Ignition light flashing in unison with fuel pump

[millmoo]

A relative novice asks:
The problems began with the ignition light coming on 2 weeks ago on by 1970 2 door. Fitted a new dynamo and all seemed ok, then starting problems occurred. Engine turned over but wouldn't start. Found fuel pump wasn't clicking so my son replaced that. He was driving yesterday when the engine cut out at low revs. Wouldn't start again-no fuel pump clicks, even starter button in engine bay won't turn fan more than a 1/4 turn. Engine started fine after bump start. Same thing happened to me today. I checked the engine bay to find he'd put the battery back in the wrong way around. Changed it around, and the engine started, but the ignition light came on, and flickered in unison with the fuel pump action. Stopped engine, tried starting again, but again nothing happened, no fuel pump , no starter sound. Has the polarity on the fuel pump been reversed? Is there another issue here? Also, how would a voltage regulator problem appear? I plan to get a voltmeter tomorrow to check.
Will recheck battery terminal connections too.
Thanks, Jeremy

[PSL184]

Switching the battery polarity on a dynamo car shouldn't make any difference. The action of running the engine the first time usually re energises the dynamo to run in the right (electrical) direction. However, the fuel pump points and the distributer points may object to the change in polarity and should ideally be replaced with new or at least cleaned with emery and reset.Without a voltmeter you can't go any further with your diagnostics - You need to know if the battery is getting a charge and if it is holding a charge also. Check all connections are clean and secure and get a meter to take some readings... report back and we'll advise accordingly....

[aupickup]

if the battery has been turned round poss to neg earth, then the contacts on the coil should be turned round and the dynamo flashed, but still should start

[bmcecosse]

Sounds like the battery is completely flat - charge it up before spending any more money! If the dynamo doesn't self-polarise you will have to encourage it by taking a wire from the non-earth termianl of the battery - and 'flashing' it against the smaller of the two terminals on the dynamo. Probably the regulator is ok. Also check the fan belt is tight enough!

[millmoo]

Hi Guys, thanks for the quick replies.
Concerning the fan belt, how tight should it be? I can barely turn the fan/dynamo as it is.

[PSL184]

you should be able to turn the fan by hand which should, in turn, turn the dynamo - Sounds like yours is OK.

[millmoo]

when I turn the fan, the belt doesn't move, the fan slips underneath. Perhaps too tight? But back to the ignition light, the battery was definitely part of the problem, as it started straight off from the jumper leads, but the red light is still on and pulsated in unison with each clip from the fuel pump. Any more ideas?

[millmoo]

sorry that should read "with each click.."

[bmcecosse]

As above - you now need to polarise the dynamo using a length of wire.
And sounds like your belt is too SLACK. When you turn the fan by hand - the belt should move with it - and indeed turn the engine if you have the strength.

[millmoo]

reversed leads on fuel pump and reversed polarity on dynamo and all seems fine now. No more flashing!

[bmcecosse]

Don't know how you could 'reverse leads on fuel pump" ! It only has one lead - and an earth wire. I assume you re-polarised the dynamo ?

[alanworland]

How can you fit the leads 'the wrong way round' on the battery? The +ve and -ve terminals are different sizes?

[bmcecosse]

Only slightly - and if you 'want' them to go on - they will! Especially if they are the clamp type.