MG Car Repair: 77 mgb, vacuum leaks, timing light

Question
QUESTION: When I turn the ignition it starts up no problem. When I let go it dies. Just to see if it would stay running I held it for a few seconds and it will run just fine, will rev up also no problem.

ANSWER: Hi Carl,

Even though it can one of a hundred possible causes to make an engine die at low RPM. Most likely it is either a carburetor problem or an intake air leak. You might also check the air filter as BLM made that car need the air filter to gain enough vacuum to pull fuel out of the jet.

If you don't find any vacuum leaks and the air filter is seated in place, you need to look in the carburetor for a problem. Float level too low, dirt in the jet. diaphragm leaking. etc.

Pull a couple of spark plugs and note the color of the carbon and how much. If it is covered with a fine black powder then you need to check the auto choke too as they are a problem on that car.

Howard

---------- FOLLOW-UP ----------

QUESTION: It idles fine if u hold the ignition on the start position. I don't think it is a Carb problem more of a electrical problem, I think not a 100% sure.

Answer
To separate the starter motor running the engine and the engine doing the running, put a timing light on the coil wire (not a plug wire) and tape the trigger down and watch the flash of the light and use the starter again and release the starter to ignition and see if the flash of the timing light goes out instantly or does it flash all the way down to the crank stopping. This will tell you if it is ignition or not.

Let me know,
Howard