I have a '97 Dodge truck with a 5.9 Cummins diesel. It doesn't start like it should because the fuel shutoff solenoid doesn't always open the fuel shutoff valve to the fuel pump when the key is turned to start. If I "jump" the contacts on the shutoff solenoid directly from the battery, it works fine. I am not sure what else to check. Could this be the result of a bad ignition switch not letting full power go to the shutoff solenoid while cranking the engine?

Or, the book says there is a "fuel shutoff solenoid relay" somewhere in the circuit, which could be a problem. Does anyone know where this relay is located?

With the key turned "on", I can manually move the shutoff solenoid, then crank the engine and it will start.

Anyone got any ideas of what I can try next?

Is the solenoid getting 12 volts with the keyswitch on? I stick a small needle or safety pin through the wire insulation then connect a voltmeter or DVOM to check for voltage on my stuff.

This is a notorous problem. Replce the solenoid. Its weak.

Before you replace the unit to the tune of $150.00 or so, take it out [ very easy, two bolts and a pin below] and clean it and check the rubber boot around the shaft. The rubber gets torn sometimes and lets dirt and crud in . Oh yes , unhook the wires when removing it. Easy job and could save you a bit of money. The selonoid that controls it is on the firewall. When the ignition switch is turned to start there is 12v to the seloniod and when it is on run it is cut back to 8v or so...............