engine won't start 1990 740 4 door sedan
 

I turn the key engine turns about 4 turns and stops, I do this 7 or 8 times engine won't start a friend gives me a jump thinking maybe low battery. In meantime, I have kept the throttle wide open now go back to 3 or 4 turns and stops. After 5 to 6 times, 1cylinder pops ahhh lt lives. I keep cranking it till it clears its throat and starts. I suspect it is in the key switch so I am going to run a jumper to the solenoid to a push button switch, to the positive and if it keeps cranking I will no it is the key switch THANKS but I think I solved the problem what do you guys think ???

did you look at wiring diagrams to see if there's a relay in the path from the key to the starter? I doubt if Volvo would design the key switch to manage a lot of current - just the voltage to drive a relay. That's where I'd be looking.

Volvotips.com is a good site for an online repair manual and should have a wiring diagram.

I ran a wire from the starter solenoid to a momentary on button, then to a positive wire I turned on the ignition hit the button and the engine starts so I believe the cranking problem is in the key switch cause the engine will keep cranking as long as I press the button with the ignition turned off Is there a mechanical choke or is it done through the computer and the injectors? I do believe the engine floods itself when it turns over 3 or 4 and quits through the ignition switch