Which is it?
 

86 560sl just cuts out while driving. Coil? Voltage Regulator? or Fuel pump?

Just plain dies hard, no stumble or warning. Hard to re-start but usually will after a few cranks. Last night I tapped on the coil and around the distrib cap and it fired right up? Coincidence?

Thanks.

JBoggs

Sounds like fuel pump to me.

The coil may be bad as well. Coils generally are hard start culprits...especially in damp weather.

Voltage regulator? Doubt it. It's failure would cause all sorts of irregular electrical issues at once, not just stalling or hard starts.

But a general diagnosis is needed here.

The fuel pump is electric, and it should "hiss" when operating normally. A "buzzing" sound from the pump indicates a problem, or impending doom.

Thank you kindly but..
 

would you be able to listen to th fuel pump under the hood or at the gas tank or ?

Thanks.

JBoggs