[michel.s]

Sudden e fine dying is probably an electrical problem since the car runs well after it atarts:

1- Crankshaft position sensor. A bad one will kill the engine when it warms up. You can check its resistance immediately after engine dies and if you got a bad value than this is your problem. You can search this forum for resistance values and testing procedure.

2- Fuel pump relay and not OVP relay. The OVP never cause a sudden engine dying. A bad fuel pump relay will break contact when it gets hot due to cracked solder joint and it will shut off thd fuel pump and so the engine.

3- Distributor cap and rotor. It will be a good idea to check all the ignition system from coil to spark plugs wires. ( Whn you washed the car there was humidity, a little problem with the ignition system will cause a non start and engine dying in humidity but it wont run very good as well as there s humidity still in. Thats Why i ruled out this scenario.

 

[michel.s]

I think the first thing I am going to do is try to run the car with the OVP relay out as I already have it out from testing it. I am hoping the engine will shut off, meaning its a fuel issue. From there I will pull the fuel pump relay and see if I can fix the solder joints. And again check from there.

OVP or No OVP your engine have mechanical injection which shall run perfectly without electronics even. Electronics are for assistance and better performance. OVP doesny cause a sudden death of the Engine. Check the itema in my post from 1 to 3 and you will be Okay I m sure

 

[michel.s]

Klima is for the Airconditionning system. As for the fuel pump relay you probably wont see any cracked joint simply. You ll have to resolder all the relay.
If it was me i would make sure it s the relay before starring throwing parts.
A little and simple hint to identify a bad fp relay:
In bormal case when you turn ignition on you will here the fuel pump noise for 2 seconds and it stops then it will start when the engine starts, so what you have to do is when your engine dies. Try to cycle your ignition and listen carefuly if you hear that pump noise. If you dint hear it then it s the relay. If you hear the pump noise then the relay is not the problem.

 

[michel.s]

They can still be intermittent unfortunately.

Exactly. But since OP specified that the engine dont start up ditectly after dying and he needs to wait a little, if the realy is the problem it should not be running the pump during this waiting time. And again it may be the CPS since those get crazy when hot and once they cool off a little they will work again.

 

[michel.s]

So i guess you have many issues to solve here beside the relay.
First you need to make sure that the alternator is charging( you say that you have a battery light on) just test the voltage at the battery with a voltmeter. It should be between 13.5v and 14.5v when engine is started from cold.

Second, you need to inspect the ignition system since this is may exactly cause the symptoms you are describing and you previously said that it gets worse with humidity after wash. you have to inspect distributor rotor and cap conditions and HT wires. The HT wires may be inspected by parking the car in a dark spot and let someone rev the engine till it sputters and look for any electrical sparks around the HT cables that is escaping to the ground. If you find any then you have to replace the wires.

Those are the easiest to check at first. If those are good then we need to diagnose fuel and vacuum issues.

Concerning the fuel pump i personally never seen a tired fuel pump in this model that may cause a such problem it either works either no. Even if noisy. This may needs replacement but this is not necessarly your problem.

 

[michel.s]

Im sorry but what are HT wires?

Edit: I am assuming thats spark plug wires. I actually recently put in an order for a new distributor cap, rotor and wires; still waiting for the spark plugs to come in as well. Even if I didnt have this issue, I thought it would be a good idea to refresh those parts.

Yes those are spark plugs wires. You did right to place an order for those and i hope you ve choosen a good brand as there s a lot of brands in the market that wont even work. The most trusted and well known ignition brands are Bosch, Beru or Bremi.
For the spark plugs make sure to get ones without resistors. Bosch H7DC, H8DC or H9DC. And not HR7DC.. the R means resistor plug which doesnt work well with the w124.
The following can be also used if you dont find bosch ones:

1]Beru 14K-9DU, 14K-9DUO, or 14K-9DPU
2]Champion S12YC, or S12YCC
3]Denso T20EPU
4]NGK BP6EFS BP5EFS

 

[michel.s]

I have NGK BP6EFS coming in.
And I got Bosch replacement parts for the distributor cap and rotor. I got Karlyn-Sti spark plug wires.

You can replace the distributor cap and rotor with the Ht leads now and test untill you get your new spark plugs.
A little and fast job you can do at the meantine is checking the microfilter at the inlet of the fuel distributor. Give it a clean if it s not that bad or replace it. It should be part of a routine maintenance and it s often neglected along with the filter near the pump

 

[michel.s]

I dont really know if the carwash had any significance. I was able to start the car a minute after getting it out of the drive thru wash. The car had the same issues before and after the car wash as well.

I have ready signaled that and it may be a real sign of a cracked distributor cap. The synptoms doesnt necessarily improve when it s not humid but they will absolutely get worst with humidity. If you are that curious You can spray some water around the cap and see what happens. You may identify your problem that way if it s related to humidity😅