MR BFG

MR BFG

Active Member
Hi all,
Land Rover 90 2.5 petrol 1986

After my 90 broke down Wednesday night with no means of starting I had to call the AA out and tow me home. AA man reckoned the issue was a kn*ckered distributor. So I bought a new one yesterday, at first I was getting a nice spark at the points but nothing at the plugs, So I tested the leads resistance and some were quite high (14,000 ohms) so I bought a new set today and some replacement plugs. So I've been tinkering since about 3 o'clock and the spark at the plugs considering there new and with new low resistance leads still isn't great. Thought I'd check the coil and there is barely any resistance between the primary windings (0.4 ohms) and similar result between the secondary.
Also my positive coil wire was connected to the negative terminal and on the coil and negative to positive? I can't see this being correct. Negative earth?

Short answer

Does it sound like the coil is fubar?
And has it been connected wrong all along?
Any other suggestions as to why it won't start?

Rebuilt the Carb last week all new seals, gaskets etc. Also replaced the condenser and it was running fine until it all got foggy on Wednesday.

Cheers,

Lloyd
 
You don't want 'a nice spark' at the points, sounds like the condenser is duff. With regards to lead resistance it is quite usual to get high resistance as many plug caps have a 10K ohms resistors fitted to reduce interference, additionally some spark plugs have built in resistors to reduce interference (normally have an 'R' in the plug type). Ideally you should have resistance in one or the other set ups but not both, i,e resistor plugs on low resistance leads or non resistor plugs on 'high' resistance cables.

0.4 for a primary sounds fine but I would expect a couple of 1000's ohms on the secondary (from the coils HT output to the case or coil -ve terminal) - with ignition off and/or coil disconnected. I don't think reverse polarity coil primary should cause too much difference but why not try swapping them around?
 
Last edited:
Kwakerman said:
You don't want 'a nice spark' at the points, sounds like the condenser is duff. With regards to lead resistance it is quite usual to get high resistance as many plug caps have a 10K ohms resistors fitted to reduce interference, additionally some spark plugs have built in resistors to reduce interference (normally have an 'R' in the plug type). Ideally you should have resistance in one or the other set ups but not both, i,e resistor plugs on low resistance leads or non resistor plugs on 'high' resistance cables.

0.4 for a primary sounds fine but I would expect a couple of 1000's ohms on the secondary (from the coils HT output to the case or coil -ve terminal) - with ignition off and/or coil disconnected. I don't think reverse polarity coil primary should cause too much difference but why not try swapping them around?
Click to expand...


Thanks for the reply.

I have some NGK R plugs that I bought today and the spark from them with these new lower resistance leads looked like something you'd get from an electric lighter. These new leads with normal sparks produced a better spark. I read somewhere regarding the coil polarity that spark plugs don't like If its the wrong way around. I will try and get a new coil tomorrow. Condenser shouldn't be duff as it came with the new dizzy yesterday, that's not saying it isn't. I have a spare couple so I'll bung one on. Any way of testing a condenser?
 
Not being a tabber I'm going from memory about lighter spark size but I would have thought that would be sufficient to start engine if all else is ok (fuel etc)

I believe most condensers have their capacity stamped/printed on them (in micro farads), you wouldl need a meter that can measure capacitance to see if it is correct value but that is not a conclusive test as they can fail under load (big voltage spike from primary coil when points open). Best test is by replacement with known good asset.
 
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Have you checked that you are getting 12v on the +ve terminal of the coil (or -ve in your case if it is connected backwards) with ignition on and that the coil body has good connection to the chassis?
 
I had a reading of 12v yesterday. But now the resistance between the +ve terminal and the king lead is only about 0.3 ohms. But the spark would change when under compression right? So just because it is stronger at air pressure it may be too wiring normal running.

It's just so frustrating it ran fine all the way to Plymouth and after the cinema it started almost instantly. Then only when it hit the really dense fog and I stopped at a junction it cut out and nothing ever since. No warning of the problem.
 
Just another couple of thoughts, have you checked the basics:
1. Are the plugs wet (is it getting fuel through)?
2. Have you checked the cam timing (in case belt has slipped)?
3. You say you have changed dizzy and swapped leads, have you checked HT leads go to correct plugs (firing order)?
4. Is Dizzy / cam / crank timing correct, with No 1 at TDC using crank pulley marks, check the valves are closed by looking at rocker arms (should be loose and fully up) does the rotor arm point at the dizzy cap HT connector that goes to No1 spark plug? It is possible to time some engines 180 degrees out so that the spark is sent to the plug at the top of the exhaust stroke rather than the compression stroke).
 
Last edited:
Kwakerman said:
Just another couple of thoughts, have you checked the basics:
1. Are the plugs wet (is it getting fuel through)?
2. Have you checked the cam timing (in case belt has slipped)?
3. You say you have changed dizzy and swapped leads, have you checked HT leads go to correct plugs (firing order)?
4. Is Dizzy / cam / crank timing correct, with No 1 at TDC using crank pulley marks, check the valves are closed by looking at rocker arms (should be loose and fully up) does the rotor arm point at the dizzy cap HT connector that goes to No1 spark plug? It is possible to time some engines 180 degrees out so that the spark is sent to the plug at the top of the exhaust stroke rather than the compression stroke).
Click to expand...

Plugs are getting wet and exhaust is stinking of fuel after cranking for a while.

Haven't checked cam timing yet, didn't see how it would be driving perfectly then stop one minute, no funny noises just like I had turned the key off.

Yep firing order should be correct as long as its standard firing order 1,3,4,2?

Yep checked dizzy/timing using the rocker arm method multiple times and even checked I hadn't gone to late and was hitting the firing order. Don't think it's possible for it to be 180' out as the shaft only sits in one place.

Just really don't know what else to try. Really want to go tdi but want my little 2.5 petrol to run and being only 17 funds don't allow. Also seems like every rotten disco has migrated out of Devon :confused:
 
It is possible that the dizzy might have been put in 180 deg out, especially on an older engine.
Try swapping the plug leads round 180 deg, and then let us know how you get on.
 
Oldseadog said:
It is possible that the dizzy might have been put in 180 deg out, especially on an older engine.
Try swapping the plug leads round 180 deg, and then let us know how you get on.
Click to expand...

I don't think it's possible on this one mate. I did try swapping it Around 180' and it wouldn't sit in. It looks like the dowel is slightly off centred so t can't be put in wrong. I also timed up the rotor arm with the rocker arms on cylinder no.1

Cheers.
 
1st yes it is important to observe the polarity markings on the coil . also see if you have twin wires to the pos (if yes then you have ballasted system which should feed 12V (nominal) to coil when cranking taking place, and then drop down to lower voltage for running .
2nd Check that your points are assembled correctly , ie with insulation in the correct location. Check setting with dwell meter if available .
3rd Remove centre lead from dizzy cap , and see if you are getting nice fat spark (blue) at each firing point , you should hear a crack .
4th Remove each plug and see if getting spark when cranking ( dont hold plug so you are earth!! ) When removing plugs from engine after cranking see if wet.
5th Put engine on firing point and see which lead rotor arm pointing at.
6th If plugs not wet then its a fuel issue

HTSH
 
tacr2man said:
1st yes it is important to observe the polarity markings on the coil . also see if you have twin wires to the pos (if yes then you have ballasted system which should feed 12V (nominal) to coil when cranking taking place, and then drop down to lower voltage for running .
2nd Check that your points are assembled correctly , ie with insulation in the correct location. Check setting with dwell meter if available .
3rd Remove centre lead from dizzy cap , and see if you are getting nice fat spark (blue) at each firing point , you should hear a crack .
4th Remove each plug and see if getting spark when cranking ( dont hold plug so you are earth!! ) When removing plugs from engine after cranking see if wet.
5th Put engine on firing point and see which lead rotor arm pointing at.
6th If plugs not wet then its a fuel issue

HTSH
Click to expand...

Thanks for the reply mate.

I will make sure I connect the coil up correctly when I get a replacement.

Points should be assembled correctly there is a rubber washer by the screw somewhere I guess this should go between the points and the dizzy body.

I don't quite understand what you mean about the centre lead and getting a spark?

Was getting a spark at the plug when earthed with block etc. but very weak.

I usually turn the crank until the timing marks line up on the pulley and when the rocker arms are both loose of the valves on cylinder 1. In this case the rotor arms points at no.1 Firing point.

Plugs are wet after removing and exhaust stinks of fuel after cranking too.


Cheers,

Lloyd
 
If you go right back to basics:

1/. You should have an insulator between the spring part of the points and the main body, as when the points close they close to earth,
2/. Slacken off the dizzy and take out no 1 plug and, keeping the lead on, put it to earth to see your spark,
3/. Line up your timing indicator on the crank pulley with the valves fully closed on No 1 cylinder,
4/. Turn your ignition on and rotate your dizzy until you get a spark.

You should now have set your static timing.

5/. Nip up the clamp screw on your dizzy, making sure that you can still turn it
6/. Put the plug back in and start your engine,
7/. Time the engine with a strobe light on the pulley ... a chalk mark in both the pointer and the 'v' cut into the pulley will help you to see the marks more easily.

Let me know how you get on. ;) ;)
 
Oldseadog said:
If you go right back to basics:

1/. You should have an insulator between the spring part of the points and the main body, as when the points close they close to earth,
2/. Slacken off the dizzy and take out no 1 plug and, keeping the lead on, put it to earth to see your spark,
3/. Line up your timing indicator on the crank pulley with the valves fully closed on No 1 cylinder,
4/. Turn your ignition on and rotate your dizzy until you get a spark.

You should now have set your static timing.

5/. Nip up the clamp screw on your dizzy, making sure that you can still turn it
6/. Put the plug back in and start your engine,
7/. Time the engine with a strobe light on the pulley ... a chalk mark in both the pointer and the 'v' cut into the pulley will help you to see the marks more easily.

Let me know how you get on. ;) ;)
Click to expand...


Just been out and picked up my new coil, done all the steps above and she fired up lovely. Adjusted the timing til it was running smooth. Taking it for a test drive and she pulls better than ever. Getting a lot more radio interference now though, must be the low resistance leads. Will make it out to the garage and get the carb tuned and the ignition times properly then. Does anybody have the timing for the 2.5 petrol?

Thank you so much oldseadog you really have made my year with that. Hopefully be able to go laning with my cousin tomorrow now. Again, thank you so much!
 
I don't have a timing light so have just timed it so it still runs smooth and doesnt pink. Will have to get it done properly this week though. Thanks again.
 
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