Good Morning ....
I have been struggling with a problem lately with our 1990 XJ 6 Sovereign...
At first I thought it was a fuel pump .. Pump has power and is operational. Fuel through the filter to the engine. Good spark at the plug. But she still will not fire. Just did a compression test and found all cyls to be within 15 psi of each other ..
If anyone has any suggestions I would surely appreciate some feedback ... I would really like to have this thing running TODAY !!!

Thanks,
The DOBERDEWD

 

I am truly at my witts end on this one ... I really need some help here guys.

 

I'd start by removing the fuel pump fuse or relay and see if you can get the car to run on starting fluid. Be sure to have a fire extinguisher at hand. If it runs on starter fluid then compression, ignition and timing are all OK. If it doesn't run on starter fluid check the ignition with a proper spark tester. An open air visual check for spark isn't enough because spark has to be strong and able to jump a significant gap. If it does run on starting fluid proceed... and get a fuel pressure gauge. You need the proper fuel pressure. Get a noid light to see if the injectors are firing. A $0.99 5v LED from radio shack will also suffice in a pinch just make sure the polarity is right when you use it. Non firing injectors are likely a rotation signal or ECM issue. Poor spark is usually a ignition module. Good luck.

 

A 1990 is most likely an XJ40, if so post your issue in the XJ40 forum too.

 

Ok .... We have verified fuel press at 42 max out of the pump .. Fuel quality good ... no water in fuel.. With a spark tester we have a hot spark of 20k plus volts .. IT WILL NOT START WITH STARTING FLUID OR CARB CLEANER WHEN SPRAYED INTO THE THROTTLE BODY ..
I have double checked timing by bringing it up on compression stroke for #1, vefifying timing marks aligned and rotor pointing to #1 on the cap ..... Comp is at 150-165 ... No coolant in oil or oil in coolant ...
I am going more bald by the minute by pulling my hair out on this one .. that's for sure .... First Jag ... and will probably be my last if I can't solve this one ... No happy birthday for the wife ...

 

So lets see, you say:
1. timing is correct.
2. compression is good.
3. fuel is present (at the rail and throttle body).
4. spark is strong (all plugs tested?) (correct length of plug?).

so either there is no spark in the cylinder (immediate fouling?), or no combustible fuel mixture in the cylinder.

I would try direct injection of starting fluid into the cylinders. hopefully that gets a pop. try to be quick, pull plugs, shoot it in, replace plugs, turn key. Also maybe turn it over a few times when the plugs are out, see what blows out of there.

 

Check the right plug leads are on the right plugs, getting two swapped over will prevent the engine starting.

 

Has anyone removed the dist? Could it be 180 degrees off? You have to make sure you have spark at #1 after the intake valve event on the compression stroke. . On a 4 cycle engine you get TDC on #1 twice. Once after the Intake valve event and once again 180 degrees later. If you're getting the spark 180 degrees out you may get nothing.

 

Ok .... I so feel like a total dumb *** now .... I had others doing most of the work for me and they said that they did this ... this .... and that and here are the results ... I then started to review all of their results .... When I inspected the fuel sample they gave me I started laughing .... Doused myself with it and grabbed my lighter and attempted to light myself up in front of
them ...... It was pure water ......... I pulled the tank, cleaned it out, flushed the lines, installed a new fuel filter and she fired right up ..... Someone yanked the fuel cap and filled the tank with water ....... I think I know who .... Wish they would have left me the cap .. I cannot find one anywhere around here ...
Anyway ... I would like to thank everyone for their input and assistance on this one.
But I still feel like the dumb *** here .... Well like they say .. If you want something done right you have to do it yourself.....
Thanks again everyone ...
The Doberdewd

psss .... Any suggestions on where I can find a fuel cap.? It's a screw on type.

 

I wrote the following before I saw your gas/water solution. Never-the-less this might help down the line.

Me and my 1992 XJ12 just paid 4000 in towing and 1200 in fuel pump and fuel filter issues, nothing helped (stuck in Montana and home in Central Colorado). It had been stopping and then starting with no obvious reason for several hundred miles and then just quit all together. I replaced the fuel pump and filter. It ran for another 100 miles into Yellowstone where it totally quit, again. Turned out that, in Kirby's book on page 361, there is, a description of my issue.
He talks about Injector Resister Connections. I had spark, I had fuel to the top of the injectors, I had everything I guess, except something to burn in the cylinders. If the tiny male plug-ins to the resister box unit are at all fouled or not making contact -ANY OF THEM- the injectors get confused and fail to deliver any gas.
Kirby advises just pulling the plug, taking an Exacto knife and splitting the pins (about the diameter of a healthy tooth pick) just enough to get a tighter connection and cleaning them. I used so emery paper on the surfaces. I also used a tiny screwdriver to scar the female holes. After all the towing and $$$$$$ spent in Montana, she just started up and has been running since, about a week now. A $4000 bill for a ten minute fix.
My V12 has two banks of 6 and the resister box is just right of the radiator and the male plug-in comes up from the bottom. My box of injector resistors has a Lucas label on it though Kirby says that the '92 had a different manufacturer than Lucas for the resisters. Yours probably has 4 pins to my 8. Let me know if this helps.

 

My truck spent 15 years 21 miles from West Yellowstone...they worked on
it many times but had no clue about the CA smog stuff.

When brought back to CA, I found the one connection to the carb had
fallen off and was way lying way behind the carb...it was the total cause of all
the years problems running well in that area...replaced the connector, the
catalytic converter due to running rich all those years and it runs great now.

They also have no clue on AC operations...as well. Got it fixed properly in Covina, CA