I purchased a 1998 Discovery that wouldn't start or even crank to begin with. The day we had it towed home, my dad charged up the battery and played around under the hood all day. The alarm never disarms itself, as it seemed. So he told me to lock it up, and when I did, the headlights flashed a couple times, showing that the alarm armed itself. But we knew it hadn't done that before. So he unlocked it with the key, the alarm disarmed itself and it fired right up.
We go to use it today, and it cranks, but it won't start. It sounds as if its going to start but it just never fires. And when we lock it with the key, the headlights don't flash to show the alarm armed itself, and now the alarm is going off again even though it's supposed to be disarmed. The only difference with this time is that it cranks. I have read spark plugs, but those are good, fuel pump is fine, and CPS is recently replaced.
The only theory I have is that the key fob messed with the alarm system.

Any other insight is appreciated.

 

Inertia switch on fire wall - press top to reset, it breaks power to fuel pump.

RAVE shop manual says your dash LED might be on -

Theft Alarm LED

Slow Flash: Immobilised or immobilised and armed

Rapid Flash: Volumetrically armed

Intermittent Rapid Flash: Perimetrically armed

No Flash for 10 Seconds: Mislock

Continuous: Driver’s door open (or ignition on)
and immobilised

Door switch contacts from driver door lock could also be messed up.

Shop and electrical manual is your friend.

 

Thanks much!
Just replaced the crank positioning sensor, still no spark.
Theory is the immobilizer, very well even the engine module.
Drove it home from work and when I woke up the next day it wouldn't start.
Just cranks and cranks. Ht leads are fine, we can hear the fuel pump working, also read on something called a spider in the alarm system. Pretty much at a trial and error phase right now. Even used the immobilizer bypass code, no luck.

 

I'm having a very very similar issue with my 96. Wondering how you made out? I've always wanted a disco, finally have one and it's really ticking me off! A buddy came over and tested for spark and said it has none!

 

check wires at coil. had the same issue in my d1 would sometimes die and not start back up. mine ended up being a skint wire at the coil making a ground

 

Well it turns out for me that it actually was my crank sensor. We were sold a bad one.
If your check engine light is on, try starting it and see if it goes out. If it does, it's the crank sensor. Running like a dream now. Good luck!

 

That's interesting about the crank sensor, thanks Sig. That's also very interesting about the Theft Alarm LED, thanks Savannah. I always wondered what good that thing was. Maybe that should be a sticky.

 

I replaced the sensor last week thinking that was the problem. It was not. I spent about 3 hours under the hood last night trying to trace power. I have power at the injectors but no power at the coil and obviously spark plugs. I only paid 1100 for the disco and now I'm starting to see why! No anti theft lights are flashing. However I did notice that the doors do not lock or unlock (arm and disarm the alarm) with the key. Wondering what to do next! If I don't figure it out this weekend I'm getting rid of it! Can't put my kids and wife in this disco as a daily car knowing it can and will just die out at one point or another ! Any more suggestions?

 

Like Savannah said, it could be the door switch contacts on driver's door. If you lock it with the fob you should get a slow steady blink from the security LED. Try messing with the fob. I haven't used my key in years. It definitely sounds like a security problem.

 

I agree with DiscoJag. It sounds like what mine was doing to me when I first brought it home. Wish there was a more simple way of completely removing the security system! That seems to be most of the problem in the 90's models. Also, Poolguy, try and lookup if your model has a spider. My '98 does not. But I've read that if the spider in the alarm system/dash is malfunctioning, it can cut your fuel pump or starter.