Viva GT Intermittent starter failure (now sorted!)

[Colin]

I have an electrical problem with my 68 Viva GT. It's in standard trim - 1975cc OHC engine with twin Strombies etc.

Nineteen times out of twenty, turning the ignition key results in a 'click' from the starter solenoid as it tries to engage, accompanied by a big voltage drop showing on the ammeter. On the twentieth try the engine turns over OK and coughs into life, but runs very roughly, sometimes only firing on two or three cylinders and then dying under any sort of load when firing on all four.

I have found the starter 'fault' can be lessened by jump starting from another vehicle - ie more likely to get it to turnover - but not always.

So far I have eliminated -

1) Battery - replaced with new 55 Amp / hour unit

2) Starter & solenoid - checked and changed with a known good one from my other GT - symptoms exactly the same

3) Earths - I have checked and cleaned all battery / starter / solenoid / alternator / coil connections and earths

4) Charging - the alternator seems to be charging. Again all connections checked / cleaned and secured

5) Coil - believing the rough running and apparent starter solenoid failure to be two different issues, I changed the coil for new Lucas non-ballasted 'sports' coil. The car had been fitted with a 'cold start' coil but apparently without a ballast resistor (I don't think it would have had a ballast wire in the loom in 68) -again no difference to rough running symptoms. Points gap checked and ignition timing checked OK

I'm scratching my head now and wondering whether I might have a short somewhere between starter, ignition switch and coil.

I'm mightily fed up about this because it means I'm not now going to able to drive my Viva GT to Billing

Any help anyone can offer would be greatly appreciated!

Thanks

[AccieMad]

Blind guess. Have you tried by-passing the ignition switch and firing the solenoid manually or from the battery with leads and see if it spins straight up.

If the switch is poor then maybe the voltage to the solenoid is low and you are not getting a proper connection.

Just a thought. No expert.

[Colin]

You mean hot wiring it? Bypassing the ignition switch - I will try that first thing tomorrow.

If it is the ignition switch causing a voltage drop then perhaps bypassing it may allow the correct voltage to reach the coil and have an effect on the rough running? The symptoms of which do present like very weak high tension.

The ignition switch itself does seem to be working - in so far as some power is clearly getting through to the solenoid to make it go 'click' - but apparently not enough to throw the big starter switch!

I did try the live battery lead direct to starter and that spins it over straight away, but I had already established the starter and solenoid are OK by swapping them with my other car.

Thanks very much for the helpful suggestion.

[1972nail]

Take the plugs out and see if it turns over OK. Without compression it should spin away quite happily if the starter and battery are both good. If not, then suspect something electrical, wiring, switch, solenoid, starter.

Will the starter work OK in the other Viva?

[chrismc]

I know you have checked the wiring but could it be the main engine earth strap? Easily checked by connecting the engine block to a good earth point ( bumper?) with a jump lead.

[Colin]

Thanks again for the above suggestions - both already tried.

I'm now thinking around a possibly faulty ignition switch - so will try to source a replacement HB Viva switch (I think the MK I GT ignition switch is common to other HB Vivas).

I remember prior to this problem the ammeter was getting quite hot. That is obviously on the same ignition circuit -so could be a clue!

Thanks again,

[Colin]

I've now finally resolved this problem (!)

It was a short in the ammeter - which of course only manifested itself with the ignition switched on!

I've bypassed the ammeter and the car now turns over and fires immediately every time. It's now running as sweet as a nut - (which it should having had a new battery, coil, plugs, points, and a thorough ignition tune).

The fact is that the ammeter sits in the ignition circuit between battery, starter and ignition switch and if it begins to short internally for any reason the whole ignition system will lose power - which explains the lack of starter solenoid power, very weak ignition high tension and even the very slow indicators!

Took the car for a spin around the hills today, running great. Shame I couldn't have managed this before Billing though...

[1972nail]

The same problem happens with the early 'Ammeter' 7 dial dash for the HC. It was later swapped for a more reliable 'Battery Condition' meter which measures charging voltage instead of current. Most 'experts' would say that the ammeter is a better indicator of charging circuit and equipment condition than the battery meter but for most people the battery condition meter is just fine.