I recently got a 1993 XJS convertible 4.0 motor.. i picked up the car from 400 miles away .. went down and started the car after it sitting for a year. the gas had gone bad and it barely ran at idle but at speed it was better. I put some fuel treatment in it and a full tank of gas and drove it home.. it sat for 2 weeks it started again. took a minute but it did.. then it sat for 2 more weeks and now i cant get it to start..
it turns over and wants to start but wont.

Ideas on what to do ???..

I changed the plugs and will change the fuel filter tonight.. while i have the filter off i will jump the fuel pump and attempt to drain the tank of the fuel that is in there.
1st is that a feasible way to drain the fuel other than removing the tank? if so.. where is fuel pump relay so that i can run the pump safely.,

what else should i check ? is there a way to test the coil
can i back flush the injectors and the rail while i have the filter off??

any help or ideas on what to check would be greatly appreciated

thanks

Bernard

 

Bernard,

I wouldn't drain the tank yet. When you started it the second time, did you take it for a run and fully warm it up? 4.0 XJSs don't like being started and not fully run up to temperature. It overfuels them and can wash the oil out of the rings which makes them difficult to start again.

Try just churning over the starter with your foot flat down on the accelerator for a good 10 seconds. If it then starts to catch, gradually lift your foot off the accelerator.

Worth a try

Good luck

Paul

 

yes let it warm up and took it for a drive. I will give your idea a try ...

thanks

 

Fuel pump, inside that tank, is very high on my suspect list. They LUV (not) sitting in stale fuel.

 

Hi Bernard

Don't overlook the obvious that you may be low on Fuel, as with these In-Tank Fuel Pumps, such as you have on your Car

10 Gallons of Gas will hardly wet the bottom of the Tank and may not even be enough to cover the Sock Filter on the Bottom of the Pump
'Ask me how I know or rather don't'

As for taking the Tank out or even pulling it far enough back in order to Change the Fuel Pump, you really as in 'really really' do not want to go there not unless you absolutely have to as this is such a 'Nightmare Job' that I would rather watch 'Alien' all alone in a darkened room' than to have to do that! (Again!)

As for Fuel Pump Relay, this is in the Boot/Trunk behind a piece of Trim behind the Gas Strut and is also tucked right out of sight underneath the Fender/Wing (inside the Boot/Trunk) where you practically have to stand on your head to see it, where in case you feel like doing that, it is the 'Silver one'

If all else Fails read this:

Changing The In-Tank Fuel Pump on an XJS 4.0L

 

thank you very much for this information .. weather deterred me from working on car hopefully tonight i get to the filter.. I really really don't want to pull the tank so i am doing what i can to avoid it .. running the pump from the relay will help me determine if that is needed ..

as for the fuel level I had put gas into it during the last running before i parked so i think the fuel level should be ok. have noticed that the plugs were a little wet , i have read about over fueling but i will keep that in the back of my mind as i change the filter and pump what fuel is there to see if there is carp in the tank
i will start with the filter, at the same time checking fuel pump.

then decide where to go from there

 

I luv the optimism, and hope the Jag is listening.

At 27 years old, mileage means squat, that pump is on borrowed time.

Sorry to ruin the process, but fact is fact.

The filter renew may give you the Honeymoon period, but a pump change is in your future.

 

thank you .. i hope that you are wrong lol .. I used to work for Jaguar Heaven in Stockton California. as a auto parts puller. so i have taken these cars apart.. its been a while since i worked there but have a good ides of what it will take.

 

So.

I pulled the old filter out (will open it tomorrow and see what the inside looks like ). While I had the line open I had the ignition switch set in the run position and the fuel pump pushed fuel out of the line. In a burst then slowed to a slow stream. Does this sound right ?
I did. Cycle the ignition a few time s to build pressure but still doesn’t start. Seems as if it tries to catch and letting it crank for a while.
I plan on checking the distributor cap and rotor and wires next. I just have a suspicion about the fuel pump. I am not sure if the relay cuts out the due pump or slows it down like that. If you have knowledge on the field pump let me know. Thanks

 

Can you supply the pump with a permanent 12v to test if it runs properly? On the ignition key, the pump will only run for a few seconds unless the car is being cranked or the engine is actually running.

 

Hi Bernhard

From what you've told us so far it sounds like you are getting Fuel, as the Fuel Pump only runs for about 5 seconds at every Actuation of the Key (on/off) ( Normal)

So it is already beginning to sound like it could well be an electrical problem or maybe clogged injectors, in which case you would have to remove the Fuel Rail and clean all the Injectors by blowing them through with Carb Cleaner on a Home Made rig (another fun job to do at this time of the year)

I've got a Thread on how you do that, if it should get to that stage

So the Next Question is, are you getting a Spark?

 

Remember on my Jag, would not start and all the things I tried and then you, Greg, Grant suggested , Crank Position Sensor, I cleaned it and all was well. Maybe same problem here as it has sit so long.

 

Thank you all for your input.

I will definitely be checking Crank Position Sensor as that should rather straight forward thing to check.
I have pulled the plugs and they all seem to have fuel on them. (are wet / maybe fouled) I did hold the throttle to the floor trying to clear the flooding , but no luck. The car previously ran so it has me wondering as stated that something electrical has changed I did try to check the spark,, it did seem a little weak but i know that the way i was testing is not the proper way as i was testing to atmosphere. And I only checked one plug ..
im wondering also if the distributor cap could be bad from sitting for so long.
Being a machinist in real life building rig to test and clean injectors and the rail seems to be something that I could do rather easily and should do since the car sat so long , i will have see what that would look like. Orangeblossom. I will see if i can find your link

again many thanks as I venture into getting this Jag back on the road !!

 

Hi Bernard

Here is the Link to the Rig for Cleaning the Injectors which you should be able to make in about 10 minutes and also a guide to removing the Fuel Rail and taking out the Injectors but don't go throwing the old injector Seals away if you decide to replace them with New ones, as when I did one of the Injectors developed a leak

So I had to then put the Original Seal back on that one though who knows you might just get lucky, also if or when you Clean the Injectors only dab the power on for a Second or you could burn out the Coil inside the Injectors

Though I would start by Testing the Crank Position Sensor, which you can do while its still attached to the Car, once you have unplugged it from its loom, where in case I forget to mention it, the plug is one of those squeeze the Clips together to release it ones, which is also mega awkward to get to and undo

So you might find it easier to unbolt the Bracket with the Plug on like I did

Go in from the Top of the Car, once you have got a visual of where the Plug is and how it locks together, where by way of a bonus you don't even need to remove the Top Hose, the only problem being that even if you did remove that Top hose you cannot see what you are doing, so basically you have to do all this by feel

But once you've got the hang of it then you could change the Crank Sensor by the side of the road if you had to in about 10 Minutes

Testing The Crank Position Sensor (3 different ways)

(1) Crank the Engine over while watching the Tacho: If the Tacho Needle Flickers then the Crank Position Sensor 'May be ok' (as that is a good indication)

(2) Undo the Plug on the Crank Position Sensor and connect your Meter to the Pins that go to the Crank Position Sensor (there are only 2 pins) and set your Meter to Ohms 2K you are looking for any kind of resistance 800/900K if that checks out the Crank Position Sensor 'may be ok'

(3) Connect the Meter to the Crank Position Sensor Set the Meter to Volts (MIND YOUR FINGERS!) and Crank the Engine over and you should get a reading of around 20 to 28 Volts if so then the Crank Sensor 'Should be OK'

Your No Start Problem could also be caused by a Faulty Ignition Switch, so what you could do to Test that is to Connect a Wire direct from the Battery+ to the Positive Terminal on the Coil and then Crank her over and see if She will Start (if She does then you'll know its the Switch)

Also just down by the Passenger Knee Pad are a number of Fuses under the Cover and one of those is the Fuse for the ECU there is a diagram inside the Cover so you should find it OK I think its a 10 amp one on the Top Row Check it very Carefully in case it is corroded or looks like its on the way out

Also above these Fuses are Two Blue Relays in Holders, where the Blades are known to sometimes be a bit thin compared to other makes, so it could be very well worthwhile to take them out of their holders and re-seat them as if they don't make good contact, then your Car may not Start

Good Luck and here are the Links

Removing The Fuel Rail and The Injectors to Clean them using a Simple Home Made Rig

Removing The Crank Position Sensor on a 4.0L AJ16 Engine

 

Did you get a chance to look at the fuel that came out of the line when you changed the filter?
If the fuel was dirty or contaminated with water it might have shown up there.
That vintage tank is not prone to rust unless there is moisture accumulation.
You can Jump the fuel pump by disconnecting the plug from the harness in the boot.
Have you listened for the injectors clicking?
I would do an inspection and test of all the injectors before messing with the CPS.
The most likely failure of a CPS is debris in the gap.
Where in CA are you?
I'm in Pacifica.

 

Orangeblossom thank you for the link lots of info going on there will refer to it as needed

Equiprx I am in the Central Valley Fresno area i did look at it it looked pretty clean didn't notice debris
not sure if i have heard the injectors clicking will pay attention to that in future attempts to start the car..

 

here is the filter




Mounting in lathe with center

Positioning cut off tool

Opened !!

Apart !

Not perfect. What do you think. No large chunks in the filter. No rusty bits

 

Hi Bernard

Skilful piece of Machining there and looks like the Filter was doing its job, although its either blocked Injectors or the CPS as well as anything else I mentioned in those threads I sent you

Also do not overlook the Cut Out Switch on the Passenger Side near the door hinge in that little plastic box, which may need the button in the hole in the Top pushing down and resetting, in case it has jumped out

Alex

 

After viewing your posts i decide i should photo document as much as i can

 

Hi Bernard

Help yourself (lol) but there is only a limited number of things that it could be, so hopefully we can get there in the end

If none of that works then it could also be water getting into the Plug of the ECU which is down by the passenger foot well although it is much more likely to be in the areas we have been talking about

CPS or Blocked Injectors 'Prime Suspects'