Same old guys m20 wont fire!!

[Tiger]

Main relay or the fusible link by the battery.

[Lordsneldon]

I am fixing up my mates 525i 1990 m20 and it only turns, it wont fire.

First thing was i swapped out the crank sensor with another - still the same

changed the dizzy cap - still the same

changed the rotor arm - still the same...............

If i test the king lead when turning the engine over, i get a spark on my test probe. If i go to a lead end with my test probe whilst turning the engine over i get a very dim spark.

If I take a plug out and stand it on a good earth whilst cracking the engine i get 1 good blue spark to start with then nothing, just a bit of smoke coming off the plug when engine being turned now and again......I can smell fuel so i know its getting there..... any pointers guys?? cheers

[whiskychaser]

I am fixing up my mates 525i 1990 m20 and it only turns, it wont fire.

First thing was i swapped out the crank sensor with another - still the same

changed the dizzy cap - still the same

changed the rotor arm - still the same...............

If i test the king lead when turning the engine over, i get a spark on my test probe. If i go to a lead end with my test probe whilst turning the engine over i get a very dim spark.

If I take a plug out and stand it on a good earth whilst cracking the engine i get 1 good blue spark to start with then nothing, just a bit of smoke coming off the plug when engine being turned now and again......I can smell fuel so i know its getting there..... any pointers guys?? cheers
I'd check resistance on that 'king lead'. Maybe its duff. Cant see all 6 plug leads going out at once but they are worth a look to eliminate them. Then go for the low tension side of the coil and finally the coil itself. HTH

[Lordsneldon]

Main relay or the fusible link by the battery.

Ive checked the fusable link and its fine!!! what does the main relay look like and where is it?;) ;)

[Lordsneldon]

Yeah, i didnt think that all 6 leads would go down at once, (vitually unheard of!)

I was begining to think along the lines of just replacing the coil......think i'll swap it with a spare and see what happens.

Do you know where abouts the ignition amplifier lives? thought that might be ****ed as well??!!!

[gmannino]

If the compression is shot, the car will only turn over and not fire. If you do not know the history of the car, Id check compression. Since you have fuel, then it must be spark.

[EngPhys09]

Fuel pump? Or clogged Fuel Filter? I just had that issue.

[Tiger]

Black plugs and you didn't mention that? Sounds like you got a major oil leak/burning.

[Lordsneldon]

Right, I put on a new coil.......still wouldnt start????? so i took all the plugs out cleaned them and it started!!!!!!!!!!!! first time.

yes all the plugs were black with carbon, i still dont think that just by cleaning the spark plugs that was the inisial problem, along the way i have changed loads of components.
So i'm pretty sure that as well as the plugs being shitty there was something else faulty that i have already changed??.

Anyway thanks for helping me to resolve:D

[Lordsneldon]

I didnt take them out straight away, because i was getting a very very weak spark to the lead, so didnt think they were the problem to start with.........yeah i reckon the car has an oil problem........but in all honesty the state of the car and the colour of the oil etc, tells me that it hasnt been serviced in years!!!!!!!!!!!!! so i'll give it an oil change quickly and see what happens then.