Starting Problems Jaguar XJ6 1982 Sovereign

[brendanf]

Hello there from Perth Australia,

I have just bought a Jaguar XJ6 1982 Sovereign (imported from the uk in 1995 and not running.

I will try to explain what she is doing and what I've done, and been told to do and hopefully someone with knowledge about the 4.2 litre 6 with a degree in Lucas can help.

The car has been sitting for 2 years before I purchased it, and it worked when it was parked. The Engine was fully reconditioned by a Jag dealer 15,000 kms ago at an expense if some $15,000, so the fault can't be too major I would think.

The fuel might be a bit old, but I topped it up so it should be reasonable enough to start or @ least fire. The points & plugs are new, but the previous owner tried to fix the windscreem wipers and lost instruments on the dash (I think unrelated to the starting problem, but I could be wrong).


When you try to start it, it turns over great, and tries to fire, but just doesn't quite make it, very close though. I put starter fluid in the air intake after the airflow meter and it fires up and runs until the starter fluid runs out. I then tried spraying petrol (Gas) into the air intake of the air flow meter by holding the trap door open and it ran ok again, but it did blow the hose off on the engine side (scared the heck out of me).

I had a road side assistance guy come and try to get it to work, and he diagnosed the injectors as having very low voltage going to them, not 12 volts as thought, he thought it could be an earthing problem, but he wasn't sure so he gave me the name of a mobile mechanic with Jag experience. The mechanic said it was a computer problem and it would take a couple of days to fix (it's a plug in replacement,I thought he was only after what little money I have left).

I had the computer checked for faults by an electronics expert (no Jag experience) and he couldn't find any faults on the boards, I have a new one on order anyway.

With the low voltage to the injectors I thought it might be the ignition amplifier, I was told by Jagbits it was under the bonnet, but I can't find it, can someone tell me were it is please, maybe its unplugged.

Another guy said the airflow meter could need replacing, but would that cause low injector voltage? Anyway the previous owner did check it, and took the cover off the top @ some stage. I tried to start it by opening it half way thinking the air would help, but nothing changed.

Anyone with Jag experience, or knows someone to refer me too, or who is familiar with these faults, your advice would be greatly appreciated.

Cheers,

Brendan Perth Western Australia

 

[Deleted member 8987]

The voltage is measured to ground, so an earthing issue is probably not it.
If the fuel has sat for two years, it's toast.

You need to fully drain the tank, install new fuel, replace the fuel filter, open a line, activate the fuel pump (with ignition diabled) and pump a bunch out to clear the lines, then re-assemble and trry again.

Are the plugs wet?
Do they smell like old varnish?

If it ran when it was parked, and it was dry, the electronics just don't go bad sitting.

Connectors, yes, but you can open/close several times on them and that should self-clean.

 

[brendanf]

Thank's for getting back to me.

I will try the thing you mentioned now, and get back to you.

Thank's for your help, & I will get back to you soon.

Cheers,

Brendan

 

[brendanf]

Hi again,

I drained the fuel tanks, and the line to the injectors in the engine bay.

The fuel preasure was non existant until I turned the motor over and then it only came out slowly. I thought there was surposed to be a preasurised squirt from the ignition being turned on, I don't really know though.

It is surposed to be a new fuel pump (doesn't look that new) the fuel filter looks new though (quite a big one)

cheers

 

[brendanf]

I just checked the fuel pump lines again. when the ignition is turned on, there is a click in the trunk from thr fuel pump. I took the line off the injectors manifold while the ignition was off and I was sprayed with fuel. I think the preasure and the pump might be ok ?!?!

cheers

 

[Deleted member 8987]

Replace the filter.
You have no idea how much coagulated dead dinosaurs there are hiding in there.
If this is fuel injected, you will get a LOT of gas.
(Hence the warning to disconnect power to the ignition).

Pump pickups could be bad, flexible lines collapsed, who knows.

Fuel injected, lots of flow and presure.

Crank, yes, bypasses the fuel pump relay to cause the pump to run.
General rule is oil pressure signal or electronic distributor signal will hold the relay on.

 

[brendanf]

The spark plugs are dry too.....

 

[Deleted member 8987]

That means no gas.
I don't recall the pressure on that injection system, but it's higher by a big bit than carburetted versions.

Regulated pressure should be about 35-45 PSI, but unregulated (like, a hode off) about 80.
On a 3/8" ID hose, that'll squirt fuel 20 feet or more.

There were a couple of recalls on these.
Fuel pressure lines rotting, and cracking tanks, I think.

If you don't get a whole lotta fuel, you need to find out why.

 

[Exotexs]

try this test:

sit on the driver's seat,

place the shifter in 1st gear,

turn the ignition switch to start the engine as you turn your right ear to the rear seat,

you should hear the fuel pump 'whirring' or 'buzzing' as you turn the ignition switch to start the engine. (note: the engine will not start but you should hear the pump).

then follow the following no-start checklist:

https://www.jag-lovers.org/xjlovers/xjfaq/nostarts3.htm


The ignition Amplifier is a 2" x 2" black box which is hanging by two wires near the ignition itself. Inside it, it is a GM Delco module which you can find at NAPA auto Parts in the USA.

I think you don't need the computer at all, (ECU), those rarely go bad.

Another component to check is the INERTIA FUEL CUTOFF SWITCH
located under the right-most corner of the dash. It is meant to cut the fuel supply to the engine if the car flips over.

Sometimes this switch 'tripps' (like an electrical panel BREAKER does when there is an overload), when there is an excess of fuel pressure in the fuel system or when the car sits for long periods as is your case.

There is a button on top of the switch, press it down to see if you feel a 'click'. If yes the switch was tripped preventing fuel from getting to the injectors. If it is not tripped, you will feel it just springs back.


Ex

 

[jessebogan]

If the key is switched on, and you push the flap in the airflow meter, it should activate the fuel pump. You will be able to hear the fuel in the lines at the engine. This is the easy test to see if the fuel system works at all. Change the filter, and if your tanks are still empty, remove the large plug, and pull out the filters there too. Clean them off and replace.If you have points and condensor, you will have no ignition amp. Disconnect the fuel line at the rt rear of the engine, and tee in a fuel pressure guage. Pressures should be as mentioned above. You can also squirt some fuel into a clear container, and check for water or other contamination. If all is well there, check the temp. sensor for the injection. These were prone to failure, but the newer replacements (black plastic coated) are much better. Check the wires that go to it, and see that the metal connectors are in place in the connector. Check the ground wires at the rear of the intake manifold. Remove the bolt and clean rhem There is also a braided wire that connects the intake manifold to the head via the manifold bolts. Last thing, be sure that the inertia switch is not tripped, as this will kill the fuel pump circuit.

 

[Deleted member 8987]

"The fuel preasure was non existant until I turned the motor over and then it only came out slowly. I thought there was surposed to be a preasurised squirt from the ignition being turned on, I don't really know though."

This means the pump works, well, sort of.
Manifold vacuum has pulled the meter door open.
The relay engaged.

This is why I said new gas, NEW FILTER, before you proceed.

The screen in the tank, yes, and if still nothing, probably a bad pump, not running at speed.

Who knows what two years of bad gas did to it.

Not sure on that one, but I have worked on a fair number where the internal rubber hose between the tank pump and the tank fails.
I don't even recall if this one is inside the tank or outside.

If outside, possible a collapsed line between tank and pump, collapsing under suction.

You can throw a whole lotta money at this problem if you don't do proper troubleshooting, and eliminate the simple, normal wear items first.