I replaced the master cylinder on my 98 Dodge Ram 1500. I bled it and all the wheels. It didn't solve the problem. Ive read and been told by mechanics that the master cylinder was the problem. I must have done something wrong. I bled it again. Still didn't work right. It occurred to me that maybe I should be bleeding the system with the engine off. So today I tryed to bleed the master cylinder with the engine off. I loosened the brake line pushed the pedal down all the way, held it there, and tightened the brake line. I did this 3 or 4 times for each line. Now it won't start! I can't imagine how the two can be connected. Any ideas?

 

Sounds like you disturbed a connections somewhere. Is this a 5 spd by-chance? Maybe you knocked the clutch pedal switch connector off.

 

I'm not sure about it not starting, but when bleeding you should not push the pedal all the way down. Have someone in the truck pump the pedal a few times and then hold pressure. With pressure on the pedal, loosen the bleeder nipple (not the line) and let out a little fluid at a time until the air bubbles stop.
Close the bleeder before the pedal is released, otherwise you are sucking air in to the system. Also, pushing the pedal all the way down can damage the master cylinder because you are over extending it... making it go beyond it's normal range of operation.
Also, bleed the brake farthest from the master cylinder first, then make your way around the truck till you end at the brake closest toe the master cylinder.
Engine off.

 

Does the motor crank & not start or will it not even crank? If it cranks, check for spark & fuel pressure. You can hear the fuel pump turn on when the key is 1st turned on (about 2 seconds) then check for pressure by opening the needle valve on the Schrader?? valve that is on the fuel rail to see if fuel squirts out (be careful with this, have a rag handy). If no spark, then it's possible that either the CPS (crank sensor) or cam sensor has gone bad... if the ECU doesn't know what position the motor & cam are in then it won't provide the signal to the coil for spark...