Car started fine cold. Idled for about 10minutes without issues. Checked out the fused relay behind the battery no issues there.
Turned car off, washed it and now it will not start. Never a dull moment...

Based on your short description, is it safe to assume that you have done just a basic level of maintenance (fix when broken)? Some 1989 cars already have the OBD I system (Diagnostic Trouble Code), refer to what the codes are telling you to address.


Here's my very basic (not a comprehensive list), relatively cheap parts and DIY fix check list I refer to whenever I pick another MBZ (9- W124's, 14 times overall since 1990). If I'm not absolutely sure that the part isn't 100%, then I replace it (but I keep the old part as an emergency spare).


I would think that your trouble lies within the first 5.


1. Voltage regulator: $15, replace it just because. (Is the ABS light also intermittent?)
2. OVP: $15, same as above
3. EHA: $100 for good, tested, used one with a decent warranty, if it's leaking from one of the weep holes, replace it
4. Fuel Pump relay: $25, replace
5. Dist Cap, Rotor, plugs, wires: $100 total, replace
6. Fuel filter: $20, replace unless you know for sure it's less than 2 years old.
7. Air cleaner: vacuum it, make sure you can see light through it
8. Oil and filter change: $30, you want to see what comes out when you drain it
9. Transmission oil and filter change: $40, same as above
10. Radiator Flush, Fill + Thermostat: $50, same as above

__________________
03 CLK430 Cabrio 211K Pweter Silver/ Oyster Leather
90 300SEL 214k Pearl Black/ Alto Grey/Black Leather

Prior: 85 190E, 88 300TE, 89 300TE, 90 300E 2.6, 90 300TE, 92 300E 2.6, 91 and 93 300SL, 87 Ferrari Mondial Cabrio