Originally Posted by Gren_T
It sounds as if the engine earth strap is loose missing or corroded, when you start the vehicle the earth connection is via the handbrake cable.
This is a common issue, I have made jump links for my 90 that link either side of the engine mounts and gearbox mounts I've also upgraded the size of the earth cable & made sure there are a couple of earth connections from the battery.
If you have a woven wire earth strap bin it..
Some of what he said, but I have found that allot of people who remove engines forget where (sometimes) the earth strap was fitted. I have come across earth straps fitted to the bolts where the bulkhead bracket is bolted to the chassis. There is no internal tubes inside of the chassis at this point, so All you are doing is squeezing the chassis together and will never get a proper earth.
The strap should be fitted to the left hand engine mount bracket of the chassis and should be a hole facing aft for it (sometimes)
The welding of the hand brake cable was/is an on going fault to D2's as the strap comes loose.