Morris Minor Owners Club

This is a cheeky question in the hope that there is a fount of all knowledge somewhere!
My Morris is running just fab but I have a 1973 MGB that is not. I have changed the relay but like an idiot did not mark the connection positions. I have an oblong ice cube type with three single tabs and one double but none of them are marked. I have a brown, white/brown, black and red/white and am petrified I will connect up in the wrong order!

_ _
_
_
_
above is how tabs look.
If anyone has a clue I would be over the moon.

What does the relay do ?? Brown is usually LIVE and Black will be Earth. Red/white is usually the feed to the starter solenoid - but I am mystified by the Brown/white....

Hi, It sits on the inner wing next to the fuse box, I assume it handles starter, coil, alternator. As you can tell I am no electrician. Just scared of re-connecting badly and causing damage. The brown and white is a thick wire, same gauge as the solid brown.

I can't find a wiring diagram I can read for the MGB - there are some - but too blurry. Why did you disconnect the relay - it may give a clue to what it does. Does the engine have ballast ignition ? What's not working with the wires off ?? By any chance does it have 'dim dip' headlamps that come on when you are driving ?? Some Minis had that....but I don't know if the MGBs had the system.

Not the relay box for the Lucas 11AC alternator is it?

Maybe, 6RA relay if it is. Is there a 4TR box alongside ??

thank you all for your help. I took the connections off to clean the tabs and then stupidly got distracted! The saga is starter motor was worn so replaced it. At same time replaced points, condenser, rotor arm and coil ( I know it's never the coil and have put old one back just in case) new earthing straps and charged battery whilst it was out, cleaned plugs and checked all leads. Just doing a spring clean and cleaning all the connections. I have checked and double checked they are in place. Came to start car, starter sounds good but it will not fire up. Checked fuel pump and fuel is getting to carbs. Think it must be something really simple and stupid but for the life of me I cannot think what. Sad I know, thinking of pushing it over a cliff. Morris on the other hand is a good as gold and putting up with all the time I have wasted on this MG!

Sorry, no there is no TR box alongside just the fuse box.

Hmmm - you have changed so many things - it could be any of them.. Need to find a readable wiring diagram - do you not have a workshop manual for the B ?

I do have a small manual with a wiring diagram which I have been through. I think that a previous owner did some work on it and I think did not use the correct colour wires. It is one of those where the add said lovingly restored but I have found it would have been better left alone as the more I have got into it the more I have had to re-do and replace. It is a case of heart ruling the head and perhaps should have left well alone but when it goes it is great.

I found a diagram that lists a 'starter relay' - and seems to have the wires you list. The mystery is that your starter is working!!! So - from that diagram - the Brown wire should be on C1, the Brown/white on C2, the Black on W2 and the White/red on W1. The relay should be marked - you may need to look very closely. Clearly the signal from the starter position on the Ign switch is supposed to enter the relay on the normal white/red wire - and the relay sends the signal to the starter on the brown/white wire. Presumably the idea is to protect the Ignition switch....and I assume it is a pre-engaged starter? As your starter works - can only assume the previous owner has wired the starter directly to the Ignition switch...... So it looks like you need to look further for the non-starting problem. As ever - is there power at the coil - and are the points fitted correctly ?
http://www.advanceautowire.com/mgb.pdf Scroll down - it's the 5th diagram.

Thank you so much for the info, it is very much appreciated. Yes it is a pre engaged starter. I will check it all out tomorrow as those indoors are getting restless if you know what I mean! I had re-connected the relay in the right order so will go back to the first thing I did and check how I have connected up the starter. I think all the browns went with the main power supply and the other wire went to a spade on one side.

BMC is correct with the connections and as he says, if the car turned over without the relay connected then it must have been bypassed.
Had a look at my 72 MGB and here is how my starter relay is connected

black _ _ (no wire)

_ brown

_ brown/white

_ white/red

Good morning all and thank you again for your advise. I have put the battery on charge this morning as it has taken a bit of a pounding with my attempts to start the car. Have checked all connections again and cleaned up as many as I can locate. Am going to have the day off and if time will allow re-connect the battery and try again tomorrow. I remember the garage who re-built the carbs a couple of years ago said the distributor was a little worn and had been put back 180deg out. They reset the timing and all up till now has been fine. Have rechecked my new points installation and the gap, firing order 1342. Used thumb over No.1 to check compression with plugs out and TDC. Will let you know if and when it fires up!

180 degrees out matters not a jot - the 'garage' just tells you that to demonstrate how 'clever' they are........

So, forget the relay for a moment, If I understand all of the above, the basic issue is: your engine turns over on the starter, but doesn't fire. So, it's either fuel rleated or spark related. Look at the simple things:

Take the king lead (between coil and distributor) out from the distributor and wedge it close to the block. Turn the engine on the key. Do you see a spark between the king lead and the block? If yes, then move onto the fuel / timing / rotor arm / cap / plug leads / plugs. If no, then use a meter to confirm that you have a 12v supply to the coil and also to the terminal on the side of the distributor (when the points are open). Once that is OK, move on to points / condenser / coil.

For fuel, you say that it is OK, but try pouring a little down the carb. If the engine then fires (when turned on the key!), it's a pump related problem.

It could be any combination of the above, so work through them all methodically and report back.

Well no go! turns over a treat but just will not fire up. checked all leads and connections again. It must be something really stupid that I am missing. Have to work now or else no cash to spend on MG's or Morris and the like.

Thank you for the checking sequence. You are so right there is no spark from the coil, swapped back to old coil with same result. So guess it must be a power feed issue somewhere.

Should be a white wire to the coil (live with Ign on) and then white/black from coil to dizzy.

AHA, I have the white and black x 2 connected to the - on coil and a red one that connects to the coil on +