Problems with a 1988 XJ6, 115k miles.
She was running fine but one day, on a bumpy road, she cut out and now will not restart.

More info, car drove home after the bumpy road and started stuttering in the driveway. Parked and now will not start.

"Mechanic friend" looked at it and declared it was getting fuel and spark, but wasn't sure where the carb inlet was to spray ether - so thinking this might not be a mechanic familiar with Jaguars.

I am going to look at the car next weekend, with a view to purchasing/rescuing her.

I will take some tools and a copy of the fault finding chart. sounds like it is not the inertia switch as first hoped for :-)

 

Hi cooldood,

Despite thousands of recommendations in the forums to "check the inertia switch," it is almost never the inertia switch. But that doesn't mean it isn't prudent to rule it out.

My first question is whether it is possible the car received some contaminated fuel prior to the emergence of these symptoms? Could the fuel filter have become clogged with water?

My second question is what is the state of health of the battery? If the voltage falls much below 11V while cranking, the engine control module (ECM) will not trigger the ignition to fire.

One simple thing you can do is to check the Vehicle Condition Monitor (VCM) for any stored Diagnostic Trouble Codes (DTCs). To do so, turn the key to position II (ON) but do not crank the engine. Press and release the VCM button on the trip computer to the right of the steering wheel, and watch for message to appear in the small display below the speedometer where the odometer/mileage display normally appears. DTCs appear in the form of "Fuel Fault" or "FF" an a single-digit numeral, as in Fuel Fault 1 or FF6.

Here's a chart of DTC definitions:


The mechanic who confirmed fuel and spark - do you know by what methods he or she did so? It would be worth confirming the work. It's easy to test for spark by pulling one spark plug, reconnecting it to its high tension lead and laying it on the camshaft cover so the threaded sleeve touches the aluminum cover for a ground path. Crank the engine and watch for spark at the plug.

An XJ40 has no Schrader valve on the fuel rail for testing fuel pressure, but you can at least check for the presence of some fuel under pressure at the rail by disconnecting the inlet hose at the end of the fuel rail near the firewall/bulkhead, and aiming the hose into a suitable catch container. I can't remember if the fuel pump in an '88 runs for a second or two when the key is turned to position II (ON) without cranking the engine, but try it to see. If no fuel flows out of the hose, try cranking the engine. You can probably tell visually whether sufficient fuel pressure and flow are present.

A common cause of rough running or stuttering is an air leak in the intake plumbing between the Mass Airflow Sensor (MAF) and the intake manifold gasket. Common leak points are cracked crankcase breather hoses, collapse of the intake elbow junction with the accordion hose at the front of the throttle body due to the hose clamp having been overtightened, a stuck-open EGR valve or carbon canister purge valve, or any of the vacuum hoses.

There are lots of other possible causes of rough running or stuttering, electrical issues such as a failing crankshaft position sensor (CPS), loose or corroded electrical connections, loose or corroded battery terminal connections, a corroded engine ground strap, a failing king lead between the coil and distributor, a distributor cap that has cracked or is damp with condensation, worn distributor rotor and cap terminals, poor connections at the ignition coil or amplfier, a failing relay (e.g. fuel pump relay, ignition ON relay), water ingress into the ECM or corrosion on its electrical connectors, cold solder joints in one or more electronic control units (ECUs) or on fuse box circuit boards, a failing MAF, oil contamination of the throttle position sensor (TPS) or its electrical connector, low or uneven cylinder compression, etc.

The good news is that problems with an XJ40 can almost always be diagnosed if you are systematic, patient and persevering. Please keep us informed.

Cheers,

Don

 

Thanks for that Don.
I am slowly assembling a collection of notes, info and questions to ask.
I doubt I could be so lucky as for it to be the inertia switch, but I will certainly check that.
The car is in California, and I believe always has been, so not expecting too much issue with major corrosion, but will go through that in troubleshooting anyway and certainly check within connectors.
I think I will be doing the spark plug trick, or the version where you pull of a lead and put a screwdriver in and lay that on something earthed, and looking for fuel delivery.

I expect at 42 psi, there would be quick the stream from the hose feeding the rail and quite spray/cone from an injector?

Hopefully the rest of the car is in good enough condition to make the gamble on the engine relatively low risk.
Trying to recall if it was raining in CA 2 weeks ago, I will need to ask, and when he last filled up. I will take a can of starter fluid and see if it will run on that.

Thanks again for the suggestions, I will post again after I see the car on Saturday.
John

 

Hi John,

It's prudent to do the spark plug test first as you mention, so you don't have spilled fuel in the engine bay while an exposed plug is creating sparks!

Please keep us informed.

Cheers,

Don

 

Thanks for this post, it is the first time I have seen code 1 as o2 related and not cps.

 

Okay, the car is home, but little progress made so far.
With jump leads connected, she turns over quite happily and tries to fire up, but not quite there.
I did have time to check the spark and all seemed well there, old plug connected to lead from coil showed multiple sparks, connected to plug lead there were sparks evident again.
Have not had a chance to check fuel supply yet, but pretty sure I heard the pump run each time the key is turned on. Removal of gas cap produced hissing air noise, expect a vacuum there, either as fuel is moved around the system, or from emissions control?
Did witness that there was standing water around the gas filler cap, the drain tube was blocked, but the hissing air noise suggests the cap does a good job of sealing and not thinking there is excessive water in the fuel from that source, but maybe? (Drain is cleared now)
Battery was completely flat and has been charging since the car came home.
Will likely not get a chance again until next weekend, by which time I hope to have a good battery, a fuel pressure test kit and a can of starter spray. Fingers crossed!

 

Hi John,

Low battery voltage while cranking is still a possible contributor to your current no-start, but it wouldn't explain the original symptoms of cutting out while driving on the bumpy road. I still suspect water in the fuel as a possibility.

The vacuum at the gas cap does suggest the cap is sealing properly, but what if the cap has not always been fully secured? The standing water in the gas filler gaiter can easily find its way into the fuel tank (the vacuum will help suck it in through even a tiny gap). I recently tracked down a no-start issue on a '93 XJ40 to lots of water in the tank due to a blocked drain in the fuel filler gaiter.

It's easy to test for water in the tank and in the process learn if the fuel pump is operating:

1. Disconnect the fuel inlet hose at the firewall end of the fuel rail (two wrenches required, I can't recall the exact sizes but I think they're somewhere in the range of 17mm/19mm and 21mm/22mm).

2. Aim the fuel hose into a suitable catch container. It helps if it is transparent or at least translucent. I used an empty/clean clear glass jam jar.

3. While one person aims the hose securely inside the catch container, another person should crank the engine for a few seconds until the catch container is about 1/2 full. If no fuel flows into the container, the pump is not running so you will have to diagnose the cause.

4. Set the container somewhere safe and allow the fuel to decant for awhile, maybe 30 minutes. When you check back, look for a line in the fluid indicating water at the bottom and fuel floating on top. On the '93, about 2/3 of the fluid was water!

If you do find water in the tank, the easiest way to remove it is to attach a longer hose to the fuel hose (still disconnected from the fuel rail), and aim the longer hose into an empty fuel can sitting on the ground beside the car. Gain access to the fuel pump relay (the location varies by model year), remove the relay, and install a jumper across terminals 30 and 87 in the relay socket. A paper clip bent into a U shape works well as a jumper. Now, when you turn the key to position II (ON), the fuel pump will run continuously, pumping the water at the bottom of the tank into the fuel can.

On the '93 we ran about 7 gallons of fuel/water out of the tank. I then reconnected the fuel hose to the rail and reinstalled the fuel pump relay, and the engine started right up.

Cheers,

Don

 

Thanks for the reply Don.
I might get a chance tomorrow to spend a little time on the car, so I will try collecting the fuel. I have a glass jar that would be ideal for that.

I will also be able to see if the battery has taken a charge.

 

The most important issue with the battery is the voltage sag while cranking, but if you had spark while cranking, the voltage should be sufficient for the ECM to trigger the ignition.

 

Installed the recharged battery today and she fired right up.
Oil pressure was slow to appear, so I switched off and looked around, then tried again. Still took a longish time but it did come up. There was quite a lot of light blue smoke out the tailpipes but took her for a short drive and that cleared up too. Expecting that is valve stem seals and will be a frequent nuisance, will see how bad it is in everyday use.
As warned, the brakes are not terrific, apparently a new master cylinder was installed, so I will bleed the brakes this weekend, and pay attention to the rears and running the electric pump to force the fluid through, hopefully that helps.
Most other electrics seem to work apart from one rear window, and the hifi. Thinking AC is not working and the rear door handles are intermittent, along with the fuel filler flap. Will get the door cards off and lube and adjust as necessary.
Idle was little lumpy, will go through fairly major service and see if that cures it.
Thanks Don for the good advice.

 

Good to hear that she running now, Re the door handles, if they feel iffy its because they are. One trick is to apply slight pressure with your knee to the door panel as you pull on the handle. This should alleviate the situation until you can get inside the panels to inspect the linkages.
If the rear window is inop from both switches then its in the door, if its inop from the drivers door then its more likely the switch pack, these can be opened up and the contacts cleaned.
Don’t be fooled by checking with an ohm meter to check for continuity the contacts can allow voltage through but insufficient amperage, as me how I know

 

Got some time with the car today.
Got her up on axle stands, wheels off and bled the brakes with fresh Dot 4 fluid.
Tried the ignition at position 2 and press the pedal to let the pump push fluid through the rear calipers, but heard no pump running nor fluid moving, had to bleed manually. Very clear improvement from brown fluid to the new clear-ish stuff.
On the test drive, the low pressure warning went away, but still have a message about anti-lock failure. Pedal feels unusual, often too soft on the first press, but good on second press, then good, then bad, then.... never quite sure if they are going to need one or two presses. All discs show signs of use, surface rust that was on them has worn away. I guess I am off to read more about the braking system. Did notice on visual inspection that rear pads are low, and on arriving home noticed low pad warning message.
One hanger on the right back silencer has one loop of rubber broken, so still supports the muffler, but allows it to bang against the boot wall, so will source one of them and a missing wheel stud needs replaced.
Tomorrow is polishing and door disassembly to investigate one window not working and adjust door locks.
On the starting side of things, she has been starting fairly well, but usually takes two tries. I note the battery is a Napa, rated for 550 CCA, and most sites suggest 800 CCA, so perhaps a trip to Costco for an Interstate battery might be on the to do list.

 

On the point of starting, have you tried cycling the ignition switch once or twice before attempting to start?
What can happen is the non return valve fails and the fuel pressure drops below optimum, the first attempt charges the fuel rail and at the second attempt the pressure is sufficient to fire the engine.
You only need to flick the key on for about a second then repeat maybe twice more.

I replaced my non functioning non return valve with a generic one under the bonnet.

 

Regarding your brake system, I am attaching the Power Hydraulic System manual that explains the operation of the (fairly complicated) brake system. My first impression is that your accumulator sphere may be failing. See the manual for a simple accumulator test.

Regarding batteries, I've been having excellent results with the Exide Global Extreme batteries, available at very reasonable prices from, of all places, Home Depot. Our member Box discovered these while searching for a battery that could work in the later X350 that has a higher-than-typical charging voltage range. The size 34 Exide Global Extreme battery is rated for 960 cranking amps, 800 cold cranking amps, and at our local HD it's just $94 plus tax. See the link below:

https://www.homedepot.com/p/Exide-Ex...-34X/204852596

Please confirm the correct size for your car - I just guessed from vague memory.

Cheers,

Don

 

Robman, I had tried that,, three times turning key to position II then back, first time the pump runs for 2-3 secs, then probably 1 sec or less on the other two, so thinking pressure has built successfully, but thanks for the suggestion.
Don, I see Costco has an Intestate for $83, with 1000/800 amps, size 34 seems appropriate. Item Number 850241
Reading Haynes manual tonight states cars with power hydraulic system do not have electric pump assisting brakes, but use the hydraulic system. Judging by disconnected lines under hood and at rear left side, I think I had self leveling suspension, but that has been deleted, so I should not have the electric pump, hence lack of noise/assistance.
I think the power hydraulic system does assist the brake servo, and may be low on fluid, so that will be attended to next. Reading your manual now and it is helping to clarify my understanding of another new system. I saw the ride height sensor at the back of the car, behind the spring/strut in front of which is the disconnected end of the pipe coming from the engine bay - I need to find the instructions for the self-leveling delete (now found in Haynes manual) and see if everything was done appropriately.
Off to order brake pads, wheel stud and hydraulic fluid.
Thanks again for all your help and patience.
John

 

Hi John,

On your '88 the hydraulic pump is mechanical and driven off of the engine, but you still have an accumulator, a combined low pressure/warning switch, etc., and the principles of brake power assist are essentially the same as on later cars with electric pumps. The pump pressurizes the accumulator, which has two chambers, one filled with nitrogen, and the other filled with hydraulic fluid. The two chambers are separated by a flexible diaphragm. When fluid is pumped into the accumulator under pressure, the nitrogen is compressed, maintaining pressure on the fluid. It is this pressurized fluid that provides the brake power assist (and before the conversion, the pressure for the self-leveling system (SLS)). When the accumulator fails, it can no longer store sufficient pressure, leading to warning lamps on the instrument cluster (on our '93 the warning lamps read ANTI-LOCK and BRAKE, if memory serves).

On your car, the pump and accumulator are at the front right of the engine, and if I recall correctly, it is easiest to access them from below, possibly through the wheel well. I replaced the accumulator on our '88 but that's been 20 years ago.

Cheers,

Don

 

Hmmm......trying to order the mineral oil is proving a tricky issue, with the special tube. Just how special is the tube? Can it be replaced with a syringe or another tube? Does it have a function other than getting the oil inside a small hole, does it open a port, needs to be a specific diameter, etc?
On the good news, the car passed smog, nice low percentages for HC and CO, so taking that as good news on piston rings and valve seals.
Leather is fed, paint is polished, wheels are shiny, all is good.
Sprayed silicone lube on each door lock and that made a huge improvement. One rear door had the card removed as I need to troubleshoot the non-working electric window, so I sprayed all the linkages and mechanism inside the door as well as around the striker. That worked so well I just sprayed the other three lock strikers without dismantling and they all improved leaps and bounds.
Off to AAA tonight to complete the registration documenting, beats trying to get to DMV with their shorter opening hours.

 

Hi John,

You're making great progress! How about posting some photos for the rest of us to drool over?

Regarding the mineral oil, it's been a long time since I owned a car that used it, but I don't recall the tube or spout to be anything more than a convenience for getting the fluid into the small fill hole in the reservoir. As far as I can recall, a small funnel should be just as effective.

Cheers,

Don

 

Thanks for the encouragement, always needed. Small steps, but all in the right direction.
Found another supplier and placed an order this pm, no cancellation yet, so fingers crossed they have it in stock. Agreed, as far as I can make out, the tube is nothing special, just hoping to have one on hand for the first fill up and then can use a different brand of mineral oil through the same tube in the future.
You want photos before she is really ready? I took some on the day we got her, I will look them out tomorrow. Not going to be fresh ones until the weekend, as it is dark when I leave and dark when I get back from work.

 

pics of the car, added larger versions to an album in my profile