What can stop a spark getting from the coil to the spark plugs?

My car uses a hall sender in the distributor (with a vacuum advance unit) and an electronic control unit for ignition timing, and I'm wandering if these are fualty. I'm reluctant to just buy them however as they're quite expensive relative to the value of my car! The HT lead from my coil to distibutor creates some nice sparks when held near the cylinder head, but the leads coming from the distributor to the plugs don't. I have a new cap and rotor arm, and new ht leads which I've ensured are not grounding. I've found that the resistance of the primary winding in the coil is below the range recommended in the manual, but seeing as it's creating good sparks anyway I find it hard to believe that's what's wrong. Any ideas?|||If you have a spark at the coil lead but not at the plugs then it must be either rotor arm, dissy cap, or leads.


You say they are new but they could be faulty.


Probably the rotor arm is faulty ( or wrong )|||Sounds obvious but make sure your plugs are clean and gapped correctly.|||You need 3 things to make an engine run: AIR, FUEL, and IGNITION. Check again, you must be missing one of these.|||Check the condenser in the distributor. Also,are you using carbon cord or copper wire HT leads? (carbon cord are subject to random breakdown ) So who thinks (the thumbsdowner) there is no condenser?|||I'm confused...Get back to me... when u take one of the HT leads off one the sparks, does it create a good spark?


And are u sure that the leads on both sides (spark plug and dist cap) are on properly.... push them down again..


i dont actually understand the situation..


From the coil to the dist cap, everything is ok but from the cap to the spark plugs they r not.


Is that what u r saying?|||Inside your distributor cap, on the centre connection is there a carbon brush, or a hole ?





On some early cars the coil lead connection to the rotor arm inside the cap was by a spring loaded carbon brush, its not uncommon for these to drop out.





Hey presto, sparks in, but no sparks out.








EDIT: Alex, what car/engine is this?, have you done anything to the distributor recently, like turn it? or take the rotor spindle out?





I doubt if you will see a spark just by holding a plug cap near the head - have you tried it with a plug in the cap and resting the plug body on some bare metal?





Are you able to check the No.1 cylinder TDC position? if you can. place the engine in No.1 TDC compression, and then follow the HT lead from the No1 plug back to the distributor.





Note where the lead goes into the cap and then remove the cap and see if the rotor arm is pointing to the same position.





Let me know how you get on.|||Are your spark plug wires good? Did you recently purchase this car used from a dealership? From previous experience used car dealers spray a shiny stuff on engine to make it it look good. That stuff messes up spark plug wires and does not allow current to flow to plugs.|||check the fuse for the coil, or pull the power lead off ,and check for power there.