No start help
 

I just bought a 94 VP that was not running when I got it. When I got it home I put it on charge. The first time I turned the ignition on and hit the VCM button I got code 22. After trying to crank a few times the code went away. I have read through a few threads and some service manual sections with no luck.

Here is a list of what I have done,

-Verified spark (weak)
-Fuel pump primes
-Jumpered between 30-87 on fuel pump plug to make sure it runs
-Switched injector, ignition, and 02 relays with known good ones
-Compression checked each cyl. All were good
-Cleaned cap and rotor surfaces
- Checked all fuses
-Had battery on charge, tightened and cleaned all connections
-Cracked a fitting on fuel rail. Definitely under pressure
-Tried starting fluid

It coughed a few times like it was going to run but it didn’t. After trying to start multiple times no VCM light came back on. I don’t know how finicky these cars are with fuel pressure, but it’s definitely getting it to the rail. The spark looked very weak. I just faight a hard start bad miss on my s10 and it had a spark similar to this.

I’ve checked all the obvious things that I can think of. Possibly my next step it to try a coil. It looks like it has a capacitor with it too. I really dont don’t want to throw parts at this car though.

Any help would be greatly appreciated!

If I remember correctly, the 1994 MY was notorious for corroded fuel rail.

I cleaned many rails of rust and replaced or cleaned the injectors.

It should start with 'carb-spray' or similar if the injectors are clogged, but won't stay running.

The dist rotor can fail and 'short-to-earth'. I used to keep a spare 'good-used' in my tool box for verification.

bob

Externally the fuel rail is in good shape as well as the fuel lines. I will be changing the fuel filter before the car hits the road.

I did try starting fluid and it didn’t help.

Now I have never seen a rotor shirt out, but it could possibly be causing my weak spark issue. I didn’t notice any tracking from the rotor to the distributor shaft, but I wasn’t really looking. I will check that tomorrow.

Hi Tonyorlo,

One common problem with XJ40s that have been sitting for awhile is water in the fuel tank. There is a drain tube in the rubber "gaiter" around the fuel filler neck, but the drain typically clogs up with seeds and leaves, which then allows water to pool around the fuel filler neck and make its way past the cap seal and into the tank. Last year I pumped 5 gallons of "fuel" out of a '93 that would crank but not start, and discovered that about half the "fuel" was rainwater.

An easy way to test for water in the tank is to disconnect the fuel hose from the inlet end of the fuel rail (closest to the firewall), slide a piece of suitable hose over the end of the fuel hose (I think I recall that standard 5/8 inch I.D. heater hose works). Aim the other end of the hose into a transparent catch container. Remove the fuel pump relay and jump the socket as you did before to force the pump to run. Pump at least a quart of fuel into your catch container, then set it aside for 30 minutes or more to allow it to decant. Then check it for a line indicating water has separated out and settled to the bottom of the jar.

On another topic, having a "charged" battery is not enough with Jaguars. On an XJ40, if the voltage while cranking sags much below 11 volts, the ECM will not trigger the ignition to fire. But the fact that you have weak spark probably tells us the ECM is trying to start the engine.

Common causes of weak spark include high resistance at one or both ends of the engine ground strap (which is the ground path for spark), incorrectly gapped spark plugs, incorrect spark plugs (the OE Champions seem to work best in these engines), high resistance in the spark plug wires (the king lead from the coil to the distributor cap is common to all spark plugs), worn distributor cap terminals and rotor electrode, problems with the coil or ignition amplifier (check for problems with the connections at the coil and amplifier), and possibly corrosion on the ground points referenced by the ECM (the two on the intake manifold and the one on the firewall behind the cylinder head).

Also subject to common problems and possible contributors to weak spark are the battery terminals and battery power connections throughout the vehicle. On your '94, some critical battery power connections are the firewall jump post, alternator, starter, and the point where the battery ground strap bolts to the right rear inner wheel well. The power connections at each fuse box are also worth cleaning, but a bit time consuming to access. Obviously, disconnect the battery before disassembling and cleaning any of these connections.

It would also be worth cleaning the electrical connector for the Crankshaft Position Sensor (CPS) just in case oil contamination may be weakening its signal amplitude. Because CPS failure is common and can cause difficult-to-diagnose gremlins, including non-starting, many XJ40 owners replace the CPS with a new one and put the old working one in the trunk as an emergency spare.

I wouldn't worry about the trouble code on the VCM for now - the FF22 may be spurious or due to low battery voltage. As long as you have reasonable pressure at the fuel rail your injectors should be able to squirt at least some fuel onto the backs of the intake valves.

The definitions of the diagnostic trouble codes can be found in the Haynes manual. You can download a partial copy here:

Haynes Jaguar XJ40 Repair Manual

Cheers,

Don

Don,

Thanks for the Replies!

I will most definitely check for water in the fuel. I am unsure how long this car sat before I purchased it, the fuel could just be bad. I will try pumping some of it out and letting it settle. I may just go ahead and pump most of the tank out.

The battery was dead when I got the car, I put a charger on it for a few hours. The voltage gauge was between 12 and 13. If I continue to have problems I will put a trickle charger on it over night. The battery connections were both loose when I got it, and the ground cable connection to the body was loose. They did seem clean though.

I have not went through the connections under the hood. Everything under the hood appears to be in good shape, the car was maintained very well through its life. I will go through all the ground connections under the hood.

If if I could get a cap, rotor and plug wires locally I would probably try them. The previous owner changed the cap and rotor around 2010, which I guess was 9 years ago now. Usually if a coil goes bad, its dead in the water right? They don’t go slowly.

Thanks again for for the help!
I will report back with my findings.

Hi Tonyorlo,

There is a very good chance that your battery voltage while cranking is sagging so low that the ECM may only be intermittently triggering the ignition. Connecting another vehicle in a jump-start arrangement might be worth trying, but in my experience Jags don't always respond to that if their own battery is weak. You can't rely on the instrument cluster voltage gauge - it's usually not terribly accurate, and it can't react quickly enough to give you a true reading of cranking voltage sag.

You really can't visually judge the cleanliness of the battery and ground connections. It only takes a microscopically-thin layer of oxidation to add considerable resistance to a connection. So anytime you disconnect one of these points, clean all parts with a brass-bristle brush and zero-residue electronic cleaner, allow to dry and reassemble. Also, dielectric grease is fine on the outside of the assembled connection, but don't apply it to a battery post, ground stud, etc. prior to assembling the joint, since dielectric grease is an insulator and can add resistance to your connection or reduce the area of actual metal-to-metal contact.

Coils can definitely fail "partially," with internal shorts and other issues that cause them to produce low voltage output or to work intermittently. But if your weak spark seems consistent, I would focus on other issues first, such as water in the fuel and a weak battery.

Cheers,

Don

I did have a customer with a 1994 XJ40 with a 'rusty' fuel filler cap surface and left the car in the drive way under trees.
The fuel scupper drain got clogged about once a year and I had to get the car 'wreckered' to my shop to drain the fuel.

The water would accumulate and creep in under the cap. Since the sealing surface was corroded, the water had no problem contaminating the fuel.
I tried to polish the surface but did not get aggressive to the point of causing 'sparks'!

I added fresh fuel and replaced the filter.

Next year...........Same thing!!!

I think she sold the car because I have not seen it in several years.

bob

Well I drained the fuel tank and put fresh fuel in. I also changed the fuel filter and spark plugs.

I tried starting it and it coughed like it was going to try something but never ran.

I found the - lead on the coil a little loose. I thought I had found it, by I didn’t. I decided to measure resistance between the primary and secondary side of the coil. I got 7.29k ohms, and from what I have seen posted it should be between 5.4k and 6.6k ohms. Maybe that’s the problem! I’m going to pick up a coil tomorrow and try it.

I do plan to change wires, cap and rotor. I just really want to find out why the car stopped running before I got it.

Does the rev counter register anything when you crank the engine? 200 rpm or so?

Larry

Yes it does, just about 200 rpm.

Reporting back with some findings and questions. Still no start.

To recap what I have done and checked,
Charged battery
Cleaned battery connections
Had charger on battery, with 200 amp boost
Jumper cables from truck
Installed truck battery in car
Added ground cable from engine to body
Drained fuel tank
Replaced fuel filter
Replaced coil
Replaced plugs
Jumpered fuel pump relay
Can smell fuel on plugs with Relay in
Cleaned grounds by fuel rail
150-200 rpm during cranking
Ignition on, 12v at coil and stud on firewall
Cranking voltage 8.5-10v at coil and stud

I am going to replace the distributor rotor today. I still have spark but it’s weak. The voltage is a big problem, and I am sure it’s not the battery. It has to be a connection somewhere. Being that the voltage at the coil And the stud are parallel I don’t think it’s specifically an ignition problem.

I feel that I’ve cleaned the grounds good enough that they aren’t the problem. I would like to trace out the battery cable to the stud. Does anyone know all the connections between the trunk and the firewall for that cable?

It's been quite a while since I stripped my 94 parts car but I THINK the cable goes straight there (not sure if its firewall or under-dash side of that stud)

If you aren't using it yet, the parts catalog may be of some help, check it out here:

https://www.jaguarclassicparts.com/u...nada-usa-parts

Larry

Hi Tony,

Your voltage sag is excessive. Have you confirmed with an ohmmeter that your additional ground cable from the engine to the body is providing a low-resistance ground path? With an engine that won't start it's impossible to do all the voltage drop tests that could be helpful, but as a starting point I would recommend cleaning both ends of the engine ground strap and the battery connections at the starter and alternator (disconnect the battery first).

The battery power connections are identified in the Electrical Guide, which you can download at the link below. Unfortunately, the XJ40 guides do not have the convenient harness diagrams as in later manuals, but the locations of each connection are given on the page before each schematic:

Jaguar XJ40 Electrical Guide 1993-1994

Off the top of my head, on your '94, the connections are:

Battery positive terminal
Battery negative terminal
Battery ground post on rear inner wheel well
Right A-pillar fuse box
Center console fuse box
Left A-pillar fuse box
Firewall, interior, behind airbag (glove box on earlier models)
Firewall jump post, engine bay
Alternator
Starter
Engine ground strap

There are probably a few I've forgotten, but those are main ones. The interior firewall connection is rarely a problem and is difficult to access due to all the stuff that has to be removed or displaced, so worry about the others first.

By the way, please use your User Control Panel to edit your signature and add the year, model and engine of your Jag. The farther your thread gets from your original post the more inconvenient it is for others to have to go back to find the details of your car.

Cheers,

Don

I just had a look at the catalog myself and might be a chance the passenger side fusebox ground stud connects on the way too.

The fuseboxes in these late cars are known to be problematic and quite a lot of us have reflowed the joints by now - not sure if bad connections in the fuseboxes affect the starting though, usually problems involve the ancillary systems like heater blowers etc.

Judging by the description of your car, rust-free and in primo condition I doubt that you have corrosion at the fuse box ground studs, but you never know!

I didn't mention this before as I thought you'd better concentrate on the other stuff first, put the new rotor and cap on before tearing into the fuse boxes!

Larry.

This diagram may be of some help

https://www.jaguarclassicparts.com/u...gement-harness

https://cimg6.ibsrv.net/gimg/www.jag...b8d2f719cb.png

Larry

Larry and Don, thank you very much for the replies! I am very relieved to say that it runs! I put a new distributor rotor on and it fired right up. I was VERY doubtful that was it, the one in the car now measured exactly the same and looked ok. I would say it’s the same brand as the replacement one I purchased. I put it on and reached through the passenger side to start because I had no faith that it was it. When it started up my jaw dropped. Took it for a quick spin down the road, is seems to run good and get to temp and stay there.

The brakes feel feel a little spongey and the anti lock light is on. I do have a ton of more questions, should I start a “build” thread for it or continue to ask here?

thanks a lot for the help everyone!

That's outstanding, Tony! Congratulations on your perseverence!

As far as other threads go, use your best judgement. For something as major as brakes, it might be best to start a thread exclusively on that topic. You could also start a thread on the overall renovation/restoration of the car.

Looking forward to your next update!

Cheers,

Don