MG Car Repair: Ignition Problem, fuel pressure gauge, electronic fuel pump


Question
My 1979 Midget periodically stops running.  It normally happens as I am slowing down.  The starter cranks just fine but the engine will not start.  When I turn the ignition off for three or four minutes it will generally restart.  I have an electronic fuel pump which seems to be pushing gas and have replaced the distributor and rotor.  Could this be an electronic ignition issue.  Your advise is appreciated.

Answer
Hi Barry,
It is no use throwing money at the problem until you know what is wrong.
All testing must be done in the failed mode. It is no use testing when it runs good. This means you must be able to see what is missing at the time it fails. (when you are slowing down)
All engines only require three items to run, compression, fire and fuel. It is unlikely that it is compression as compression does not go away and then return later. So that leaves fire and fuel.
How to watch fire and fuel while you are driving is not as hard as you might think. All you need is a timing light and a fuel pressure gauge and a little extra hose.

First connect the timing light up and clip the pick-up on the coil wire not a plug wire. Run the wires out from under the hood and tape the trigger down and place the timing light under a wiper arm and if the sun is bright, tape a piece of cardboard over the end of the light onto the windshield so you can see the flash of the light from the cockpit.

To test fuel supply, put a "T" in the fuel line at the carburetor and run a long hose out from under the hood and place the gauge under a wiper arm so you can watch it too.

Then drive the car and watch to see which is lost when you slow down.
One or both have to be lost for the engine to die and not start right back up. The only other thing you might want to do for testing is to remove the vent hose off of the carburetor as a third test.
Let me know,
Howard