Fuel pump problems?

[67Fox]

I have a problem starting the car. (I know it's a common problem, and have read a lot on hear about it but....)
So i have not run the car for a few months. (been away for work etc...)

I was free this weekend so i thought I would change the spark plugs clean the stepper motor and take her for a spin.
So I changed the spark plugs (what a pain in the arse job that is!!! but that's another story )
Cleaned the stepper motor but that was really clean, so easy job. ( the stepper motor was very lose in the plenum though, two fingers and it was lose!)
Checked the spark plug leads were correctly placed on the correct spark plugs, Twice!!

So here goes. Started the car , OK.........15 sec or so later the car stops running. So I try to start her again and the engine turns over and over but does not catch.

So I check again the spark plug leads making sure all where correctly on the spark plugs, try again nothing. So I removed the 8x extenders and tried again. Nothing
So then sat in the car and just turned the ignition key until the ignition was on. (Red light) And listened. nothing! no humm from the petrol pump?? Is this normal?
When turning the key and waiting 3s or so secs I hear a click. but no humm. Is this normal?
I can't remember when the car ran fine if the petrol pump primed before I started her last time. Typical, i don't remember this.

I did jack the car up and gently tapped the pump to see if that was it but nothing.

I know it could be the immobolisor, but I believe that this has been bypassed by the previuos owner. As the car has started before with the car locked!!
I have also tried to lock /unlock / lock / unlock /... but also nothing

Any suggestions would be welcome.

[QBee]

You always hear the fuel pump priming. No pump prime, no run.
I have also noticed recently that I can hear the fuel pump when stopped at traffic lights.

Immobiliser is the normal reason for no pump prime.
Lead off the pump is another possible.
Stuck relay.
No fuel in tank.
Inertia switch......but you have to jolt the car pretty hard to activate that in my experience (once in 30,000 miles, entering a gravel trap sideways.)

Of course it won't start without a spark either.....king lead, ignition amplifier,

[wuckfitracing]

You could take the 2 wires off the fuel pump and put a meter on it to check for 12 Volts whilst switching the ignition on..

[N7GTX]

If you haven't got a meter, buy a type 501 sidelight capless bulb (Halfords, motor shops etc) and unravel the two wires. Take off the fuel pump wires and push one wire of the bulb into each wire and do as said above. Remember the pump only runs for around 3 seconds with the ignition on so best get someone to switch on for you unless you have 10 foot arms....
If there is power the bulb will light up. Not accurate but at least it lets you know if there is power.

[67Fox]

QBee said:

You always hear the fuel pump priming. No pump prime, no run.
I have also noticed recently that I can hear the fuel pump when stopped at traffic lights.

Immobiliser is the normal reason for no pump prime.
Lead off the pump is another possible.
Stuck relay.
No fuel in tank.
Inertia switch......but you have to jolt the car pretty hard to activate that in my experience (once in 30,000 miles, entering a gravel trap sideways.)

Of course it won't start without a spark either.....king lead, ignition amplifier,

OK QBee.
Were would I find the (maybe stuck) Fuel pump relay please. Foot well? and if so which colour?
Fuel is in the tank as I filled it up not long ago.
Inertia switch, possible..... Were would I find that little gem then?

[SMB]

67Fox said:

OK QBee.
Were would I find the (maybe stuck) Fuel pump relay please. Foot well? and if so which colour?
Fuel is in the tank as I filled it up not long ago.
Inertia switch, possible..... Were would I find that little gem then?

I had exactly these symptoms a few years back, started , ran for 15 seconds then stopped. Normal failure pattern is just a simple no start, The relays are in the footwell, normally silver with an orange strip over the top. Should be 2 one for ecu one for the fuel pump, normal relays with the same pin out can be used as a get you going but replace with the correct ones Asap or the battery will drain.

[pete275]

Fuel pump relay is in the passenger footwell, I think its the one in the blue socket

Inertia switch is under the passenger side of the dash, if you undo the 2 screws holding the glove "pouch" its hiding in there

[SMB]

67Fox said:

OK QBee.
Were would I find the (maybe stuck) Fuel pump relay please. Foot well? and if so which colour?
Fuel is in the tank as I filled it up not long ago.
Inertia switch, possible..... Were would I find that little gem then?

I had exactly these symptoms a few years back, started , ran for 15 seconds then stopped. Normal failure pattern is just a simple no start, The relays are in the footwell, normally silver with an orange strip over the top. Should be 2 one for ecu one for the fuel pump, normal relays with the same pin out can be used as a get you going but replace with the correct ones Asap or the battery will drain.

[QBee]

SMB said:

67Fox said:

OK QBee.
Were would I find the (maybe stuck) Fuel pump relay please. Foot well? and if so which colour?
Fuel is in the tank as I filled it up not long ago.
Inertia switch, possible..... Were would I find that little gem then?

I had exactly these symptoms a few years back, started , ran for 15 seconds then stopped. Normal failure pattern is just a simple no start, The relays are in the footwell, normally silver with an orange strip over the top. Should be 2 one for ecu one for the fuel pump, normal relays with the same pin out can be used as a get you going but replace with the correct ones Asap or the battery will drain.

Would that be because it is using the fuel left in the fuel rail? Interested.....

The inertia switch is under the glove pouch as stated. Undo the screws, drop the pouch down and feel around the hole - you will feel a rubber covered button, mine was up and right IIRC. Press to reset. I doubt it is that, but worth a check.

[Oldred_V8S]

SMB said:

I had exactly these symptoms a few years back, started , ran for 15 seconds then stopped. Normal failure pattern is just a simple no start, The relays are in the footwell, normally silver with an orange strip over the top. Should be 2 one for ecu one for the fuel pump, normal relays with the same pin out can be used as a get you going but replace with the correct ones Asap or the battery will drain.

And don't switch them over, they are interlinked.

[davep]

Oldred_V8S said:

And don't switch them over, they are interlinked.

How are the Fuel Pump and Main Voltage relays interlinked? They are used in two different circuits and when ignition On is sensed separately controlled from ECU pin 16 and pin 12, respectively. If one of the relays is faulty then the respective +12 Vdc supplies are not realised, swapping relays simply means the Fuel Pump supplies are made and not Main Voltage, or vice versa.

[Oldred_V8S]

davep said:

Oldred_V8S said:

And don't switch them over, they are interlinked.

How are the Fuel Pump and Main Voltage relays interlinked? They are used in two different circuits and when ignition On is sensed separately controlled from ECU pin 16 and pin 12, respectively. If one of the relays is faulty then the respective +12 Vdc supplies are not realised, swapping relays simply means the Fuel Pump supplies are made and not Main Voltage, or vice versa.

The switches of the relays are connected, any failure at either one of these would stop the pump running. Connection 87 of the fuel pump relay supplies the pump. It gets its supply through the switch contacts of the FP relay, which in turn comes through the switched circuit of the main relay. Swapping a faulty FP relay with the main relay will give the same symptom, a non running pump. Other symptoms may occur, but someone listening for the pump to prime may not notice these and assume the relays were good.

[davep]

Oldred_V8S said:

The switches of the relays are connected, any failure at either one of these would stop the pump running. Connection 87 of the fuel pump relay supplies the pump. It gets its supply through the switch contacts of the FP relay, which in turn comes through the switched circuit of the main relay. Swapping a faulty FP relay with the main relay will give the same symptom, a non running pump. Other symptoms may occur, but someone listening for the pump to prime may not notice these and assume the relays were good.

From the diagram: +12Vdc battery voltage (N) is applied to the Fuel Pump Relay (COM pin 30), the Main Relay (COM pin 30 and Coil pin 86), and ECU +ve supply (pin 15). When ignition is switched On, the ECU, via pin 12, earths the Main Relay (Coil pin 85, Blue/Red), and the relay is energised feeding +12Vdc (two Brown/Orange) to the injector circuits, the AFM, and ECU pin 2, where Main Voltage is monitored for injection pulse width purposes. Also +12Vdc (White/Slate) is applied to the Fuel Pump Relay (Coil pin 86) and to ECU ignition sense (pin 19). The ECU, via pin 16, now earths the Fuel Pump Relay (Coil pin 85, Blue/ Purple), the relay is energised feeding +12Vdc (White/Orange) to the Lambda sensors, the fuel pump (White/ Purple) via a fuse and the Inertia Switch, and the Purge Control Valve (if fitted).

But how does the Fuel Pump relay contact (pin 30) get its supply from the Main Relay switched circuits?

[Oldred_V8S]

davep said:

But how does the Fuel Pump relay contact (pin 30) get its supply from the Main Relay switched circuits?

Pin 2 ECU - Brown/Orange to pin 87A of main relay supplies +12v to the fuel injectors (which are switched by grounding them), the AFM and the fuel pump relay via the main relay switched contacts.

Once the main relay is activated and closes its contacts, +12v is output from the 30/51 contact to the fuel pump relay contact 30/51, (activated by the ECU via pins 16+19) to give +12v fuel pump and Lamda's.

[67Fox]

davep said:

From the diagram: +12Vdc battery voltage (N) is applied to the Fuel Pump Relay (COM pin 30), the Main Relay (COM pin 30 and Coil pin 86), and ECU +ve supply (pin 15). When ignition is switched On, the ECU, via pin 12, earths the Main Relay (Coil pin 85, Blue/Red), and the relay is energised feeding +12Vdc (two Brown/Orange) to the injector circuits, the AFM, and ECU pin 2, where Main Voltage is monitored for injection pulse width purposes. Also +12Vdc (White/Slate) is applied to the Fuel Pump Relay (Coil pin 86) and to ECU ignition sense (pin 19). The ECU, via pin 16, now earths the Fuel Pump Relay (Coil pin 85, Blue/ Purple), the relay is energised feeding +12Vdc (White/Orange) to the Lambda sensors, the fuel pump (White/ Purple) via a fuse and the Inertia Switch, and the Purge Control Valve (if fitted).

But how does the Fuel Pump relay contact (pin 30) get its supply from the Main Relay switched circuits?

Davep. Thanks for the feedback, the fuse you mentioned that is I assume in the footwell, but what size fuse is it? and where on the fuse board would I find that?
I have a 1993 430. as my profile will show

To all of you, a lot of diagnostic information. You really know your stuff. It's great to have guys like you on the forum.

[Aussie John]

The fuel pump fuse on my 94 Griff is loose in the wiring near the pump relay and not on the board; I think it was a 20A. Just run a 12v feed from the battery direct to the pump, if it doesn't run then it's the pump [ or a bad earth on the pump.]

[davep]

Oldred_V8S said:

Pin 2 ECU - Brown/Orange to pin 87A of main relay supplies +12v to the fuel injectors (which are switched by grounding them), the AFM and the fuel pump relay via the main relay switched contacts.

Once the main relay is activated and closes its contacts, +12v is output from the 30/51 contact to the fuel pump relay contact 30/51, (activated by the ECU via pins 16+19) to give +12v fuel pump and Lamda's.

Sorry to keep banging on, but it looks to me like the diagram is wrong for interlinking to work since 30/51 from the Main Relay is not an output. It could be that our 14CUX TVRs are wired as follows: A +12V battery voltage is not applied to 30/51 of the Fuel Pump relay, instead it gets a switched +12V from pin 87 of the Main Relay. I'll check this later to verify.

[Oldred_V8S]

davep said:

Oldred_V8S said:

Pin 2 ECU - Brown/Orange to pin 87A of main relay supplies +12v to the fuel injectors (which are switched by grounding them), the AFM and the fuel pump relay via the main relay switched contacts.

Once the main relay is activated and closes its contacts, +12v is output from the 30/51 contact to the fuel pump relay contact 30/51, (activated by the ECU via pins 16+19) to give +12v fuel pump and Lamda's.

Sorry to keep banging on, but it looks to me like the diagram is wrong for interlinking to work since 30/51 from the Main Relay is not an output. It could be that our 14CUX TVRs are wired as follows: A +12V battery voltage is not applied to 30/51 of the Fuel Pump relay, instead it gets a switched +12V from pin 87 of the Main Relay. I'll check this later to verify.

Interesting. It does tie in with how my car is wired; I checked the pinouts when I too ran into issues with the FP relay and swapped it with the main relay (in my defence, it was in the early days of ownership).

I suspect it is wired backwards 87>30 rather than the conventional 30>87 as Land Rover were using relays with two connections at pin 87, one for the FP and one for the Lambda's.

The bottom line is that the relays are serially linked through the switched contacts, regardless of how they are wired, again at least they are on my car, but that's TVR for you, yours may be totally different again. interested to hear what you find.

Edited by Oldred_V8S on Thursday 5th November 09:52

[SMB]

QBee said:

Would that be because it is using the fuel left in the fuel rail? Interested.....

at the time I assumed that the relay triggered initially to prime the pressure in the fuel rail before the relay failed to connect, this allowed the car to start but it then stalled and failed to restart. the ecu and fuel relay both need to work ( wired in series in some way, logical as the car primes when the ecu receives power) for the car to start, so as was said just swapping them round doesn't fix the failure.

[blitzracing]

You mention you here a click after a few seconds- this tells you a lot. It means the main relay is working- it also means the fuel pump relay is closing at the same time as the main relay, with power from the main relay. This means either the fuel pump relay has faulty contacts or something outside the ECU loom like immobiliser, trip switch or jammed pump.