No Start XJ6 1987

Sadly this isnt a new post but I cant find the one I wrote 5 weeks ago! lol
Doug thanks for your help. I brought it to my garage and they cant figure it out either.
It Started out with a car that was running fine one day and wouldnt start the next.
Originally It had no injector pulse. I have pulse now but it still wont start.
I have pressure in my fuel rail, working fuel system, strong crank, injector pulse and spark yet still no start. I hear the click at the bullet connector of all the injectors but I have a feeling they arent spraying. I changed my injectors about 500 miles ago and the car was running beautifully…Here is what I have done:

Injectors: New
Ignition Amplifier: New
Pickup Coil: New
Fuel pressure: Good
Spark plugs: New and good
Spark exists
I have noid activity at the bullet connector

Could it be that all my injectors are fried at once? What are the Ohms supposed to be across the injector contacts? If I’m getting 0’s are my injectors done?

I am going bats&*( crazy with this and my garage gave up…hellllllllllp! lol :face_with_symbols_over_mouth:

So the plot thickens…I did a stethoscope on each injector and they are clicking on crank…i could hear each one…

Injectors click but do not spray???

  1. Make sure there is spark to the spark
    on cranking.

  2. Remove the spark plugs and squirt in a bit of gas in each cylinder. Replace the spark plugs. Crank again. Any combustion? If so it is a fuel issue.

Alternate. Open the throttle butterfly. Squirt in a blast of ether. Crank. any combustion? If so fuel issue.

No combustion, Probably no spark in the combustion chamber. An ignition issue/

Or worse, both!!! Two faults… .

First things is this a XJ6 S111 or the early XJ40?
If its the latter try these;
Have you tried flooring the accelerator pedal and cranking? The no spark may have caused the engine to flood. By flooring the pedal you are shutting off the injectors, and yes they fire together, 1/2 shots per revolution of the engine.
The other thought, is the cranking speed high, as in lack of compression? You may have bore wash.

I have done that and nothing. I have excellent compression- between 145 and 150 psi. I have spark and pulse.

Still not sure what engine we are talking about here.

What fuel rail pressure do you measure, Jeffrey…?

That items are new doesn’t mean that they are working, but since plugs spark and injectors click it sure implies that they are working.

Specific and important question; is there absolutely no response at all from the engine while cranking? Even with various problems; one would at least expect spasmodic firing…

Painted into a corner as you are, remove plugs and ‘dram’ the engine with petrol as Carl suggest - a teaspoon in each cylinder, replace plugs and crank. If the spark is strong enough to ignite petrol; the engine should catch and run briefly - stopping if further petrol is not supplied by the fuel system. Sort of separating a fueling from an ignition problem…

As asides; you have verified air ducting between AFM and throttle body, throttle gap and AAV slide half open? With the air duct disconnected or seriously leaking, or no air passing through the AFM; the injectors would still click, but too briefly for adequate fueling…

xj6 85 Sov Europe (UK/NZ)

Sorry- Its a 4.2. US Spec

Hi Frank,
I have absolutely no reaction whatsoever at the engine. Not even a stumble. I will try the direct petrol today and let you know what happens.

I will try the fuel today Robin. Its a 4.2. I did a compression test and have a consistent shy of 150 on the compression in all cylinders.

That’s extremely odd, Jeffrey - even with major problems; the presence of fuel and ignition usually elicit some engine reaction…

‘Draming’ the engine is a positive test of ignition; a weak spark, low voltage or lack of spark energy, may be unable to ignite petrol.

If there is no response to draming; I suggest three tests. Use a spare spark plug connected to any plug lead, but gapped to some 3 mm (0,1") and crank. The spark should be strong and blue - a weak, yellow, spark may or may not run the engine.

Remove the air filter and while cranking; gently push on the AFM flap - to increase fueling. This may counter possible air leaks, and may give some engine response - which will then imply that fuel is an issue. But also; the AFM may have a ‘flat spot’ in the crank deflection - and the ECU gets the wrong gen - and misfuels…

At the CTS; disconnect the plug and measure the resistance of the sensor - it should be some 3 Kohm at room temp. Then measure resistance between the two wires on the connector; it should be some 2 Kohm - but very important; there should be no variation in the resistance when the connector/wires when bent or twisted. Basically, this latter verifies the connection to the ECU. If the CTS or the wires are shorted; the ECU reads this as a very hot engine, and delivers too little fuel for a cold engine to catch/react, though the injectors faithfully click…

The tests are quick and easy, though not necessarily conclusive. Robins point should not be discarded; the engine may be flooded, excessive fuel may disable sparking - giving identical symptoms to ‘no fuel’ or ‘no spark’. So inspecting a plug after cranking is pertinent - wet plugs is also a clue…

xj6 85 Sov Europe (UK/NZ)

Ok thanks Carl/Frank. So I spooned some fuel to each cylinder and the car wanted to start so there was combustion in fuel chamber. It only lasted a few seconds obviously. So likely have a fuel issue. When cranking and using a stethescope I can hear the ticking of the injector so this is perplexing to me. Any suggestions?

Aye The injectors click but do not squirt. Clean the injectors.

  1. Send to an injector service.

  2. DIY/ Introduce a cleaner at the intake on the individual injector And energize via a 9volt battery… Any spray? No. Repeat. Yes. Not the issue…

1 Like

Thanks Carl but what would cause all 6 injectors to click but not spray. New injectors at that- all 6.

Nope, far more likely there’s no fuel inside those injectors to squirt. Each injector has its own tiny inlet screen, so a great big load of garbage coming down the line could have plugged them all at once – but that’s not likely. Far more likely there’s a single obstruction somewhere or a faulty pump causing a total loss of fuel flow.

The injectors are held open for milliseconds, the pulse width, Jeffrey - impossible to verify by listening, an oscilloscope is required…

The wider the pulse the more fuel is delivered; the main inputs to the ECU for calculating pulse width are the AFM and the CTS - check them as described. Too narrow pulse may deliver too little fuel for starting a cold engine…

As Kirbert and Carl say; the reason for no fuel may be there is no fuel to inject - which is why I asked about the actual measured fuel rail pressure; how did you check the pressure? If the fuel pressure is OK; either the pulse is too short or the injectors are clogged. To test injectors you have to to remove them and test spray patterns - or have it done professionally.

That 6 injectors, all new, suddenly fails to spray is certainly unusual. They may all be clogged up, but the main fuel filter should prevent that - have you checked the filter?

But the sudden onset is highly mysterious…

xj6 85 Sov Europe (UK/NZ)

  • is the fuel pressure in order? Easiest to check at the cold start injector - it will start without the injector in almost any situation
  • can you smell fuel at the exhaust after cranking for a few seconds?
  • is there a massive vacuum leak somewhere?

I forgot a brake booster vacuum hose one time. Another time I didn’t reconnect the large tube at the large elbow well enough and it wasn’t clearly visible, on the underside. Another culprit could be the AAV hose at the back of the manifold.
In those situations the injectors will click but inject too little fuel and the mixture will never combust. Maybe inspect the flap of the AFM while cranking. If it’s unbothered you know it pulls air in from somewhere.

It had to be the S3 engine, with the famous bullet connector - good luck!

Maybe not. On the V12 we had one owner send his injectors out for service by one of the reputable companies, and when they came back he let them sit for a couple of months before reinstalling. When he finally got everything back together, the engine wouldn’t start. Come to find out all 12 were plugged up and not squirting! Apparently when they test these injectors on a test rig, they squirt fuel through them, and if left to sit the fuel varnishes the pintles shut. It’d be smarter if they flushed them with something that didn’t varnish before shipping them back to the customer, but I guess the presumption is they’ll immediately go back on the engine and begin operation.

Hi Kirbert. When I first got the car, I replaced both fuel tanks, return valves, filter, changeover valve. line to fuel rail land all injector lines are new as are the injectors. Fuel pump and circuit are operating as they should.

Hi David,
My garage said fuel pressure is in order. I dont know the reading because they didnt tell me. They did however leave a schrader valve for me so I will hook it up but there is def strong pressure in the rail. The AAV hose and other vaccum i will check this weekend. Thank you.