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MG MGB Technical - Started, then Died

OK I'm baffled. My '73 BGT has been very reliable and had yet to cause me any problems mechanically. I went to start it after work following my normal starting procedure- I pulled the choke out, turned the key and it immediately fired up. I moved the choke in about halfway and it immediately died. I have not been able to get it to restart. I checked the dizzy and found I have spark at the points. I have fuel going to the carbs. I didnt have any tools to really check further so I had to leave the poor thing on the lot. In thinking back now I dont remember if the ignition light was on or not. We tried a little starting fluid and got absolutely nothing. There doesnt seem to be any spark at the plugs but I couldnt check them to know for certain. All wires appear to be attached as they should. Any ideas? What could I be missing?
william fox

Happened to me once. Turned out to be a bad condensor.
Steve Simmons

William. You need to check for spark at the coil wire. If you have a good spark from the coil to the distributor cap, check at the plug wires. Bad wires will show up more in winter than in summer, as will a bad carbon bush in the dizzy cap and a bad rotor. If you have a good spark at the plugs and fuel, it should start and run. See where the systems are breaking down. Sounds like an ignition problem to me. Les
Les Bengtson

I'm thinking something came loose behind the dash- the tach wire maybe?
william fox

The good news is....you have two months to make the repair before the Missouri Endurance Run for 2005!

bRick
rick ingram

If you *do* have a spark then the tach is OK, but on a 73 the ignition didn't run via the tach anyway as that year changed to voltage operated from the earlier current operated. My first step on a non-starter is *always* to clip a timing light to the coil lead and each plug lead just to see if you get the flashes when cranking, and to check No.1 and 4 are flashing at a few degrees BTDC. If that is the case then you can forget the ignition, with the possible exception of the plugs. But all four failing at once is pretty unlikely, and it will start and run with one failed, sometimes even two. Next up is after cranking a bit take out the plugs and inspect them. Wet is flooded - spin the engine with them out, or if you have a strong smell of fuel when cranking push the choke home and crank with the throttle wide open ... but be prepared to let the throttle go and give it a bit of fast-idle when it catches. A strong smell of fuel on the plugs but not soaked is normal. No fuel smell means no fuel. Firing up for a few seconds, diying, then not retsrating, sounds like fuel pump to me, what is left in the float bowls is usually enough to start and run for a few seconds with the choke out (quite a bit longer if the engine is warm and no choke, incoidentally).
Paul Hunt

thanks Paul. This wasnt a sputter die thing like it ran out of gas. It was a complete shut off like somebody turn a switch off. I was able to pull a plug today and had no spark. I swapped in a spare dizzy and it start just fine. I have it home now. I'm thinking a bad condensor. I'll fit a new one report back tomorrow.

bRick: While this was last year's rally entry we havent picked which car to use yet. I still have my giant killer roadster and Gary has his B that we can fall back on.
william fox

Same thing happen to me it was the fuel pump. I tapped on the pump with a hammer. And tried again herd that wonderful click click click then it fired right up. That was a year ago. I know I am running on barrowed time.

Gerry
Gerry

William - FWIW my fuel pump failure was also like a sudden switch off, not a splutter and die.
Paul Hunt

I have it repaired! I put in a new condensor and nothing happended. I pulled the dizzy again and began to troubleshoot. I found the rotor was STUCK onto the center spindle. I had to break it off to remove it. The end of the spindle was really rusty. I cleaned it off with a wire wheel, installed a new rotor and all is running well now.
william fox

William. If "The end of the spindle was really rusty", you might want to find out if you have any mechanical advance. The "end of the spindle" is really the top of the points cam which attaches to the distributor shaft with a single screw. It also rotates slightly on the distributor shaft, that rotation moving the cam in relation to the points on the base plate--in other words your mechanical advance feature. All of the badly rusted points cams I have examined have been frozen to the distributor shaft and the mechanical advance feature non-working. You may wish to check out yours. Les
Les Bengtson

Thanks for the pointer Les. The rust was just under the rotor itself and not any further down the shaft. The M/A seems to be working fine
william fox

This thread was discussed between 08/01/2005 and 10/01/2005

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