Friends,

I am still troubleshooting my 1991 420SEL.  My brother is helping me as I am
not mechanically inclined, so please forgive me if I misstate anything.

Here is the list of things I have done so far.

1. Replaced fuel pump relay, overload relay
2. Replaced distributor cap/rotor
3. Replaced fuel/air filters
4. Temporarily replaced fuel distributor
5. Replaced battery
6. Checked fuses in the engine compartment
7. Temporarily replaced ignition box near driver side wheel

It seems to get fuel through the fuel distributor.
The fuel pump sounds like it's working when I turn the key.
No leaks, no smoke.
We get spark at the cylinder.
Timing seems to be in synch.
Gas tank is 3/8 full.
Never any backfiring or hesitation in the past.
Starter seems to be working fine; engine tries to turn.
*Sometimes was hard to start (before new battery).
*Cruise control never worked for me.
*When we try to start it, sometimes it makes loud knocking but doesn't
start.
*Initially stopped on the road after I floored it at 15 or 20 miles an hour
to enter a residential street, no hot-rodding.
Has sat in my driveway for one year, unable to start.

Thanks,
Ron in Salem OR