1990 740 turbo stalls

1966novacoupe · Post by **1966novacoupe** » 22 May 2016, 20:14

recently my 1990 740 turbo started stalling randomly. now its every 10 or 15 minutes. fuel pressure stays at 43 psi constant. fuel pump never shuts off until after the engine stops. when the engine stalls, First the tach instantly drops to zero, then engine stops at the same time. i have to turn the key all the way off first ,then it will usually restart as normal but stalls 10 minutes later. doesnt matter driving or idling. going fast or slow. when it stalls the tach hits zero and the engine stops at the same time. no sputtering or gradual slow down. i tested the coil and found battery voltage going in [13.1] and about 12.86 coming out. also hooked my timing light up to the coil wire and watched. as soon as the tach dropped, the spark stopped at the same time. replaced the rpm sensor. no hall effect in the distributor in this one. im stumped. any help or ideas is appreciated. no other issues with the car. thanks

lummert · Post by **lummert** » 22 May 2016, 23:09

Sounds like an ignition system problem. Ignition power stage or crank position sensor.

1966novacoupe · Post by **1966novacoupe** » 23 May 2016, 04:03

thanks for the response. ive already replaced the crank posistion sensor [ rpm sensor ] so im going to try the ignition power stage amplifier. thanks.

lummert · Post by **lummert** » 23 May 2016, 08:33

You may want to try to find a used power stage to test the theory before spending $80+ for a new one. Also, if you end up buying a new power stage save your self some grief later on by buying a Bosch part.

1966novacoupe · Post by **1966novacoupe** » 23 May 2016, 19:43

thanks lummert, put a new bosch ignition amplifier in tonight after work. car has already run 1.30 hours. hasnt skipped a beat yet. i think we nailed it. thanks for the help. steve

lummert · Post by **lummert** » 23 May 2016, 21:42

You're welcome. Funny my name is Steve.

1966novacoupe · Post by **1966novacoupe** » 24 May 2016, 13:16

kool, people sometimes get me mixed up with steve,s nova site because i have a 66 nova ss coupe..

1966novacoupe · Post by **1966novacoupe** » 26 May 2016, 10:35

follow up, three days, lots of miles and the car still hasn't skipped a beat. thanks again for the support and suggestions steve. steve