Jaguar XJ6 Series 2 Won't Start
On a Series 2 the fuel pumps should tick as soon as the key is on, before you crank. If they stay silent, or run only while the key is held in Start, the fault is in the pump feed — the relay, the ignition switch or the pump's own contacts. If it won't turn over, I'd go to the starter relay, the earths and the starter itself; if it cranks with fuel, to the spark and the cold-start device.
How bad is it · Garage, carefully
Stranded rather than unsafe
Bridging the starter solenoid or a relay cranks the engine with nothing to stop it, so make sure the car is in Park or Neutral with the handbrake on. Keep starting fluid to short bursts — a little proves the point.
Which one applies to yours depends on your symptoms, your model year and what has already been done to it.
Likely causes, most common first
Read the check cost before the odds: a free check that rules a cause out beats a likely guess that costs money.
Fuel pumps that run only in Start: the pump relay and the ignition switch
The pumps get a feed while cranking and another once the key is back in Run. Dirty pump relay contacts, or an ignition lock too stiff to spring back from Start, kill the Run feed, so the engine runs on what's in the float bowls and dies. Some cars also have an inhibit switch under the carburettors, worked by oil pressure, that cuts the pumps.
Starts after a long crank, runs half a minute or so once you let the key go, then stops. The pumps tick in Start and fall silent in Run.
Key on, engine off: the pumps should run and fill the carburettors. If they run only in Start, look for a pump feed taken from the starter relay instead of the ignition, then clean the pump relay contacts. Check the inhibit switch on the block and its wire, or bridge it as a test. Feel whether the key springs back cleanly from Start.
Clean the pump relay contacts and work white grease into a stiff ignition lock, so it returns from Start to Run. A worn barrel contact unit or a leaking starter relay can also leave the starter partly engaged — renew them if they are.
An SU fuel pump that is silent with 12 V at it: its contact points and earth
The SU pump is switched by mechanical contact points inside its end cap, not by electronics. Dirty or bent points stop the pump even though the feed is fine, and a poor earth does the same. It often starts as stalling on the move and restarting after a rest, before it refuses to start at all.
Ignition on and the pump says nothing; a test lamp on its positive terminal lights. It runs again for a while after a tap or a rest.
Put a test lamp between the pump positive terminal and earth with the ignition on. Lit and still no tick means the pump or its earth. Check the earth lead has its washers and a clean contact. Drain a little fuel into a jar to rule out dirt, and note which tank is in use.
Take off the end cap, clean and flatten the points with fine abrasive paper and set them square, then fit the earth with proper washers. Bench-test the pump on a 12 V supply before refitting. Carry a spare set of points.
A whirr and a click but no crank: a burnt-out starter
When the starter spins without turning the engine, or just clicks, either the drive isn't meeting the flywheel or the motor itself is done. If bridging the relay with 12 V gives the same whirr and click, the relay and key are cleared and the starter is the suspect.
A whirr and a click from under the car, battery healthy; a tap on the starter and a jump start change nothing.
Bypass the starter relay with a fused 12 V lead. Same whirr and click: the starter has to come out. On the bench, check whether the drive engages and the motor turns under load.
Fit a good-quality replacement starter — a cheap unit is what burnt out. Clean the pinion while it's out.
Nothing at the solenoid: the starter relay, the inhibit switch and the earths
The key doesn't feed the solenoid directly: it goes through a starter relay on the bulkhead, and the relay's earth runs through the gearbox start inhibit switch. A bad earth anywhere in the circuit defeats even a jump start.
Key to Start and nothing happens at the solenoid, yet bridging the solenoid to battery positive cranks the engine.
Key to Start and listen for the starter relay on the bulkhead: it should click. Wiggle the selector in Park, then earth the black/green wire to bypass the inhibit switch. Test lamp on white/yellow at the relay with the key at Start — no light means the ignition switch. Bridge brown to white/red to test the relay itself. Then fit a heavy earth cable from the inner wing to the engine and try again.
Worth trying: a new starter relay, a cleaned or adjusted inhibit switch, or an extra earth cable from the body to the engine.
Cranks with no spark: the coil feed, the ballast resistor or the electronic igniter
On a points car the coil is fed through a ballast resistor, which is bypassed from the starter relay while cranking. On a car converted to an aftermarket electronic igniter, wrong wiring can burn the igniter out, and then the white/black wire at the coil goes dead. A thin yellow spark that fades as the engine gets hot points to a heat-sensitive part.
Turns over well, no spark at a spare plug; no 12 V on the white/black wire to the coil, or a weak yellow spark, worst on a hot restart.
Hold a spare plug against the head and crank. With the ignition on, the white/black wire should show 12 V. A test lamp from coil negative to earth should light, then dim and flicker while cranking — if it doesn't, the igniter is dead. Clip the spark tester to a good earth, not a cam cover nut. Trace the ballast resistor and its feed for power before buying parts.
Worth trying: a correctly wired replacement igniter is enough — the distributor can stay. Renew an oily, smoking ballast resistor.
Carburettor cars that won't start cold: the AED
The AED is the automatic cold-start device on the HIF carburettors: it richens the mixture and lifts the idle while the engine is cold. Take it off, or let it wear out, and the engine will run once warm but won't start cold. Setting the carburettors rich to make up for it doesn't do the same job.
Cranks with spark and fuel, but not even a splutter from cold; the AED has been removed or bypassed.
Prove the ignition first: a spoonful of petrol into each bore, plugs back in, crank — it should catch briefly. A short burst of starting fluid does the same. If it catches, the cold enrichment is what's missing.
Worth trying: refit the AED with its bimetallic top swapped for a cable-operated cam kit, then return the carburettor settings to standard.
Fuel-injected V12: no trigger to the injectors after work in the V
On the injected V12, the ECU times the injectors from an ignition signal carried on a small screened wire from the amplifier. That wire is easily broken during jobs in the vee, such as cam cover gaskets, and then the injectors stop firing.
No start straight after work in the vee; it tries and dies, or fires briefly only when the injectors are first triggered by opening the throttle.
Listen to an injector with a stethoscope or use a noid lamp: it should click all the way through cranking. Clicks that stop mean the trigger wire. Keep your foot off the pedal while cranking, and check the auxiliary air valve opens when cold.
Worth trying: repair or renew the screened wire between the ignition amplifier and the ECU, and set the idle back to standard.
The order to check them in
The point of the order is money: each step either rules a cause out or makes the next one worth doing. Green is free, amber costs a little, red is the one to arrive at last.
Key on, engine off — listen for the fuel pumps
They should tick and then slow as the carburettors fill. Silent at key-on but running while cranking: look at the pump relay and the ignition switch.
freePark or Neutral, handbrake on — wiggle the selector
Turn to Start and listen for the starter relay on the bulkhead. If it cranks only while you wiggle, it's the inhibit switch.
freeTest lamp at the fuel pump
Lit with the ignition on and the pump still silent: the pump's points or its earth.
freeLook for a spark
A spare plug against the head while cranking, and 12 V on the white/black wire at the coil with the ignition on.
freeProve the ignition with a little petrol
A spoonful in each bore or a short burst of starting fluid. If it catches, fuel or cold enrichment is what's missing.
freeOn the injected V12, listen to an injector while cranking
It should click all the way through cranking.
freeBypass the starter relay
Same whirr and click with the relay bypassed: fit an extra earth cable and try again, then take the starter out.
cheapWhat it usually isn't
Don't spend money here first:
On jagaux.com
- Jaguar XJ6 Series 2 Misfire, Rough RunningIf it starts but stumbles, cuts out or misfires once warm, start there.
- Jaguar VIN decoderConfirm your exact model year, engine and factory options before ordering parts — free.
Ratings, fuse numbers and torque figures vary by model year and market. Read the legend on your own car before pulling anything, and use the figures in the manual for your car, not the ones in a video.
Check your VIN: exactly which car you have and which bulletins apply to it.