall as the coil.


Depends on when the vehicle was built - suffix 'A' had the pump mounted on the firewall in the engine compartment unless I am mistaken, which may suggest why power was picked up in this area.

Relays may provide a source of possible failure and they also supply a less impeded supply of current to heavy draw things like the headlights and the starter motor while only using a small current via the ignition switch itself; ...
No arguments at all - and headlights in particular are a place where Landrovers should have introduced relays very early, and horns as well, although I must admit I have rarely heard of horns being a problem. But the fuel pump is not a high power device like any of these.

One of the advantages of the electric pump is that it will fill the carburettor before you even start to turn the engine
The description in the hotrod link that I included previously (Electric Fuel Pump: How to Do It Right (http://www.how-to-build-hotrods.com/electric-fuel-pump.html)) states that, "The switch will stop the pump whenever the oil pressure in the engine goes away. So, whenever the engine is off, the pump will turn off automatically. This suggests that with the engine off there is no oil pressure and the fuel pump will not start. Within the example presented in the article,this unfortunately removes the advantage of an electric fuel pump wired via the ignition switch/coil.


I would prefer to be able to turn off the fuel quickly if I was in an accident or a fuel line split. Ignition switches can fail so having a full dependency on the ignition switch/coil to turn a pump off makes me uncomfortable. Hence a number of non-ignition switch dependent alternatives such as a kill switch.

This is your view, but I suggest that most owners value more highly easy starting and reliability. And it is hardly fair to criticise the design of a 1960s electrical system because it does not conform to twenty-first century hotrod standards. Do you know of any other 1960s designs with this feature?

You can call me silly for valuing the life of my passengers and myself. To do so I will build in as many redundancies for safety in a vehicle that I can. These are things that can be done without detracting too much from the vehicle. I also upgraded my Series 3 diesel from a single circuit to a dual circuit brake system. I upgraded from 4 cylinder to 6 cylinder sized brake shoes and backing plates. A single circuit brake system may never fail, I would still prefer to have the dual circuit system if things happen to go wrong.

I agree entirely that all these are eminently reasonable upgrades, but I do not agree that an oil pressure operated switch on the fuel pump is in the same league as these. And I particularly disagree with criticising the original design on these grounds. Heaven knows, there are enough other things to criticise about the electrics! But go ahead and do it on your S3. As you say it will not be detrimental to it, as long as there is a switch to bypass it to aid starting.


.....


When the Landrover was originally introduced, there appears to have been a conscious effort to keep the electrics as simple as possible. I doubt this was a cost decision, but rather to simplify maintenance and repair and to increase reliability. This extended to almost no fuses!

Unfortunately, expected and mandated electrical gadgets multiplied over the years and were more or less patched on to the earlier simple electrics. By the time the Series 3 was introduced this had resulted in what was conceptually a patchwork electrical system. It should have been redesigned from scratch, but with Landrover being the only profitable part of Leyland, and treated as a cash cow, it did not happen. The 110 did get the system redesigned, although still with a number of shortcomings (still Lucas!).

John

[Lionelgee]

G'day John,

The vehicle in question was manufactured in November 1978.

When I looked through the list of results for my search "how to wire up an electric fuel pump auto" none of them incorporated the coil in their circuits. So from the results of a very quick and far from exhaustive search it seems that the Land Rover circuit for the electric fuel pump via the coil is somewhat unique.

It is also the realisation that my own misguided efforts of stopping the operation of the fuel pump at the ignition had directly caused me two weeks of trying to get the vehicle to start. I found this to be just a little bit frustrating. Especially, because it was impossible for the coil to function because I had disconnected the ignition to coil wire. The finger points squarely towards myself in this matter. I should have had a closer look at the schematic drawing and found out where the electric fuel pump drew its power from. I did not do this because I thought I had eliminated power to the fuel pump. In the process I had also eliminated power to the coil - distributor and spark plugs!


Kind Regards
Lionel

[Timj]

Hi Lionel,

When I put an electric fuel pump on my Series 3 I put a cutout switch which I believe is the type you mentioned above as a tach based one. They are cheap and easy insurance, if the engine is not running then it cuts the pump. I would not be as worried about the power source (provided the wiring is adequate for the current carried and is fused) as I would be about cutting the petrol in the event of an accident. If the vehicle is on it's side or upside down then petrol comes out of a carbie through the vents no matter what you do so if you can limit that to just the contents of the float bowl then it is a good thing.

You can get a much better result from fuel injecting though as no petrol flows that you don't want, no matter what the angle, and the pump cuts out automatically when the engine stops :).

Cheers,

Tim.

[PhilipA]

As I said to my mate who just put one of those oil pressure switches in a Marina classic racer!!!, Why not just put an inertia switch from an RRC /Disco 1/Disco 2 in the circuit?
Then you get pumping ignition on , just like a Range Rover Classic.
Regards Philip A

[Timj]

Hi Phillip,

It is not an oil pressure switch, it is an electronic switch which runs off the coil so effectively a tacho output, no coil firing = no fuel pump. It has a 3 second priming pulse when first turned on then starts full time when the engine starts running. It assumes that the engine will stop running when turned over or in an accident so perhaps one of the inertia switches would be better.

Cheers,

Tim.

[C00P]

Hi Folks,
You chaps seem to know what you are talking about when it comes to electric fuel pumps.
My Series III has an auxiliary tank under the passenger seat plumbed through a change-over tap located immediately behind the center seat.
All was well until a recent trip where I emptied the main tank and was running home on the last of the auxiliary tank (still had about 10 litres in it). The engine began to hesitate and then intermittently die as I was ascending the last hill on the freeway before the exit to the shed where the Series is stored when not in use. It felt like fuel starvation. I was able to encourage the beastie over the crest by lifting off and working back through the gears. Once the load came off (flat ground) we motored along happily to the shed.
The auxiliary tank sits over the top of the exhaust pipe with only a shield protecting it from the heat. So the fuel in that tank does get a bit warmer than in the main tank. Plus, it's a fairly long run from the auxiliary tank to the carby. I wondered if the low level of the tank put too much low pressure on the fuel line causing vapourisation, or maybe the mechanical fuel pump couldn't lift that far.
So maybe I should put a fuel pump near the auxiliary tank to keep the pressure up in the system when the auxiliary tank is being used.
The machine is running fine now that the tanks have been refilled.
How would you set up such a fuel pump? I figured a switch on the dash so that I could turn it on only when needed.
Any suggestions?
Cheers

Coop