My disco won't start, then a couple days later it starts and runs for a week or two then it won't start again. I got mechanic come to my place and messing around with a relay (plug-unplug) it got it to start again. He measured the pump pressrue its at 30. He says should be around 35-37. Is that true? Anyway I bought a new relay but that did not fix the problem. This morning it won't start again after using it for 2 weeks without problem. Any ideas? Its '99 Disco 1st series. By the way its cranking properly and jump cables don't work.

 

basic premise of an engine is SPARK + FUEL = COMBUSTION.
If one or the other is not present, the engine will not run.

Have you checked for spark and fuel at the engine?

 

Took it to tune-up 6 months ago. Got new plugs and wires, belts. How can I check for spark?

 

So lets start with year, and mileage.
Do you get a check engine light, if so what fault codes?
Check and see if your crank sensor is oil soaked.

 

1999 Discovery 1, V8. 4.0L , 80,000 miles. No engine lights. Need to find location of crank sensor. I am a newbee as far as fixing cars, but I am motivated and fast learner. I have the service manual and I will try to find it.

 

+air +compression

 

touche' nitetrain. but to restrict air or to have no compression without realizing you have bigger problems would be difficult to accomplish...I'd expect.

 

Can't find crank sensor in the manual, is there is another name it goes by? I also remember couple of week ago after filled up at the gas station I started the car and when I was waiting on ramp to get out the idle droped down for about 5 seconds then it when up again.

 

fazekas, might be under crank angle sensor.

unstable, If you have no compression it's likely that your rings have collapsed or you have a stuck vavle...those are pretty big problems. However, I do agree that you should always check fuel and spark before moving on to compression when you have engine problems.

 

fazekas, this webpage shows the guy removing his from the drivers side rear of the block. He says it's a 4.0L but he's working on a D1 so im not sure. Did they put some 4.0L in D1's I thought they all had 3.9L?
http://home.twcny.rr.com/eeibooks/rover/engine.htm