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MG MGB Technical - Engine not cranking

I own a 1972 MGB that has been sitting in my garage for 2 years. I am in the process of trying to get it started. When I turn the ignition key, the starter does not crank the engine, nor does it make a sound. The fuel pump back by the battery is making a clicking sound, and there is a heavy fuel odor. I have checked and I do have power at the starter, and to the ignition. I have power going in to the starter relay on the inner wing, but there is no power coming out. Is there a way to test the relay? Also, I have 4 wires at the wiring harness for the starter, but only 3 connections on the starter solenoid. I've followed the wiring diagram, but I've got one wire left over. Any suggestions that will help me get her started?
Harry

Harry, I can't answer the question about what the 4th wire is for. I have looked in the workshop manual and at the following site too. Both show only 3 connections, all leading to the same point.
http://www.mgbexperience.com/view/?service/wiring-7172.jpg
I may have to stand corrected here, but I think the relay unit is the same as one you can purchase from any motor-spares store. If that is the case purchase one and swap it over to see if the old relay is at fault. I don’t think there are any parts inside any relay which are serviceable.

Finally I would also suggest you have a look at the following site which also gives some further pointers in starting a dormant engine.
http://users.ntsource.com/~barneymg/mgtech/engine/de101b.htm
Cecil Kimber

If you have 12v across the relay winding and you don't have a closed circuit across the relay contacts the relay is bad. But you do need a ground at the relay winding for it to operate. If you have 12v on *both* winding terminals of the relay then the ground is missing. Also the relay will only operate the solenoid if it has 12v on the brown wire on one of the contacts. So the procedure is to check the voltage on all four terminals of the relay.

Also sounds (and smells) like the carb float valves are leaking. After initial rapid pumping, with the engine not running but the ignition on, the pump should not click more than once every 30 secs.

A late 72 (73 model) should have four wires at the solenoid in addition to the main battery cable: a thick brown and a thin brown going to the alternator, a thick brown feeding the remainder of the car electrics, and a white/brown to operate the solenoid (from the relay). The early 72 (72 model) only had one brown (thick) between the solenoid and alternator. In both cases all the browns go to the same solenoid stud as the thick cable from the battery. That should just leave the white/brown which goes on the spade terminal.
Paul Hunt

Many thanks to Cecil and Paul for their feedback.
The 4 wires at the solenoid had no connectors on them so I had to attach my own. I have done this to all of them except one of the thick brown wires. I left this one hanging there not knowing where to attach it.
I will attach to the solenoid stud and test the relay again as you suggested. This should complete the circuit and hopefully get me to the point where the engine cranks. Please check back as I'm sure I'll run into other problems getting her started. -- Harry
Harry

Harry,
Sorry about mis-informing you about the number of wires, I think I had too many Sherries last night and it affected my vision.
Cecil Kimber

Cecil, I guess that's what happens when the Boundary House is turned into a pub. One of your regular haunts, I presume?
John Z

Cecil Kimber doesn't need a pub, he's in the spirit world anyway ...
Paul Hunt

Last night I made sure all 4 wires were attached to the starter solenoid at their proper place. When I tried to crank the engine, the relay now makes a clicking sound. I have 12.55 volts coming from the brown wire into the relay. There is no power coming out of either the white/brown striped and white/red striped wires attached to the relay, nor is there any power coming out of the relay at any other point when I have the brown wire attached and have 12 volts going into the relay. The 4th wire at the relay is the black ground wire. Can I test to make sure the relay is grounded?
The ignition switch has 4 wires attached to it. I have 12.55 volts at the white/green striped wire, and also at the brown wire, but nothing on the other 2.
I should let you know that the dashboard and all gauges have been removed from the car in preperation for new paint. Will this have any affect on cranking the engine?
Best regards,
Harry
Harry

The ignition switch should connect 12v to the white/red wire which is what operates the relay. The relay should connect 12v to the white/brown to operate the solenoid. If there was no voltage on the white/red when the ignition switch is turned to the 'start' position then the switch is bad, but then the relay wouldn't click either.

You need to measure the voltage on all four terminals of the relay with the ignition switch in the 'start' position. You should have 12v on the white/red, brown and white/brown wires and 0v on the black. If you have 12v on the black the ground is bad. If you have 12v on the white/red and brown but not the white/brown the relay is bad. If you don't have 12v on the brown there is a bad connection or open-circuit in the brown. If you don't have 12v on the white/red the ignition switch is bad or the white/red is open circuit or has a bad connection.

Lack of gauges won't have any affect on cranking - assuming you don't have the capiliary gauges.
Paul Hunt

This thread was discussed between 28/05/2002 and 31/05/2002

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