I had an ignition problem (91 740, Non turbo)and eventually (with the help of this forum and others) found out it was a bad coil. Expensive to replace ($165) but I also found that the test someone had posted for checking a bad coil was not accurate for a Bendix-Regina coil on 91 740s!

Good Coil Test:

I tested the primary resistance (between the positive and negative posts) and on my good coil it read .001 ohms, essentially nothing.

I tested the secondary resistance between any of the positive or negative posts and the lead to the distributor cap wire and it did not register at all, no electrical connectivity at all, no reading on the digital multimeter

Bad Coil Test:

Primary resistance was still .001 but the secondary resistance was 1.6 ohms when it should have not registered anything at all.

The kicker was that the bad coil was still pushing juice, just not enough to jump the gaps on the cap.

I think what stressed my coil and caused it to fail was the plugs were gapped at .035 instead of .028, the wires had twice the resistance of a new set I put on there, the rotor had a small crack in it, and cap pick ups were worn.

Hope this helps someone else out there.

Cheers
Chad

 

This was helpful, I'm battling with a hot stall on a Regina 740 right now and testing the coil in this way shows that its bad. It also *looks* bad, the core is all rusted.