Drove my 85 GSL to work yesterday, everything seemed to be working perfectly. Let it sit in the parking lot for several hours, then went out for my lunch break to discover the car running extremely rough.

Idle was between 400-600 RPM, very erratic, with violent engine shake. If I depressed the throttle, the car would rev, but it sounded almost as if the exhaust was falling off at the engine. (Checked, all connections were tight) Oil pressure was good, level was where it should be.

**What I've checked so far:**
Distributor: Removed cap, replaced rotor, cleaned connections. Checked ignition wires, all have good, clean connections.
Carbureator: Sight bowls indicated fuel level is where it should be. Both throttle butterflies function normally, nothing obstructing the carb.
Exhaust is unobstructed
Tried spraying carb cleaner into the throttle: Ran no more or less erratically afterwards
Checked the fuse panel in the driver's footwell: one blown 15 amp fuse. Replaced.

**What I'm checking in a few minutes**
Replacing all four spark plugs, will try to check the ignition coils.
Will perform a basic compression test to check for lost apex seal. (unlikely, since engine was recently rebuilt)
Replacing two soft rubber oil lines which I've been putting off doing
Will replace fuel filter, check fuel pump.

Any other suggestions on things to check/replace? Am I overlooking anything obvious?

 

if after you try all that and you're still having the same problem, try this:

Remove the plug wires off of the front-most rotor housing and try to start the car. If it starts, put them back on and do the reverse -- remove the wires off the rear rotor housing plugs and try to start the car. It should run with one set plugged in if if that one rotor/housing is fine.

That'll help you determine if the problem cound be a blown seal and/or other things specific to one rotor/housing.

Good luck, and keep us posted.

 

Well, replaced all the spark plugs, wires, the oil metering lines, and some other minor things. Swapped the ignition coils, and... No improvement. Tomorrow, I'll work on the fuel system.

Thanks for the suggestion, I'll definately give that a shot.

 

After running through the entire ignition system and checking all vacuum lines on the carb (one was leaking, replaced), no improvement so I dummy checked myself. Checked the fuse panel once more, and the same fuse was blown. Replaced it, and it blew out almost immediately.

Looking at the fuse diagram, it is labeled "METER BACK" 15 amp fuse.

It had blown once before, and killed the car whilst driving, so I'm off to find out what the fuse runs to. If it's something relatively simple to fix, I'll do it myself. If not, off to an Electrical Systems Specialist she goes.