Jaguar Repair: 87 xj6 no start, speedo needle, work bench

Question
I have an 87 xj6 4.2, the only way to get it to start is to advance the ign timing with the distributor. Car was running fine, ran smooth no noticed problems,getting 20s MPG. I stopped to get fuel and shut it off,after fueling it would not restart,towed it home, had spark & fuel, pressure 36psi, played with it and the only way I can get it to start now is cranking in timing advance(clock wise rotation) with the distributor, runs semi ok, reset the ign timing, runs smooth seems fine but when I shut it off it cranks but will not restart, after sitting will crank but no start, now after car has set a few days it is the same, it will only start if I loosen the dist. and advance the timing cold or hot. I got the car about 6 months ago with no power to the fuel pump, pump would not run, I checked every thing over, bumped (taped it on the work bench)the pump relay and it got power to the pump and started but didn't run so good had an intermittent misfire and stumble esp at idle, it died coming to a stop light, and would not start, got it home and had spark, fuel at 36psi but when I brought it to #1 TDC the rotor was not pointing at #1 so I pulled the dist, looked it over didn't notice a problem reinstalled it pointing at #1 and it fired right up, I set the base timing 16deg was the spec I found for it. It ran great, smooth no intermittent miss, no miss at all, and had been that way for the last few months, was low 20s mpgs till the other day when it would not restart after getting fuel. This was why I messed with the dist only this time it was pointing at #1 so I started moving the dist and found if I cranked it quite a bit clockwise it would start right up but ran like it did when I first got the car and got it running. Of interest I have noticed when I turn the ign switch to the crank position the speedo needle will jump and or bounce, and every so often when releasing the ign switch from the crank to the run position the engine will spit, flutter and even may try to back run, but not every or all the time, regardless if I move the dist clock wise it will fire right up. But set at the timing spec it will not

Answer
Hi Glenn,
All that does not tell me what is wrong but I can give you a few things to look at.
First put a test light or volt meter from the negative post on the battery (the post not the cable) and the cam cover and have someone spin the starter. It should not light the test light even dimly and show no voltage.
Next get a known good jumper battery and connect it to your battery as though you had a dead battery even though your battery is up and try to start it.

If neither of these test show anything do the following. Take either a propane torch and open the valve but don't light it. Just spray propane gas into the intake while someone tries to start it. If you don't have a propane torch get a spray can of starter fluid and spray it into the intake while someone tries to start it.

These three tests seem odd but are checks of known odd things about the series III XJ-6 up to the last (1987)
All of the Series III cars require a deep charge battery and even though it will spin fast on a conventional battery or a deep charge battery that has aged, the starter uses up too much of the current for the injection system to operate. Also the Series III cars are notorious for the same problem when the engine is not grounded well enough to the frame. Thus the first two tests.

The third test is because the design of spraying the fuel almost directly on the under side of the intake valve. The valve gets coked up with carbon to a point that the carbon absorbs all of the fuel on a restart and only dribbles into the combustion chamber as raw drops of fuel and does not vaporize well like it is suppose to coming from an injector. Thus the propane or starter fluid test.

If none of this nets you an answer, you need to do the standard tests form scratch, Compression test, check to see that the TDC mark on the front pulley is lined up with TDC of # 1 and 6 (front balancer rubber slips) Check to see that the cold start injector operates (it is not connected to the injection system) (operates off of the front temp censor on the coolant rail) Check injection pulse with a Noid light on the six injectors. Check fuel pump operation by removing the air filter and turn on the ignition and reach in the front of the air flow meter and open the air flow meter door and listen to the pump run. Also check the cam chain tension on the upper chain. If you don't know the history and it has Champion plugs replace them as we could not get much more than 25k on a set of plugs on a ser III at the dealership.

Let me know,
Howard