Hi All, appreciate a little direction.....car has been sitting for quite a while so have done all the usual...changed fluids, drained tanks, fresh gas and so on. Have checked fuel pump circuit and it is working ok, maintains approx 40 psi in system with no leak down. Checked the injector pulse with niod light and shows nothing....What are next steps from this point? Oh by the way if i mist some gas into the air intakes it will fire but not keep running of course. Also would greatly appreciate if someone has any wiring diagrams to share.

Thanks much, Chuck

 

Lots of 'could be' items.

I'd begin with "the dreaded shielded wire".

Coming off the amp is a thin white wire encased in a heavy-ish sheathing. Inside the sheathing is a braided/woven shielding. This woven shielding is grounded. If the insulation on the thin white breaks the inner strands can short out against the grounded woven shielding. You'll have to open up the outer heat-protection sheathing quite a bit to thoroughly examine things.

This is a 'trigger wire' for the ECU. The injectors won't work without a signal from this wire

Cheers
DD

 

See the attached "S57" wiring guide.

The first section is the for Series III XJ6....but tons of stuff is applicable to your Series III V12 until you get to engine/EFI/emissions

For engine and fuel injection related stuff keep scrolling down to the "XJS thru 1987" section, as the engine & fuel injector wiring is generally the same....although component locations are not.

When you get to the fuel injection sections note there are three diagrams for different configurations. I think page 24.3 might be the closes match for your car

If you scroll too far you'll end up in the "XJS 1988 MY" section


Oops. The file is too big to attach.

Go to the top of this section to the "How to" sticky thread. You can download the S57 from there

Cheers
DD

 

Adding to Dougs words.

The Injector Resistor Pack (Silver box, cigeatte pack size) is usually near the RH side of the radiator panel, inside the engine bay. It has a multi pin plug at the bottom, and is the weak lingk in the Injector Pulse issues with cars that have stood for time. Unplug the thing, take TIME and clean the plug and the mating pins of the pack.

Then the list gets LOOOOOONG.

 

hi Grant, Im looking for the resistor pack you described but do not see anything that looks the size of a cig pack and is silver ?? attached a couple pics of the engine compartment ....only thing i see that is close is the amplifier but it is black. tks chuck

 

It's buried. You gotta dig a lot deeper

It's mounted on RH wall of the engine bay, down low, well forward.

See where the upper radiator panel is bolted to the RH wall of the engine bay? OK. Now look almost straight down. You'll see it.

Cheers
DD

 

ok, on my way to dig....tks Doug!

 

AHA, same place as the XJ-S, thanks Doug.

I moved mine out of the engine bay, loooooong story, but in this snap it is laying on its side, and is a tad bigger than a cigarette packet, obviously a guess from a never smoker.

 

Grant, Doug, wanted to do a quick recap on what I have done on my end. Appreciate further direction in solving this....

fuel pump is working. can hear it when key is turned on, clicks a few times and stops. when direct 12v is applied to pump it runs constant and if you listen at the filler cap you can hear the fuel returning to the tank. I jumped the orange wire to ground and the pump runs constantly when the key is off....not sure about that.

I checked the connections on the resistor pack and cleaned them.
Checked the white wire, opened the sheathing and inspected it and resealed it.

changed the relays, main, fuel just in case (had some good ones )

there is fuel and pressure at the rail but injectors are not firing.
confirmed again by introducing fuel into the air intake....start to fire right away...

help...any ideas?? Tks Chuck

 

Chuck,

Jumping that Orange wire to earth should have the pump running ONLY when the key is in the ON position. If its running when in the OFF position, something is wrong.

Next.

Turn ON the ignition, engine OFF (obviously coz it dont start), NO noise, so you can listen carefully.

Rotate the throttle capstan quickly to WOT (Wide Open Throttle), and you "should" hear the injectors click ONCE.

If you do hear this, the electrical items of the system are doing what they are designed to do.

You then have "stuck" Injectors from standing. They can/will still "click" but NOT pass fuel.

If you hear NO click by doing this, then the TPS (Throttle Position Sensor) located under the throttle capstan is possibly AWOL.

The fact it starts with human induced "whoof juice" indicates stuck injectors to me.

NEXT,

Slide along to the XJS section, and the first "Stickie" at the top is a write up I did for the numerous Non Starting V12 people out there. The S3 is no different, same systems, same procedure.

 

And, just to be sure, still no flickering of your noid light?

If you're not getting any noid light action......

Have you looked at the F.I. grounds? There's a slew of 'em on the RH wall of the engine bay, right about where the diagonal brace attaches to the body of the car.

If you DO have a flickering noid light but the injectors are not working then I agree they are stuck. I went thru that myself. All twelve of 'em !

Cheers
DD

 

Doug, Grant.....double checked the orange wire on fuel pump relay. When I apply ground pump runs with key off and in pos 2, in pos 3 it stops. Also while inspecting the trunk (see pic) I noticed the loopback connector was unplugged. Plugged it back in and tried to start....almost started, was firing on its own but didn't quite start. I am recharging battery and will check tomorrow. One last thing if I pop the neg battery cable off and jump a test light, there is a power drain. Any thoughts on the orange wire and what is that wire in the pic for?? Thanks as always, Chuck

 

Not right. You have a ghost in the machine



Good


Hmmm. Position III is 'start', right? (excuse my brain fade)

I think the pump should also run whenever the starter motor is turning


Odd. Plugged or unplugged it shouldn't matter as far as starting the engine goes. Removing the connector simply allows 'closed loop' operation with the transmission in "P" or "N".


Could well be related to whatever electrical glitch is going on


The one at the f/pump relay? it's a ground wire from the ECU. The CU 'tells' the fuel pump relay to energize via this wire


Which wire?



I think you replaced some relays earlier on, correct? if so, are they exact matches for the originals? The "main" relay is unique in that it has a diode between terminals 86 and 85. The fuel pump relay (and a couple others) is unique in that is has a terminal configuration of 30-85-86-87-87 rather than the much more common 30-85-86-87-87A

Cheers
DD

 

I am as suspect as Doug with those relays.

I am talking XJS now, as my involvement with S3 V12 is one car only, and it has a Wolf 3D engine management system on it, and very different.

When the Ign is switched to #2 = Ignition (idiot lights are ON), bearing in mind that #0 is OFF, and #1 is Accessories, the MAIN relay is activated, and the MAIN relay "turns on" the fuel pump relay, and that activates the fuel pump for the 2 seconds, as per the timer circuit of the ECU, which is the Orange wire.

YES, the Fuel Pump still runs whilst cranking the engine, and therefore the Fuel Pump Relay is ON.

So, by earthing that Orange wire outside the ECU control circuit, simply earths the Fuel Pump relay ALL the time the Ign is ON. If that relay is "live" at other times, the following is my suggestions:

1) Main relay is "stuck" ON, remove the tin cap and clean the burnt contacts, or replace the relay with the spec that Doug has mentioned.

2) The electrical section of the Ignition Switch is AWOL, and this is COMMON due to age.
Easily sorted, remove that section, place the switch in a plastic feezer bag, and open it up CAREFULLY, clean the goop, relube, reassemble, and refit. There is a write up somewhere in here about doing this, but I cannot find it at the moment, but it really is a simple task, and well worth doing, just because.

An outside the square suggestion. Connect a DVM to the +ve terminal of the Ignition Coil, Turn the Ignition to ON (#2), and note the reading, then go to #3, as in cranking (starting to some people), and note the reading again. It will drop a couple of volts, maybe, but a REAL BIG drop indicates that Ignition Switch electrical section having a Lucas moment.

Enough serious stuff.

This will lighten the thread a tad.

Electrical theory as per Joseph Lucas.doc

 

thank you for the input. I am presently cleaning the plugs and checking the injectors....needs to be done anyway. I will check the items you have suggested and report back.
Regards, Chuck

 

Hi Doug. My name is Kent. I have a 1987 XJ6 4.2 Jaguar. No injection pulse and no fuel pump noise. Car cranks but will not start. I have put in a new battery-new-coil- new fuel regulator-new fuel pump-new fuel filter-new relays and clrand the resister pack and cleaned the fuel lines. Still won't start.Where is that thin white wire and the amp on this car.I have to go to the Veterans Hospital twice a week and it is starting to get a little expensive. I need to get my car back on the road. Any helpful suggestions? Thank you.

 

Your 4.2 doesn't have the infamous thin white wire found on the V12s.

The amplifier is mounted on the intake manifold, right at the very front.

On your car the fuel pump circuit operates independently from the rest of the fuel injection system. Here is a checklist to review, post back with any questions

Fuel Pump Circuit Checklist


For no injector pulse there are a couple easy checks to begin with:

1) the bundle of ground wires at the rear of the water rail. Clean and secure? About 5-6 black wires.

2) the white/black wire from the coil "-" post running aft along the water rail. This is the 'trigger' wire to the fuel injection ECU.

Hope this helps, post back if needed

Cheers
DD