Intermittent start
 

My 1988 Vanden Plas, about every 20 times, won't crank on first turn of the ignition. It will eventually crank and start the engine, but only after turning the ignition switch on and off several times. I am pretty sure it is due to poor contact from ground to starter solenoid. The problem exists even though I have cleaned both battery terminals and the connection to the firewall. Couldn't I add a ground to the negative battery terminal and connect it somewhere on the engine? Will this work, or does the ground from the firewall have to connect directly to the starter solenoid? Any suggestions?

It sound like you are suspecting the starter. Seems reasonable, so I would reach down (or up whichever is easier) and check the hot cable at the starter. It could be corroded or loose too. Don't forget to unhook the battery though.

I had the same problem and it was the ignition switch. Regards

SOLVED. I changed the starter relay, and installed an additional ground strap. I think that the starter relay was the problem.