My 1982 Volvo w/ mechanical fuel injection (K-jet) has a "bucking" issues. When driving down the road the engine will temporarily cut-out for a second or two. The odd part about this is that the tach will not go to zero when this happens. Instead, if I am running the motor at say 2500 rpm, the tach will jump to 3000 and then down to 2000 and then back to the correct rpm when the motor comes back. It hasn't stalled on me while driving at speed (knock on wood). It started doing this after I had my car worked on by a "Volvo specialty" shop. Prior to taking it to them I did a complete tune up but could not get the distributor cap off. I took it to them for this and a timing belt.
They ended up breaking the original distributor (originally the white chrysler unit) and replaced it with what they said was an upgraded Bosch unit. Ever since I got it back, the car hasn't run right. For the past 5 months they have put in different distributors (none new), swapped engine control modules, and redone the distributor wiring harness.
I got frustrated so I ended up replacing the following parts after the problem occurred which did not help either:
Main fuel pump
In tank pre-pump
Coil
The following was replaced with new parts prior to the problem occuring:
Spark plugs
Wires
Flame trap
Fuel filter
The following parts were replaced and then I started having a problem:
Distributor (used bosch model - done it with two other bosch models also)
Pick-up coil
Cap
Rotor
Timing belt
Any suggestions? I am about ready to buy a new distributor for $200. I have read that the wiring harness going to the coil has been known to rot away after time. Also, any ideas on how to diagnosis this problem? I have spent many hours and a lot of $$ in paying people to diagnosis a problem that still hasn't been found. Thanks in advance
