MGB 77 dies in motion

I’ve been with the same mechanic for several years and believe he knows what he’s doing. But, now he’s stumped.

1) Thursday while driving 35 – 40 mph the car died, as if I had run out of gas – popping the clutch as it cruised at diminishing (but adequate) speed did not bring it to life. Once stationery, car would not start. 2 hrs later towed to mechanic – Monday morning mechanic found the fuel pump pumping, all else fine except the points were too closed so he opened them. Paid $80 bill and I drove it home 15 miles, plus another 2 miles in the next week.

2) Monday morning, after 2 miles, car died while idling at stop light, as if I had run out of gas. Car not start. Pushed off road onto side road, found phone, called tow truck, work, mechanic. Car not start. Knocked on fuel pump casing in trunk. Car not start. Car still stationery. 20 minutes later car started. Drove 5 more miles to work, then 10 miles to mechanic after work at 5pm.

3) Tuesday afternoon (today) paid $194.75 ($104.75 pump + $30 overnight shipping + $60 for 1½hr labor) and picked up car. Drove ½ block and car died – as if I had run out of gas. Car not start. Fuel pump pumping, juice was there to spark plugs, tightened condenser. Car started about 20 minutes later.

4) I'm living on borrowed time – mechanic doesn’t know if it will die again nor do I.

Can anyone help?

Though this might not be the problem, the same thing happened to me. The car would die on me unexpectedly, sometimes on the highway or just wouldn't start after parking it. Other times it started fine. After a few days, I found my problem. Loose, corroded connection on low-voltage side of coil. Even though things might look like they're working, you're problem is intermittent and so you're cause must also be intermittent. I'd jiggle and clean any dirty connections. I think there is a fuel cutoff switch in case of a collision on late B's, maybe check the connections to this item. I'm sure someone will have some common problem areas to check. Too bad about the pump...
Good luck.

I have had similar problems. Each time that it happened to me, I noticed a lack of fuel in the fuel line filter under the hood. The fuel pump is fairly new so I eliminated it as the problem. I have traced it to a lack of fuel caused by the "interia" switch tripping.

This is a switch, cylinder shaped, located under the dashboard near the steering column. It is designed to prevent fuel coming to the engine if the car rolls over, or is in a crash. It has a knob that sticks out from the bottom. If it is tripped (caused by a bump or going down a sharp incline), the knob needs to be pushed back into the cylinder. It may be faulty and needs replacing.

Best of luck.

Jackie, Ameer and Graeme both have good suggestions, but one thing that is often overlooked that can cause fuel starvation is a clogged vent line. If the car quits on you again, get out and remove the gas cap. If there is a sucking sound like a an air leak, it's because the gas tank has vacuum in it caused by a clogged vent line. No sound, no problem with the vent.

It might not be fuel. I had the same problem in 2 cars where the cars would die in motion and restart after sitting for 20 minutes. the problem turned out to be ignition module. when the module got hot a short would open and the car dies. after sitting and the module cooled the car would restart. I have driven both cars for several years with no problems after replacing the module with a Crane after market replacement unit.

I had a similar situation on my '79 B. It was the center ignition wire that did not fit right on top of the Mallory distributor cap. It was slowly pulling out when the engine was hot and the car would die anytime. The rubber 'cup' was too tight at the end of the wire and it was impossible to see anything wrong... I just glued it on with orange silicone sealant and it stopped to problem. Next time I change the wires I will check that they fit properly.