E350 Starter issues
 

I have an 1995 E350 chassis in a Class C RV. I have had some intermittent starting issues. 1 out of 10 times, when I turn the key, nothing happens for 2 seconds and then it starts cranking. I have replaced the ignition switch on the column and the solenoid on the firewall.

The RV only has 60,000 miles and the starter looks real clean. The heavy gauge wire from the starter to the Solenoid on the starter is clean.

I am thinking it could be the key tumbler.

What else could it be? As it is intermittent, I am not sure how to test it out.

Any thoughts?