Starting problem

[TGNY]

My 66 TR-4A, which for the most part has been extremely reliable has become very hard to start as of late. With a seemingly strong battery, the car won't fire up as if there is no spark. After trying for some time, running the battery low, I hook up a battery charger, and while on fast charge, I can usually get it to finally start. I just put in a new battery thinking it might be depleted but the problem is still there. Cap, wires, plugs, coil, etc. have been recently replaced, though spark appears weak. Is there any specific test for the coil. Anything else I should be looking for. FWIW motor has excellent compression and is used only lightly during the summer months. Thanks in advance.

Edited July 9, 2006 by TGNY

[marvmul]

There are a lot of possibilities of course. Replacing the condensor or trying a spare one, even if it is new is worth trying. Perhaps the points are closing up. Maybe it is the coil, but typically a bad coil does not cause starting problems, but rather misfiring when the engine , and coil, are getting hot. With a TR7 I once had a starter motor with bad isolated windings (more and more of the wires in the coils/windings where shunting : as a result the cranking was rather slow, not very slow, and the car started very badly because the starter motor was drawing so much current, that too little was left for the ignition. Don't know of a specific coil test : resitance in the low voltage coil should be about 2 to 5 ohm (not sure), the spark should be stong/fat (just seeing a spark is not enough), but other thinks can cause a weak spark of course. Swapping a coil of another car is the simplest test I think.

Sometimes strange things can be the cause, like bad earth of the base plate in the distributor, or the wire from the coil to the distributor can be almost broken at some place. It seems that something is wrong in the ignition circuit and perhaps carefully checking the wires and other components will reveal something.

PS : the pin on wich the point is pivoting should be careful isolated from the moving part of the points by the plastic elements : if something of the point or the lead to the point is touching the pin or the nut, you get a short circuit (then you get no sparks between the points when opening by hand, with the ignition on but the engine not running)

Edited July 9, 2006 by marvmul

[Nigel Lay]

I agree with Marvul, try points first - pattern points are notorious for wearing the heal away quickly and closing up which gives the symptons you describe, next the condensor which will give a weak spark. Mind you had a very strange one last year on a friends 3A, it was the HT wire from the coil to the distributor cap. It was one of these 'special' clear low loss types - it had gone almost completely open circuit. When we split it open the carbon filament was missing for nearly 2cms!

Nigel

[Horse]

Agree likely to be the ignition citcuit. Two other possibilities in addition to those mentioned. both of which caused me a similar problems in the past (but not with a TR) which are quick and easy to check:

 

Oil working its way up the distributor shaft and contaminating the insulating washer under the points so that there was a resistive short circuit through the washer to earth. Eventually the engine wouldn't run at all. Check that the washer is clean and dry.

 

A nick in the insulation of the LT lead exposing the wire where it entered the distributor casing (that took a whole 4 days to find, including swapping all the bits and rebuilding the distributor before I found it!).

 

Horse

[Wilfried]

My 66 TR-4A, which for the most part has been extremely reliable has become very hard to start as of late. With a seemingly strong battery, the car won't fire up as if there is no spark. After trying for some time, running the battery low, I hook up a battery charger, and while on fast charge, I can usually get it to finally start. I just put in a new battery thinking it might be depleted but the problem is still there. Cap, wires, plugs, coil, etc. have been recently replaced, though spark appears weak. Is there any specific test for the coil. Anything else I should be looking for. FWIW motor has excellent compression and is used only lightly during the summer months. Thanks in advance.

Once you have established for sure that the problem is in the breaker points-condenser region, I suggest you replace these items with a "Pertronix electronics LU-142 AP12". I bought these from Retro Rockets for $80.-

I have done this in my TR4, on my Morgan+4 (TR3 engine), on a friends MG-TC and all work extremely well. No problems any more with cleaning/adjusting points etc.

 

Once you have established for sure that the problem is in the breaker points-condenser region, I suggest you replace these items with a "Pertronix electronics LU-142 AP12". I bought these from Retro Rockets for $80.-

I have done this in my TR4, on my Morgan+4 (TR3 engine), on a friends MG-TC and all work extremely well. No problems any more with cleaning/adjusting points etc.

[robgeev]

Points.

Adjust or replace.

 

Rob.