6 replies to this topic

[Tommyboy12]

Bear with me here. Got a 998 Pre-A+ engine in my Jiffy project with a 25D. The wiring is not complete but ive been trying to get the engine to start before I introduce the rest of the wiring loom and things get more complicated.

 

It’s a non-ballast ignition. Currently I have the + coil hooked to 12V battery, - coil to dizzy, earth through the dizzy/engine to the battery via an earth strap. The coil, cap, points, condenser, and HT leads are all new. Ive also replaced the 25D with a cleaner example as the original had rotten weight springs that couldn’t hold any tension and plenty of other corrosion. Ive followed the troubleshoot in the Haynes manual to the letter and get the following results.

 

Battery reads 12.5V

No spark from spark plugs to block

No spark from coil HT lead to block

+ coil to earth 11.9V

- coil to earth 0.4V (points open) – The Haynes manual says a ‘reading’ means the system is fine but this seems low and the manual doesn’t specify a value?

No reading between moving points and earth with condenser disconnected

The – coil to dizzy cable is new and not broken

The coil gets hot when the engine is cranked

Points gap is set to 0.4mm as per manual

 

Ive tried multiple coils, points and condensers to no avail. Still no spark. The coil isn’t mounted to the engine but I don’t believe that makes a difference? Also, the distributor arm is rotating before anyone asks!

 

Any advice? Thanks.

Edited by Tommyboy12, 13 July 2015 - 11:39 AM.

[dklawson]

The coil, cap, points, condenser, and HT leads are all new.

 

+ coil to earth 11.9V

- coil to earth 0.4V (points open) – The Haynes manual says a ‘reading’ means the system is fine but this seems low and the manual doesn’t specify a value?

 

As the ignition parts are new, I suspect the issue is with the points.  25D points are finicky regarding the placement of the nylon bushing/spacers.  Your voltage measurements suggest this is the problem.  With the points open, coil (-) should read the same 11.9V as you measured on coil (+).

 

Refer to the picture linked below and re-examine the points you installed.  Note that no metal parts of the moving points arm/spring, condenser wiring, or distributor wire should touch the threaded post on the points base plate.  

 

[Tommyboy12]

Sounds like this might be my issue as I dont specifically remember doing this. Ill check the system tonight. Will this shorting through the points cause any damage to the condenser? I have spares if its likely junked them.

[dklawson]

No damage will happen to the points or condenser if the insulators are on in the wrong order.  The only bad thing that can happen is if you leave the ignition on for a long while you could burn up the coil.  I know you said yours was "hot" but it would have to be hot for a long time to damage it.  Coils run warm anyway.

[carbon]

+1 for Doug's suggestions.

 

The ignition coil should not be getting hot when just cranking over the engine, in my experience putting full 12V through Lucas LA12 coil which is typically used with 25D dizzy should take 15 minutes or more before it gets hot.

 

Would be worth checking the resistance of the coils you are using, for a non-ballast system should be reading more than 3 ohms when cold.

[Tommyboy12]

You were spot on Doug. I had the condenser and coil wire above the nylon spacer at the top. Swapped them round and it spluttered almost instantly into life! Now I can sort the timing and fuelling.

[dklawson]

I am glad it started.

 

Thanks for posting your findings.