I have just finished installing a TBI fuel injection on the 250ci inline6 in my '57 Chevy Suburban (I have also swapped the TH350 trans for TH700R4, but I do not think this has anything to do with this issue).
I did try to start the Suburban a few times in the last week, with no luck: my install needed some trouble-shooting! As a result, the battery of the Suburban (which up until a month ago was in a daily driver and very strong) is now dead, totally dead, like in no radio, no click from the solenoid, no headlights, really dead!
So I want to jump-start it with my '93 Buick Roadmaster, easy...
Well, no!
When the 2 cars are connected, the Suburban starter motor still barely spins and then nothing, again... like it is not "receiving" the electricity from the Buick;
Then, after a few minutes (less than 10), the handles on the jumper cables get hot, very hot, so hot that the plastic handles on the clamps start to melt...
And then, the Buick dies, dead battery!!!
The jumper cables are good quality, heavy enough, I have used those for many years; the connectors on the Suburban are very clean, both on battery and starter motor; the Buick is very clean overall.
What is happening?
And how do I fix it?


'57 Chevy Suburban; '70 Chevy Impala.