Electrical starting problem!

[Rubce]

Evening All

After covering 1,400 miles last week on our Scottish trip without any issues our Stag has decided to act up now she is home in her dry garage! After standing un-used in the garage on Monday I jumped in her yesterday morning for the drive to work. Put the key in the ignition, the instrumention and fuel pump came to life. I then turned the key to final stage to start the engine and everything went off. There was no sound from the starter and the engine did not try to turn. I switched the ignition off and tried again with the same result. On the third attempt the instrumentation went dead and would not come on again when I turned the key. So, I shut the garage door and used the Volvo.

Fast forward to this evening. I checked the security of the battery terminals and the main cable to the starter. I checked that the headlights, wipers, indicators etc all work so it appears to be isolated to the ignition/starter circuit. I tried to start the car and again the pump, instrumentation and lights all went dead. Upon trying a final time the starter solenoid clicked several times before everything died.

I checked the voltage across the battery terminals with my multimeter and got a reading of 12.24 volts which seems a bit on the low side tome as I seem to remember that it should be giving 13+ volts? However, surely even with 12.4v it would have enough get up and go to crank the engine over slowly? I think I will connect up the trickle charger to it tomorrow to see if that helps.

Any suggestions?

Thanks

Bruce

[Staggard]

I know you have tried but to me sounds like battery terminals, did you take them off and clean up the posts and the terms.

[stagwingnut]

Try cleaning the multi plug contacts at the rear right hand side of the engine ,near the brake pipes at the bulkhead above the starter motor , as u know is the starter circuit connection to the ignition switch , regards Graham

[KOY 23]

Check voltage across battery when trying to crank. If it stays around 12v you have a high resistance in main feed or earth. If it drops way down it's probably the battery. Could also be the starter motor but not so likely.

[marshman]

Bruce, what happens if you turn the headlights on then try to start the car? If they stay on then there is a high resistance somewhere in the positive ignition feed, the current demanded by the starter solenoid causes a massive volts drop across the offending fault point, (fuse box? If the feed is fused.) If the headlights are ok on their own its unlikly to be the battery or terminals in my opinion. You won't usually see above 13v on a battery unless it has just come off charge.
Roger

[Ian F]

Bruce

Agree with Staggard, re-check terminals but also check and clean/tighten earth strap, it may have come loose over those testing Scottish roads?

ian

[Bob Heritage]

Had a similar problem out of the blue recently, new battery cured it. Check earth leads first though.

[mallardstag]

A loose & corroded engine earth strap caused the same symptoms on mine. Check this first otherwise the starter current returns via the choke and throttle cables which both had to be replaced as they burnt internally.

[Staggard]

The earth strap from the battery has two grounding points body ,engine. when the key is turned it appears to break connection to everything. My way of thinking is if it was just the starter and engine electrics then we can blame the engine earth contact likewise if we lost lights.wipers, ect then we can blame the body contact. but both together possible but unlikely. So working backwards leads to the battery or the contact between the posts and the terminals We will see.

[marshman]

My thinking was that in the first part of his post Bruce said that there was no noise from the starter - not even a click from the solenoid so the starter could not be drawing current, only the solenoid. The solenoid does draw a high initial current as it kicks in which would "test" any poor connection in either the earth or somewhere along the positive feed. If he tries it with the lights on and they stay on without dimming then as I said the fault is unlikely to be with the battery or its terminals. I ruled out the engine earth connection in my mind as this wouldn't/shouldn't affect the pump and warning lights. Always difficult to diagnose at a distance but if the lights remain on then my money is still on a fault in the positive feed to the ignition.

Roger

[Rubce]

Hi All

Thanks for all the useful suggestions I had opportunity to look at the car again this afternoon. Those of you that followed my restoration thread back in 2008 to 2010 might remember that I assembled my own wiring harness. There is a main junction box adjacent to the battery with three terminal studs. When I got a firm hold of the cables I discovered that one of the retaining nuts was slightly loose. That particular nut secured the main feed cable to the starter. Tightened it up and hey presto the car lives. To prevent a reoccurrence I have fitted an additional locknut to each of the three terminal studs.

Thanks again for all the assistance. It is one of the things that makes this forum great.

Regards

Bruce

[Robin Searle]

These were the closest threads to my 'starter/ignition switch' mystery that I am and have been for some time experiencing so here goes.When I go to start my 73 Stag and turn the key it seems as if it will only start at the end of the turn and just when I am about to turn off and start again.The starter motor was replaced three years ago and the ignition switch a brand new NOS Lucas one a week ago,when having my steering column rebuilt,but lo and behold when starting her again same idiosyncrasy at the end just as I am about to turn the key off.

Any help from all those experts in Stag land??

Robin

[V Mad]

Robin
Put a volt tester on the coil + then turn to the start position. You may find that the coil is only getting a supply when starter is released.

[Tdm]

This is not offering a solution to either of the above problems, one of which appears to have been resolved, but about a problem I occasionally experience when starting my Stag. About once in every 50 starts I turn the key and nothing at all happens - not a sound nor any "click" from the starter motor (which is a high torque one from Rimmers bought about 8 years ago).

I now know what I have to do - which is open the boot and retrieve the crow bar I keep in there for such occasions, then open the bonnet and using the crow bar give the top of the starter motor a quick strong tap with it.

That usually does the trick and I think the reason is every now and again the teeth on the starter motor and the flywheel don't quite mesh, possibly due to a single worn tooth on the flywheel as it happened with the old starter motor also. If I ever get stopped by the local Police and have to open my boot I doubt if they will believe me when I tell them the reason I always carry a crowbar and a big hammer in there!

[Pirate]

These were the closest threads to my 'starter/ignition switch' mystery that I am and have been for some time experiencing so here goes.When I go to start my 73 Stag and turn the key it seems as if it will only start at the end of the turn and just when I am about to turn off and start again.The starter motor was replaced three years ago and the ignition switch a brand new NOS Lucas one a week ago,when having my steering column rebuilt,but lo and behold when starting her again same idiosyncrasy at the end just as I am about to turn the key off.

I had exactly the same symptoms on my Mk1 from the day I bought it & always put it down to a dodgy ignition switch as it would only fire on the return of the key, but would always start.

Once I started using the car on the road I found that once it had warmed up it would start to misfire and then cut-out totally. It then wouldn't restart until it had cooled down sufficiently, which I initially thought was a hot-start issue with the carbs.

I finally identified it had a 12V coil and no ballast resistor, and the white/orange & white/slate wires had been connected on the + and - terminals of the coil! I replaced with a 6v coil & ballast resistor and reconnected across the ballast to the + per the book, and since then it fires up the moment the key is turned, and has never misfired or had trouble hot-starting since.