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Curtis, Australia Car Mechanic
Category: Australia Car
Satisfied Customers: 1609
Experience:  Qualified Automotive Mechanic, LPG & Airconditioning Diagnostic Technician.
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MG series: , my 1970 MGB with twin SUs (just overhauled)

Customer Question

Hi, my 1970 MGB with twin SUs (just overhauled) and new spark plugs is hard to start when cold but once started (after 15 mins) it goes well.
Once on the open road and it's warmed up it decides to die to a total stop (3 times on a 1 hr trip). It will eventually start again and run perfect until it decides to die again. I don't think it's fuel as it doesn't run rich or smell of fuel. Could it need a new coil as I'm totally lost for ideas. Regards Dave
Submitted: 2 years ago.
Category: Australia Car
Expert:  K. Wiggins replied 2 years ago.
Hi Dave, do you have a multimeter handy so we could check the coil?
Customer: replied 2 years ago.
Hi there,
I've just replaced the coil with a brand new item. No change, I wasn't able to start the MGB today but it did fire and run for a very short time. Regards Dave (TALES)
Expert:  Gary replied 2 years ago.
Hi Dave,I've had many experiences with twin and triple SUs.I'll assume the carbs being overhauled means all new replacement parts.So now, have the carbs been balanced and mixture strength set correctly?Do you use the choke for cold starts?Do you know the age of points, condensor, cap and leads?Gary
Customer: replied 2 years ago.
Hi Gary,
Carbs are totally overhauled, balanced & mixtures set. I use the choke on cold starts. The points, Condenser, cap & leads are all new. I have just noticed I have power in & out of the new coil but no spark in distributor (points) Now the motor winds over but won't fire.
Cheers Dave
Expert:  Gary replied 2 years ago.
Hi Dave,If you set the engine up with the points closed, ignition key on and open the points with an insulated tool, there is not a tiny spark across the points?Can you connect your test lamp (not LED) to the negative of the coil and ground, ignition on, turn the engine by hand, the lamp should go on and off as the points open and close. If the lamp stays lit permanently you have an open between the coil negative and the points ground plate. If the lamp is not lit at all you have a shorted points circuit.Hope this helps.Gary
Customer: replied 2 years ago.
Thanks for that, I'll give it a try.
Expert:  Gary replied 2 years ago.
Hi Dave,Let me know how you go, and if you need any more help, just ask.Regards.Gary