OK that explains it - I misunderstood.
Your CPS was shot and it makes sense now.

 

Back to only the single pulse.

Re-pulled plugs, oiled cylinders, found 160-166psi compression (6 turns) across the board, which is quite acceptable. Put in new plugs. Verified spark. Verified fuel pressure is 42 psi at the rail. Verified fuel pump is running (comes on at key on; also able to jump the relay and switch it on). Injector circuit has power. Injector relay is operating. Have power in and out of it.

ECU is working (pulled MAF plug, immediately got IAT and air flow low voltage codes with RESTRICTED PERFORMANCE message on dash).

No DTCs.

I'm beginning to dislike this automobile.

 

Ok-

1. Spark, so you should have a burn if there is fuel- at least a little rumble.
2. 45 psi at the rail- so you have fuel up to the fuel rail
3. injectors- can you spray some starting fluid into the the intake to see if you get a little grumble? I know this is not the BEST course of action in the long term but it will let you know if it is between the injectors and the fuel rail.

If you have compression, fuel and spark it WILL at least fire a few times... so I think you still do not have fuel to the cylinders.

 

Is the throttle plate definately moving? If you remove the intake trunking so you can see the throttle plate, then with the ignition switched on you should see the throttle plate visibly moving when you press the accelerator.

Although you say you can hear the throttle motor noises, it doesn't necessarily mean the throttle plate itself is moving-you need to confirm this visually in case there's been a mechanical failure inside the throttle body where the motor connects to the throttle plate.

Just a thought-I did this with my car to open the throttle so I could clean inside the throttle body & around the edges of the throttle plate...

 

I'll double check in daylight tomorrow. The quadrant moves but that doesn't mean the plate is opening.

And yes, I've tried cranking and cranking and cranking and cranking and cranking with foot to the floor to no avail.

 

This is what's so frustrating.

I had neither fuel nor spark. Then I got fuel when I had no spark. Now I've got spark back and once again no fuel. I'm nearly ready to push this car into the river. I'll have to get a can of ether to see if it can be 'helped' along into firing off.

I might as well also replace the fuel filter I suppose... pressure ≠ volume... wondering if it might be a fuel volume issue. this could also still be a fuel pump issue with that in mind. I'm really out of ideas other than listing it on ebay as a parts car.

 

Before you push it into the river, there are several issues known to cause engine stalling on early XJ8's.

The first is carbon build-up around the throttle plate, which under certain circumstances can cause the throttle plate to jam closed & stall the engine. Early throttle bodies were known to be troublesome-there was also an issue with the motors that weren't strong enough to open the throttle plate under certain high engine vacuum conditions (high rpm on the overrun etc).

That's in addition to the carbon build-up which can jam the throttle plate, again starving the engine of air.

Also, there is another issue with the part-load breather pipe that can get blocked by carbon at the narrow restriction where the small hose enters the left hand cam cover. This can also cause air starvation & engine stalling.

The cure is to remove the part-load breather hose from the left hand cam cover, then use a 3mm drill bit to clear out the restrictor passage in the cam cover hose elbow & remove the carbon build-up.

If you have a coked-up throttle plate/body & also a coked up part-load breather restrictor, then you have the 'perfect storm' for engine stalling due to air starvation from all these carbon blockages.

Give these a check & good clean first-they were known issues which were well-documented in causing engine stalling on the early X308's. If the cars fires up (it could take several seconds of cranking), then it may emit some smoke from the exhaust as any residual carbon in the pipes gets drawn in & burnt off.

 

I am thinking about your problem but the one thing I must stress you do not shoot starter fluid into the throttle body.

 

The throttle plate is definitely crusty and carboned up, there's no question. The underside is a bit caked and the top side forward edge is blackened about 1.5-2cm in. I'll check the part load breather as well... anyone have pics of what it should look like as a frame of reference?

 

I appreciate that.

Another Jag guy who is also utterly baffled wants to run a security relearn on the car... In his words 'it may not help, but it won't hurt.' That kind of confidence is not terribly reassuring.

It is confirmed the cams are turning, but that doesn't mean they aren't out of timing. Preferably there is some way to determine that without surgery. It's just not an appealing proposition to tear open the top end needlessly to check a problem that doesn't exist or replace parts that aren't faulty...

 

If you have an alternating no fuel and then no spark cleaning the TB and partload breather is not going to help. However it may make you feel better. I have stuff on my page if you need it.

The last time we talked you said you had an issue with water have you checked and cleaned all the connectors? In the past we had I think 2 cars that had a bad fuse box. What was taking place was an intermittent power to the control, we also found that the grounding points were corroded resulting in near the same issue. You have my number give me a call if you wish.

 

I was thinking about the security but was not sure I needed a little more info. A better question was this car a repo and did they make a key and not program it? Is the light for the security flashing at any time? Well not a bad idea to check the security I would go with that for now.

 

I agree with your line of thinking, and may go through the grounds for the same reason as you suggest cleaning the TB and breather - peace of mind. But there are no other circuits that have failed. In fact, the injector and coil circuits have power all the way through. I've got power in and out of the ignition modules, and a hot bright blue spark with new Bosch Platinum II plugs.

Are there any connections you would recommend checking first if you were doing the work?

 

The part-load breather is easy to find, as it's a small pipe that plugs into the left-hand cam cover near the front of it. It has one of those 'quick release' plastic connectors on it. You just squeeze these & pull the pipe back, although it may be tricky to budge if you don't have the special little tool. If you're careful, long-nosed pliers can work.

Once you've pulled the pipe back away from the cam cover, you just put a 3mm drill bit into a pin-vice & then carefully put the end of the drill bit into the centre of the exposed cam-cover elbow. Then you slowly turn the drill bit by hand & let it clear out the blockage.

Don't use any form of electric drill!

If your throttle plate is all carbonned up, then it's fairly certain the part-load breather is clogged as well. Even if this doesn't cure the fault, it's one less area to check later & can be eliminated from the possible causes.

 

You indicated that spark and fuel alternate off and on is it still doing that or do you have both constant?

 

Part load breather stub JagRepair.com - Jaguar Repair Information Resource If you need it.

 

Spark with new crank position sensor is constant. When I had the coils off and was spinning the engine I had fuel enough to flood the cylinders, wet the plugs, and send raw gas smell out the tailpipes. Now the coils are back on with new plugs in and I've got no fuel again.

I can't help thinking the two are related even though separate systems are tough to have create a situation where one causes the other to fail/absence of one causes the other to operate.

Nothing on this car makes much sense. Once this car is running it'll go away and I'll go back to the Porsches I know, most likely.

 

The original symptoms were that the engine ran for 5-6 seconds, chugged & then stalled.

My thoughts are that if it was an electrical failure like a relay etc, then the engine would stop instantly without 'chugging', like you had normally turned the ignition off to stop the engine.

The fact that the engine 'chugged' before stalling may give some clues as to the nature of the fault. If the fuel pump failed, then once the engine had used up the fuel in the rails & the pressure falls, then the engine would chug & stutter before dying. I've pulled fuel pump fuses out on cars before & they don't stop instantly-they stumble first & then stall.

Apart from the fuel pump, other electrical failures are usually instantaneous & the engine stops cleanly without stumbling.

My suspicions are the carbon build-up on the throttle & part-load breather assemblies, as these could cause the engine to chug & stumble before stalling, as it tries to pull the air in past the blockage before the vacuum created then stalls the engine due to lack of air.

I'll put my money on the throttle body & part-load breather...

 

I'll give it a whack. Like taking the backroads to avoid slow highway traffic, it may not get me there faster but at least it's something to keep moving on while making no real progress.

It's just confounding that the car started perfectly fine one morning, sputtered a few seconds after, gave the message "engine stalled" and has given absolutely no hints past that. None of what has fixed others' cars seems to have any effect here. The car is probably going to have to be towed to someone who knows more about Jaguars and wants to unburden me of a significant amount of cash.

 

Of a similar mind.

I've ordered a fuel filter and o-rings for Monday just to put a new filter in and rule that out. Again, there's fuel pressure at key on but that doesn't always tell the whole story.