So frustrated.... About to call the junk yard. No spark after starter

Team XJS,
I am beyond frustrated at this point. I have spent a buttload on new parts and am about to call it quits. Willing to give one last try with your help.
I finally got spark after replacing both crank sensors. THEN… while trying to start the car. My starter took a dump… Ordered and installed gear reduction starter from british starters .com
After installation… No spark and no injector pulse yet again.

I know the battery positive and the alternator has a harness that attaches to starter. The other is for the starter solenoid. Starter seems to work fine. BUT… Nothing else has changed from before I put the starter in. Is there anything that could be connected improperly? I really need help her team…

Wanted to add that in order to install this starter the positive feed and alternator harness required light tugs. But again… every light on dash works and cranks fine.

Injector pulse depends on spark, so your problem is spark. Try trading the ign amps.

If starter is turning over motor, then you hooked up starter fine.

No spark, you’ll have to investigate ignition. Coils? Plug wires? Distributor cap/rotor?

Coils are new, Wires, cap, rotor, plugs and cam and crank sensors. I have power to coils with key on. Just lacking pulse and spark. I have looked and don’t see any wires or anything out of sorts. Does the wiring to the alternator have any correlation? I gave them a decent yank to attach to new starter.
Is there a way to test the ignition amps?

Does anyone have a diagnostic flow chart I can follow?

Forgot to add… Fuel pump comes on when ignition is turned on. Verified fuel at rail

I’m not too familiar with post-Lucas V12s, so should probably bow out on advice.
Though the big positive cable to alternator shouldn’t make any difference, but i have no idea if there are other connections to alternator or starter that may have got disconnected when you pulled?

But don’t give up. These cars are a try in patience for sure!

About the time you would junk it …the junkman will spend two bits and make it run and sell for 100 times what he gave… Sleep on it… the answer will come.

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Don’t give up. On a Marelli car with these symptoms there’s a very high percentage chance that you are not getting a signal all the way through from the crank sensor at the harmonic balancer or the engine speed sensor at the fly wheel…

Both of those sensors have to send a signal to the Marelli ECU in the right side passenger foot well.

Then Marelli ECU has to send a signal to the Lucas ECU in the boot via the legendary white coaxial wire that runs forward from the Marelli ECU into the engine compartment along the left side of the fuel rail, makes a. U turn, then goes back to the boot to meet the Lucas ECU. You read that right, the white coaxial wire connects to nothing in the engine compartment. It’s just an oddity of the wiring harness that resulted from the switch from the Lucas to the Marelli ignition.

Since you are not getting injector pulse or spark, the crank position sensor and the engine speed sensor signals are suspect.

Having said that, I would swear on a stack of Sears catalogs that on my car the white coaxial wire being interrupted results in the same symptoms, but as I write this I can’t square that in my brain, seems like you’d get a spark but no injector.

Bottom line, on a Marelli car with no spark and no injector pulse check the obvious first. Make sure that your crank sensor, engine speed sensor and white coaxial wire, are all doing what they’re supposed to. Visual inspection and ohm meter are ok, but Unfortunately, per the ROM, the only way you can be 100% sure, is with an oscilloscope. Fortunately, you can buy an oscilloscope for 100 bucks that will tell you this.

Sure, it could be something else, but if this were me, I would check those three things first.

Keep the faith!


Great News to share… IT RUNS!!!
I double checked all connections and found the amplifier connectors to be corroded. Cleaned and the beast fired right up! Thank you all for convincing me to not give up.

Now that it is running, idle was very high… about 2k rpm. Then once warmed up, idle is unstable. Seems like car is hitting fuel cut or something. Idle goes up and down like someone shut off and restarted. I have to chase vacuum leaks and reset EVERYTHING. AAV screw is still way out. Can that cause this issue?

One other request… Does anyone have a good pic of the PCV line from breather to PCV into air box? Need to see what I am missing.

I still have the air pump and also need pics of the line from valve that appears to go under the intake. metal line with what appears to be a collar.

Thank you again!

Thank you again.


Yes it could, as this is the way you adjust the idle…

Hello Roland - try this for pics and part numbers for the crankcase breather pipes and PCV filter - go to - then follow drop-down menu - XJS Sports Coupe Convertible - 1975 - 1996 Classic - XJS from V 139052 up to V 179736 - Engine Management - Emission Systems - Crankcase Control System - this should get you the two parts drawings, along with the part numbers.

maybe these will help… its a little crowded right in that spot…

**for what it’s worth…my idle was erattic so i by-passed aav…,. Later found many vacuum lines were loose fitting… Replaced them and back to using aav again… high idle can be from too much air sucking into engine

Thank you TEAM!!

I looked at the diagrams and am a little confused by something. Looking at them, it appears the pcv goes directly into the air cleaner housing from the balance pipe. Looking at my car and the pic from Pirk. I must be missing something. The pipe off the breather goes somewhere that I can not ascertain. Must be something the pipe attaches to and maybe tees off to balance pipe and then into air cleaner box. Can anyone assist?

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THAT IS PERFECT! Just for clarification. I can see the TEE off the balance pipe. Where does the hose go that passes the oil cap?
I see where the breather hose goes into ?? Is that your air cleaner with pcv into it?

The hose that runs past the oil filler cap goes underneath the air cleaner snorkel and connects into this vacuum valve. It comes in where the two hose clamps are close together, I must have a reducer in there of some sort.

The vacuum valve has a big hose that comes out of it that goes down into the charcoal canister in the fender well, I am not sure of the exact connection there, there’s a lot going on down there. The small vacuum line coming out of the vacuum valve goes to direct manifold vacuum.

Yes, that is the PVC plugged directly into the back of the air cleaner. You can see it here i’m pointing to it.

Not sure if you have the stickers or if they are helpful in this case, but here they are.

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Yahoo. Large step forward. It runs. Now to chase down and fix the irregular idle.

Decades ago, I got mad at out 58 Pontiac Star Chief. Not completely enamored with it. I got it cheap and it was clean, comfortable and fast.

Then it began to have starting issues. worse and worse. got mad after many efforts to find and fix.
Off to the junk yard. SOG, months later, I saw it on the street!!! In cooler time, I think I got it. Jumped timing chain. Not an easy fix, but DIY doable. .

I have made great progress! Feeling pretty good right now! Thank you for the support.

Few questions and I will be back at it…
Looked at the vacuum diagram but can find my answer on this. Passenger/right side intake has a vacuum line underneath. Where does that attach?
Also, from back of air pump, there is an s shaped pipe with a coupler looking piece. Can’t figure out where that attaches.

Thanks again!

Clarification on intake vacuum… It is behind the throttle body, underneath