My 90 VDP 86k wouldn't start last week. I changed the fuel pump, I have lightning sparks as well. My question is this. Can you have spark and still have a bad crank position sensor? Remember this car sat for 6-7 years before I bought it, and it took me forever to get it started back in Dec 2010. As I recall, I did have spark. I pulled a CPS from a junker and the car was great until last Monday. My suspicion is that CPS...again.

 

In a word YEP.

On the AJ6 engine you can, the AJ16, NO.

 

Thanks Grant, I'll go get another and keep you posted.

 

CPS shows 1.4 on the OHM meter, that's not the issue. Replaced filter, and fuel pump. I ordered a distributor and rotor. I will continue to diagnose

 

Remeber the triangle.

Air, Fire, Fuel.

If your getting air and fire (spark) then its the fuel.

If shes turning over and not starting Id look at the pump first, and work forwards from there.
You already replace the pump and filter. Have you confirmed that the injectors are fireing?.

You can easily confirm the dist and rotor by unhooking one of the leads from a sparkplug, and hold it in your fingers. Then have someone try to start the car. IF you get a sharp shock, you can bet the plugs are getting fire! (this was a way I mistakenly did it. My intention was to watch the spark plug fire but my helper was a littler too enthusiastic and turned the key too soon. lol)

 

lol. No thank you. This issue has me chasing like a dog. I bought one of those spark testers that plugs into the spark wire, then you ground the other end, you can even measure spark. I was able to set it up so I could see it when i was in the car. No spark. I replaced the coil, still no spark. I replaced the CPS, distributor cap and rotor, no spark. Yes I did put another pump, new filter and fuel regulator on the car. I have voltage going to the ignition amplifier. I have gone out this morning and got another amplifier, coil and yet another CPS, actually this CPS shows a much higher reading on the meter. I bought a brand new rotor and distributor cap as well. As soon as I get the energy, i will go and replace everything again.

 

mrtalkradio,

Instead of bouncing back and forth between threads, I've decided to respond to your prior post here, on your thread.

Lest I forget (everyone knows #1 but I'm just checking),

1. did you check to see that the Inertia Switch is NOT tripped? (I don't know what all this switch kills on a 90MY)
2. did you test for a good coolant temperature sensor and connection?

The following tests I suggest are similar to what I posted on pink_chilli's thread, Ignition Issue, although that was an 89MY and the wiring diagrams I posted there differ from your car.

th_1990VDPCrankSensor-schem.png?t=1315671067

(click thumbnail to see 90MY Crank Sensor schematic)

Dynamic crank position sensor test

Crankshaft sensor wires, R (red) and U (blue), connect to the LOW POWER ECU at pins LI59-13 and LI59-24.

1. Find your ECUs,
2. locate the LOW POWER ECU,
3. locate the afore mentioned pins,
4. connect the probes of a voltmeter set on the AC function to these pins,
5. have someone crank the engine, and
6. check to see if you are getting a pulsed signal.

If you don't, something is wrong with

• the wiring from the ECU to sensor connector,
• the gap between sensor and gear teeth (should be 0.018 to 0.042 inch) or
• the Crank Sensor itself.

If you do get a pulsed signal, then its time to check for proper ECU - Amplifier - Coil operation.

I'm reminding myself here that you should find the WB wire (white/black tracer) connecting the amplifier to the coil, connect a voltmeter to the coil at its negative (-) terminal end and ground, set the scale to AC volts, have someone crank the engine and check to see if you are getting a fluctuating signal. You most probably are not.

The amplifier acts as a switch, periodically shunting the coil to ground. The capacitor is provided to smooth out the transients (or spikes) in coil's voltage waveform.

o

 

Thanks for taking the time to post/re-post. I read all your stuff. I brought a ECU and CPS and Coil from a working vehicle today. Still no spark. I did see a pulsating light from the neg terminal on the coil while trying to start the car. No spark from the center of the coil. This is my third coil. The ecu is from a working car. I still can't get this started. It tries with starter fluid. I am frustrated. Fuel pump, filter, dis and rotor, 3 coils, 3 CPS, 2 Oxygen sensors, fuel regulator and a ECU. I have voltage to the amp, and to the coil. You would think it would be the coil, having no spark from the center of the coil. I can understand having 2 bad coils, but the third was from a running car.

 

"Curiouser and curiouser", said Alice.

Hmmm ... It reads to me that your primary winding of your coil is getting juice and that circuit is pulsing.

Now it seems there is something wrong with your secondary circuit.

It's odd to read the secondary (high resistance) wiring of the coil goes through the primary winding to ground, but that seems how Haynes explains to test it.

1. There is a B (Black) wire coming from the amplifier terminal LI28 that connects directly to the ground, LIG30. I don't know where this is located, so you'll have to trace it back from terminal LI28.

There are 3 other connections to this ground: a diagnostic socket terminal, the shield surrounding the crank sensor and oxygen sensor, and more disturbingly, pin LI58-24 of the HIGH POWER end of your Engine Management ECU.

Ensure this LIG30 is a good ground. Of course, all grounds are important - they constitute 1/2 of your car's wiring.

2. I've searched and found no mention of your replacing sparking plug wires and more importantly, the coil to distributor cap wire. Could yours be defective (a possible break in it)?


still from Tim Burton's Alice in Wonderland

o

 

All grounds are clean and well grounded. Wire from center of coil to distributor ohms out. I have 3 coils, all three's center coil looks good. They ohm at at almost 8 when checking it. This certainly has me totally bewildered.

 

• I am still suspicious of the high tension lead between coil and distributor cap. I've known them to "open" internally if you bend them just right.
• Is your GROUND good between the engine block and -tive battery terminal?

th_1990VDPIgnCoil-Amp-ECUschem.jpg?t=1315671067 (clickable thumbnail)

I would isolate the coil and try the following. See above schematic before reading the following.

Dynamic (on car) Coil Test

1. Turn ignition key to the off position and remove it.
2. Disconnect the 2 WB wires from LI27, the -tive terminal of coil.
3. Disconnect the WK wire to the amplifier from the coil and put some electrical tape on the disconnected end. Do not allow it to touch GROUND.
4. Maybe for now even disconnect the capacitor end connected to LI26, the +tive coil terminal. Keep WK wire connected to coil.
5. Connect a NEW wire from the -tive terminal of the coil and connect it either to a good ground or better still to the -tive battery terminal.
6. Remove the coil to dist cap h.t. lead at the dist cap end and connect your spark plug tester to this end. Connect spark tester clamp to a good ground.
7. Have an assistant turn the ign key to the on, but not the start position. There should be 12V at coil terminal LI26 every time the key is turned on. There should be a spark jump across the gap of the tester every time the key is turned off.

• Naturally, if you have a spare switch, you could wire it to the +tive coil terminal and connect the harness WK wire to it. This way you don't need an assistant. You can just turn the ign key on and energize/de-energize the coil from the remote switch.

• If you do it this way you've reduced the risk of getting shocked from high voltage because you are pretty much isolated from the secondary. If you have rubber gloves, wear them anyway just in case there is something wrong with the coil.

o

 

Thank you. I will do what you have described. I do have a pulsing light from the negative side of the coil while the engine is being cranked. Its dim but its there. My battery is taking a charge now, it has taken a beating the last week or so.

 

Here we go. Thanks again trick for your input. 2 issues I have had. There was intermittent spark. The tests I did, from your posts all showed voltage. I have, somehow regained spark, like lightning as well. Hurricane Irene came in on a Sunday, it was Monday the car wouldn't start, after weeks of replacing everything 3 times, it appears there was at least 10 gallons of water in the tank. I removed it all, got the car to start and run smoothly. She stalled. I continued at least another 30 minutes with starter fluid, and cranking. No spark again. While it was running I was able to pull a code 24. Ignition ECU Amp issue. I went back in to try another coil, when the little wire from the capacitor came out. So I will go and get another tomorrow. How did the water get in? The little hole that drains the water was plugged up. When I opened the cover the water was to the top above the cap, I assume it got in through an air vent somewhere in the cap. I actually cleaned that out 3 weeks ago monday, it never occured to me water could get in the tank from there. Clear out that little hole in the rubber that surrounds the cap folks. After i get a new capacitor, the car by all right should start. I'll be sure to let you know tomorrow

 

If you have followed along these threads about cranking no start, cps etc..then you surely dread if it ever happens to you. 2 Fuel pumps, new filter, new regulator, 5 Used But Working CPS's, 4 Working Coils, 3 used but working amplifiers, 1 Working ECU, 5 Brand New Relays. I drained between 12 and 14 gallons of fouled gas/water. No spark still. My last post was last Thursday or Friday, basically waving the white flag and ready to burn it.
Today I finally said I will have it towed 30+ miles to a friend of mine, that can do more than I. Its been 4 weeks as of yesterday this car will not start. 93$ tow fee. The car got there at 10:09a NY Time this morning. My friend called me at 10:23 and said, "car started right up." He has had it all day, it is now 7:41p, he started it all day. His last text to me 35 minutes ago was simple. It said, "car is running flawlessly." They say there is a reason for everything, I am so anxious to find out the reason for this episode!

 

Well bloody done.

It just wanted a ride on a tow truck hahahaha.

In ALL my years with Jaguar, I established loooooong ago that ALL Jaguars are female (you work that one out), and must be treated as such.

My XJ40 3.6ltr was "high maintenence" and we soon parted company.

 

Faulty CPS

 

Heh I had my car towed 85 miles and went carless for a week because my boot hit the inertia switch and tripped it. Never would have guessed if I hadn't just happened to open my Haynes to the Inertia Switch test page that made me go "hmm can't be, but it's an easy check..."

 

I am at it again with this black 90 vdp. I am not so sure the problems we have addressed above were my issue. I hate making these posts long, but as much information I can give can help me finally resolve this ongoing issue. I remember while tackling all the above troubleshooting suggestions, that at one point the fuel stopped pumping out of the rail and the fuel pump just stopped. Cut to the chase, it is an ongoing issue and causes this vehicle to stall out and not restart. I have 2 fuel pumps that both work while bench testing. I also have 12 volts at the connectors that attach to the pump when you first turn the key, it is for a split second. That is what you hear when you turn the key. This is where I am stalled. I do not hear that fuel pump at the turn of the key. Either one of them. And they both work, and I am getting voltage to those pumps. Where else may I look next. I changed out the relay with a known working one as well. Any help, of course would be appreciated.

 

Mmmmm, not sure about the '40, but our earlier cars had the "earth" of the fuel pump relay controlled/triggered by the ECU, and the 6CU was a mongrel for fuel pump control circuit issues, haha, teh 16CU was better, of course that is the V12's, but all systems are basically identical.

You have 12v TO the pump, OK, got that, and the EARTH of that relay is controlled by the ECU, hence the timer effect we all know of.

I would by-pass that relay, which removes the relay and ECU from fuel pump control. BE BLOODY CAREFUL, coz when by-passed the pump will run at ALL times the ignition is ON, and NO enertia safety etc is operational.

If that fixes it, the ECU is suspect, OR the signal from the engine to inform the ECU that there is ignition activity, so pump operation is required. Where that comes from, NO IDEA on a '40, sorry.

 

Thanks Grant,

So if I take out the relay the pump will run all the time? If that is the case, I should be able to diagnose that issue pretty easily?.