QuestionQUESTION: Hi, I have a 77 MGB over a year now and am a first time owner and am quite a newbie. I have a dilemma however. My ignition switch failed. The spring-back part of the switch no longer worked. It would not turn the starter over whatsoever as the switch failed. I found on a website how to start the MG "under the bonnet" without the key. I thought I'd try that - in essence hot wiring my own car so I could get it home and do the work there. By jumping the live brown wire from the starter relay to the bottom fuse, at the same time as connecting the coil spade to the same bottom fuse, the starter would engage but the engine would not start, it would only turn over. Could I have I screwed something up-maybe blew some sort of starter solenoid as all it does is turnover but won't fire. I changed the plugs just to be sure. The real strange thing is the car always started easily. Only when the ignition switch died and I tried to "fix it" will it no longer ignite?
I found a replacement ignition switch and installed it. It seems to be illuminating the correct lights on the dash as well as "spring back" when you turn the key. But the lack of firing still exists. I have power at the fuel pump, as well as the pump will fill fill a jar relatively quickly if I unhook it from the carb. I think the pump is ok. I guess that leaves the ignition or the fire part of the equation. (I'm quite confident compression is not the issue as it has always started easily and wouldn't not arbitrarily lose compression because of a faulty switch).
So as I wrote earlier I'm quite a newbie but don't know where to turn now. PS The inertia switch does not appear to have been affected. However I do not know how to test that. Any help would be appreciated.
Regards,
Kevin Muldoon,
Kemptville Ontario Canada
ANSWER: Hi Kevin,
First what kind of ignition system is on the car? The original system is not usually still working as they had a high failure rate.
Howard
---------- FOLLOW-UP ----------
77 mgb
QUESTION: Hello Howard,
It appears to be an aftermarket electronic ignition system from Lumenition.
Also I just confirmed that there is no power at the coil. Tested with a 12v tester.
Again, thanks in advance.
Cheers
AnswerIf you have no power at the coil with the key on, that has nothing to do with the ignition system as the power should get to the coil before the ignition system. All ignition systems ground the coil to make it load then they break that ground which makes the coil magnetic field transfer to the secondary (coil wire to the cap). So you have a wiring or ignition switch problem. Take your wiring diagram and follow the color coded wire from the coil back to the switch and test with a test light as you go. If you don't have a diagram, let me know and I will put one on my web site for you to copy.
Howard
