G'day folks,

Please help, I'm about to go mad - I cannot start my 1983 XJ6 Series 3 VDP. I have replaced the following items:

ECU
AFM
Fuel Injection Diode Block
Both Fuel Injection and Starter Relays
Fuel Pump and Fuel Pressure Regulator
Fuel Injector Wiring Loom
Power Resistor Pack
Ignition Coil
Coolant Temperature Sensor

I have checked all vaccuum hoses and earths, as well as the usual basics. The engine fires immediately, and then stops immediately. It will not refire after the first attempt, but will fire again if left for a while, but then as soon as it starts it stops within a second or so.

I have gone through all the various checklists found on this and other forums, but am left stumped. What am I missing here? I am going insane, just need to get the vehicle started so I can get it to my mechanic for a professional fix and tune.

Any advice would be greatly appreciated before I take drastic measures and buy another car that works more than once or twice a year.

Thanks.

 

You could check the Inertia switch which is the fuel cut out switch in case of accident it is on left hand side by A pillar just bellow glovebox on R/H drive cars i dont no if the same on L/H cars. Also late series 2s and series 3 not all had a single terminal switch i think it is called a pess switch at the back of the engine block about half wayup the block on the right hand side (sitting in car ) This switch was designed to cut engine when oil pressure got to low but some times can be faulty when oil is ok The part number for inertia switch ( DAC1761) part Number for press switch (JLM9619).There is also an inhibit switch part DAC2726 on left hand side of gear box if Auto it is the switch thats starts you when in park or nutural only and can get oil and dirt on terminals and will not start it also serves as your reverse light switch. Hope this helps
Cheers Ray

 

Welcome to the forum.

Have you done any diagnostic tests yet or have you been only swapping components out? If you have definite info on full pressure, presence of voltage etc, you should post it now for the guys that follow who know what they are talking about. Might save a bit of too-ing and fro-ing

 

1) definitely check the Inertia Fuel Cutoff switch suggested by on edge; If the car is a USA car, the IFC is located on the front passenger side, below the dash, behind the kick panel.

it is a black box with a red pushbutton on top, and a plug with wires at the bottom. Press the button and if you hear it "click", then it was tripped, the engine should start after a reset.

2) place the shifter in 1 (first gear). Turn the key to start; Do you hear the fuel pump priming the system when you turn your ear to the trunk? It sounds like a "hhmmm-click".

3) check the Cold Start Injector; Unscrew the hex screw holding the CSI in place, have someone else crank the engine in PARK, watch for a spray of gasoline while holding the CSI.

 

1. One of my favorite no run diagnstics is to jump 12v rom battery+ to the post on the igniton coil

 

sorry forum stalled!!


1. Jump battery + to coil +, crank engine. If it fires, then work back with test lamp or VOM, to see where the break is. Oddly, I am in a similar fix, not yet resolved. Lots of thrashing, more to go.


2. Use the timing light to detect spark at the distributor to coil wire and beyond to each HT lead. as your car fires, one and two will possibly be inconclusive.


3. Bridge any OP ignition interrupt. It and the inertia switch are redundant.


The neutral start/ reverse lamp switch on the transmission can be troublesome. But, it interrupts the crank circuit only. No effect on the ignition circuit.


Question: Does it fire on crank, the cease when the key is released to run? Clear cue as to a switch or wire or connector issue.


Good luck with the electrickery!!


Carl

 

I wonder if the fuel pump stops running after you release the key from the 'start' position?

I'd suggest bypassing the fuel pump control circuit.

Remove the fuel pump relay. Locate the contact inside the socket with white/green wire. You might have one or two white/green wires at the socket. Using a jumper wire apply 12 volts to the white/green wire or wires.

You should hear the fuel pump run. If you don't, you have a problem downstream of the relay.

If you DO hear the fuel pump run, try starting the engine. Does it stay running? Post back!

Cheers
DD

 

5 people have offered help ...... crickets

 

Hello again,

Thanks for the responses, delay in reply has been due to poor internet coverage (keeps dropping out) and me not being mechanically minded enough to apply these tips quickly enough - too old, too slow.

The car will not fire at all now, turns over, but does not fire.

I have checked the inertia switch, it wasn't tripped.

I can hear the fuel pump working, but have no diagnostic equipment to check pressures etc.

I have checked the neutral safety switch, that seems fine also.

It is Easter Monday tomorrow, so I shall attempt to replace the cold start injector and double check the checklists.

Many thanks once again.

As an aside, can the inertia switch be bypassed if necessary?

Cheers.

 

Do you have spark?





As you wish but a dead cold start injector is unlikely to cause a no start problem. Hard starting/extended cranking would be the mot likely result. I had an inoperative CSI once and never even realized it....until really cold weather hit.





Yes, it can be bypassed. But....don't bother. What the inertia witch does, if 'tripped', is cut power to the fuel pump circuit. Since you can hear the fuel pump running the inertia switch is OK.

Cheers
DD

 

the logic behind checking the CSI is to easily check if fuel is being pumped.

so if it is not a fuel supply problem, then it comes down to the ignition.

check the ignition Coil using Carl's bypass trick,

check the Ignition Amplifier, which is a small black square box hanging near the
distributor. These amplifiers are a known issue. (a GM/Delco amplifier).

if you replaced the injectors' harness, check for a small ground strap at the top rear end of the cylinder head, there are two ground wires there including the strap.

 

An update on my progress, have narrowed it down to plenty of fuel pressure but definitely no spark.


I have checked all earths, wiring and connections. Have checked the HT leads, ignition switch, fuses but am a loss as to why I'm not getting a spark all of a sudden. The coil is new, as are the fuel injection diode pack and relays.


I even resorted to refitting the cars original ECU, made no difference.


There was only one earth lead on the injection harness, and that is well earthed.


I will change the ignition amplifier and buy some proper diagnostic tools this week and tackle it again on the weekend. I need a few days for my back and neck to recover.


Many thanks for the advice fellas, I didn't anticipate Jaguar ownership would be so testing!


I am considering sourcing a Series 1 XJ6 instead, in an attempt to get back to the purity of carburetted cars and I figure far less headaches than the Series 3 fuel injection gubbins.

 

check the following XJ Parts Interchange page for more info on the Delco Ignition Amp.

XJ Parts Interchange Guide

 

The first thing to be aware of is that the ECU is not really an ECU in the modern sense, because it is nothing to do with the ignition, which is completely separate on the XJ Series 3, the ECU only controls the fuel supply to the engine. There is a link between the two, because the ECU needs an ignition system pulse to time the injectors, so there is a feed of the low tension ignition pulse to the ECU. So if there's no spark, usually there's no fuel supply either !

Have a read -

Fuel injection and the Jaguar XJ6 4.2 Series 3 / AJ6 Engineering

 

Here's some trouble shooting info on the CEI ignition


The test assumes a fully charged battery

1) Measure voltage at coil "+" terminal with key "on". It should be within
one volt of battery voltage. If not suspect a problem with the wiring to the
ignition switch, or the switch itself.

2) Measure voltage at the coil "-" terminal. Result should be the same as at
the "+" terminal. If Ok, go to step 3. If not....
Disconnect the wire from the amplifier from the "-" post of the coil and
measure voltage again. Less than 2 volts means the coil is faulty. More than
2 volts means the amplifier is faulty.

3) Disconnect distributor pickup coil from the amplifier (this is the
harness from the distributor that plugs into the amp). Measure resistance
across the terminals. It should be 2.2k to 4.8k ohms. If Ok, go to step 4.
If not, replace the pickup.

4) Reconnect the pickup to the amplifier. Measure voltage at coil "-" post
while cranking engine. The voltage should drop. If OK, go to step 5. If
not, the amplifier is faulty.

5) Check distributor cap and wires, distributor rotor arm, spark plugs, coil
wire


Cheers
DD

 

Thanks guys for the invaluable information, it is priceless to novice Jaguar owners like myself.

I am swapping parts over from a 85 Sovereign that was my daily driver and working perfectly until a blown head gasket a few weeks ago.

This afternoon, I removed the ignition amplifier from the 83 VDP I'm attempting to start and the wires are stuffed. I also note on closer inspection the wires to the throttle switch are hanging on by one or two strands, so I have some rewiring to undertake.

I have printed off all this thread information, and it will serve as my checklist. Much easier to understand than the Haynes manual.

Have also got some diagnostic tools, so will get stuck into this on the weekend.

I cannot thank you all enough for sharing your information, it is a wonderful thing.

Cheers.

 

Does your new tool kit include a test lamp? If not, easy to make one. from primitively simple to a tad sophisticated.


1. Use a single filament 12v bulb. I used one with the center lead contact worn to the point that it fit too loosely to be reliable. Solder a red wire to the center lead contact.
Solder a black wire to the brass end. Bare wires twisted tight on the other ends will do.


2. Use a spare small receptacle and do the same.


3. Add an inline fuse in the red lead.


4. Add a 9v battery or two for self power in the red lead.


Carl

 

Hello again folks,

What a learning experience this has been!!

Having replaced everything that promotes fuel, spark and air to cooperate to make noise, and having followed all the tips and advice given here and other places, the old girl still would not start.

Literally on the brink of buying another car until I decided to swap over the brand new relays I had installed. The car started, ran very erratically but at least it fired.

No matter what I did I could not get it to idle or run properly. So I replaced the brand new genuine Bosch AFM with the one from my Sovereign, and bingo - she purrs like a cat again. She now runs faultlessly.

So, the very first things I replaced were faulty, or not the correct relays sold to me by the local Jaguar specialist. I could've saved a load of annoyance, stress and backache but at least I now have a better understanding of how a Series 3 operates.

Thanks for your tips guys.

Now to tackle the head gasket in the Sovereign.....

 

congratulations! what a battle. Considering the early change over to what should have been good parts , its a wonder you got this resolved. You are a persevering kind of guy :-)

 

this has been a great thread for me to read.
I've just replaced ignition module and coil. the car backfired through the air intake a couple of times, then ran well. today it would start, but only hold revs if I held the throttle on. no idle at all. after reading this, I may try another afm on the old girl