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MG MGB Technical - Help. Fuel or Electrical?

I have a 78 MGB that I have replaced the fuel pump with the newer pointless pump and installed a Weber DVG carb. Also have a new coil and fuse box. Problem that existed prior to all the new additions is that the car will run (although rough) for about 1 to 2 min and then stops. It will start up agin and run for about the same time again before quiting. The tach slowly decays to zero. I have removed the fuel line and ran the pump into a can and the flow seems adequate to a novice like myself. Also I have replaced the charcoal cannisters with new ones. Could any of you kind souls tell me where to look next? I am about at my wits end. Thanks in advance. Ed Johnson
edward johnson

Sounds like you electronic ignition is taking a crap The decaying tach is a big clue. There are several good alternatives as the stock one is no longer available. I am, of course, assuming you have the stock ignition. Chuck
Charles O'Brien

Ed. Most of the original Opus systems have been replaced years ago. The one on my 79 failed at three months from new and was replaced by the dealer under warranty. The sign of a low tension problem is not a decay or slow dropping of the tach, but a sudden drop to zero. Get a vacuum/fuel pressure gauge (they cost about $20) and measure the pressure of your fuel pump. It should be at least 1.75 psi for a new pump. The flow rate should be about a quart a minute. Check the float level on the Weber. I have seen them set too low. As Ed notes, knowing what form of distributor you are using would be a good idea. Les
Les Bengtson

Clip on a timing light and look at it. If it still flashes when the engine won't run it isn't ignition.
Paul Hunt

This thread was discussed on 12/09/2002

MG MGB Technical index

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