Intermittent no start

[JeffDB]

I’m having a weird intermittent starting issue. It began with hard starting having to floor accelerator to get XJ to start progressing to barely cranking over and not even getting a jump from tow truck to turn it over. My tech said bad battery cell. Bought battery 6 months ago. Take back to place I bought it for test. 1200 cold cranking amps. Store gave me post shims. Put them in and reconnected battery. BANG! Started right up! For 3 days. Then the whole hard start pedal to floor thing started again until no start. Let XJ sit for 3 days. Tried again and BANG! Popped right off! What’s going on? Has a demon possessed my XJ?

 

[Anak]

What is the condition of your battery cables? If they have not been upgraded that is where I would begin.

Next up would be starter and solenoid.

The one thing I do not understand at all is the effect of the accelerator pedal. What year/engine do you have?

 

[rtd16]

I'm coincidentally having a similar problem on a 1993 XJ Sport. Did you get yours resolved? Mine isn't to the point of not starting, but intermittently (I'd say every 3 out of 5 or 6 starting attempts) will sound like the engine is struggling to turnover (almost like the battery is dead), and when it does fire it idles rough for a minute before it smooths out, but also has a noticeable lack of power when driving. If I shut it off and get it to start normally, it idles and drives fine. I had the alternator, battery and starter all tested and they were good (starter is also new). Fuel pressure is good, cleaned up the ballast connectors, and tested it on a different ignition coil with no luck. I can't for the life of me figure this out.

I think I know what you mean with the accelerator - during the hard starts if i don't touch the accelerator it seems like it won't bark off. But if I pump it while it's happening it will. I agree Anak it doesn't make sense to me either.