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78 b wont start

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78 b wont start #1
trialsrider Richard Bussler South Williamsport, PA, USA Sign in to contact 1959 MG MGA 1600 "Flipper" 1998 Triumph MC Adventurer	Topic Creator (OP) Oct 25, 2014 09:35 AM Joined 10 years ago 972 Posts

78 mgb will only run if the starter is engaged what gives

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Re: 78 b wont start #2
SchrumMG Caleb Schrum Lincolnton, NC, USA Sign in to contact 1978 MG MGB	Oct 25, 2014 09:49 AM Joined 10 years ago 81 Posts

Check the points, gas tank, coil and plug wires

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Re: 78 b wont start #3
ErnieY Ernie Y Albatera, Alicante, Spain Sign in to contact 1976 MG MGB GT	Oct 25, 2014 09:56 AM Top Contributor Joined 12 years ago 19,528 Posts

Check the ignition switch or the coil ballast wire.

When cranking the ballast wire is bypassed by an auxiliary contact on the solenoid which provides what is in fact a 6v coil with 12v to aid starting.

When you release the starter the contact opens and places the ballast wire in circuit to supply the coil with the lower voltage.

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Re: 78 b wont start #4
trialsrider Richard Bussler South Williamsport, PA, USA Sign in to contact 1959 MG MGA 1600 "Flipper" 1998 Triumph MC Adventurer	Topic Creator (OP) Oct 25, 2014 12:33 PM Joined 10 years ago 972 Posts

Problem solved for now corroded terminals on starter relay

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Re: 78 b wont start #5
ErnieY Ernie Y Albatera, Alicante, Spain Sign in to contact 1976 MG MGB GT	Oct 25, 2014 12:54 PM Top Contributor Joined 12 years ago 19,528 Posts

That doesn't actually make sense because all that does is drive the starter solenoid and if there was anything wrong with it the engine wouldn't crank, it's nothing to do with the ignition.

I wonder if you disturbed the end of the ballast wire which is in the same general area.

It looks to be encapsulated but corrosion can get in there making it intermittent - ask me how I know - it took me a couple of weeks to track down why my engine would suddenly stop but only once or twice over several days but always start up again immediately and that was the cause.

IMG_3075.JPG 35.3 KB

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Re: 78 b wont start #6
trialsrider Richard Bussler South Williamsport, PA, USA Sign in to contact 1959 MG MGA 1600 "Flipper" 1998 Triumph MC Adventurer	Topic Creator (OP) Oct 25, 2014 12:59 PM Joined 10 years ago 972 Posts

Well after cleaning those contacts it got power to coil and fired right up by the way it has a mallory duel point and sport coil

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Re: 78 b wont start #7
balist steve bali Vernon, BC, Canada Sign in to contact 1962 MG MGB	Oct 25, 2014 01:00 PM Top Contributor Joined 13 years ago 645 Posts

Dear Richard,
Ernie is correct, a faulty ballast resistor will give you the condition you described. Corroded terminals would not allow the starter to run

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