I have a 2001 ram 3500 cummins that at times will crank over fast but wont start. I have a rapter aftermarket fuel pump. I had codes pulled the other week but cant find print out but I think it had a crank sensor code. I have noticed that at times the tich quits working & tonight while trying to find loose or bad connection I turned off ignition & it would not start. after about 30 to 40 mins it started & tach was then working. I've been told could be dealing with a computer problem.