ChamaRiver

My 500sel fires on initial try, but dies. Then have to use starting fluid to get it to fire up. Once car warms up it runs and starts fine. Any ideas what could keep it from starting right up on first couple cold start tries?

Also, the car does not hold steady idle, it fluctuates up and down, and will stall-out when it goes down to 500- rpms.

The shop mechanic broke off the Fuel Distributor Air Flow Meter Adjustment unit because it was striped inside. I bought a new one and installed it, and adjusted best I could. He also replaced my fuel filter and plugs. But I still have the same issue with the car not starting without starting fluid. So whatever was wrong before is still the issue now. Cost me $550 to be in same spot.

RyanRichter

That sucks.

You have a cluster f**k problem.

Adjust the flow meter after you get it running with starter fluid.

After adjustment, pull the fuelpump relay and take note of any changes. If no changes, check the OVP (overvoltage protection unit/fuse)

The top of the OVP has a #10 fuse in it. Pull and check to see if its burnt out.
Replace if burnt out. Then remove full unit, take note of any changes. If no changes, check your coldstart valve.

Go thru these first and if there is no change, We can try some other options.

Ryan

ChamaRiver

Hi Ryan, I got the car started and then adjusted the fuel enrichment at the best (smooth) running position. When I pull the fuel pump relay the engine stops running. I had a backup fuel pump relay and tried it and the same thing happened. I checked the fuse on top of the OVP and it is good. I will try to start the car later today after it cools down to see if it will start cold. At this point the engine only fluctuates slightly, but it is warm now.

RyanRichter

Sounds like you might just be running lean on the coldstart.

ChamaRiver

Is there an adjustment, or do I need to change the cold start valve? I have a spare. But it looks like there is one valve near the rear of the engine and another near the front of the fuel distributor.

RyanRichter

Im pretty sure you can adjust it, and I dont know if yours has 2. I really only know the m103/m104 motors.

Ryan

ChamaRiver

Ryan, There was no adjustment on the cold start valve. I did adjust the fuel enrichment a little more and was able to get the car to start with out starting fluid. But idle is down to 500, and dies occasionally when it dips below that. I noticed a strange thing, when my car idles the needle on the "Economy" gauge is in the red (about at the half way point on gauge), and pegs the top red area with just a little pedal. But the car runs smooth, except the idling/start issue.

RyanRichter

Your right! I checked my coldstart after I sent that and found that I had lied to you! sorry!

My motor does that when The OVP is on the fritz! when its running pop the OVP out of its little holder. manualy throttle the motor and tap the OVP against the sheet metal. if it clicks over and runs better then REPLACE the OVP!

Ryan

ChamaRiver

Ryan, I pulled the OVP while the car was running and the engine did not stop but did appear to idle smoother and did not fluctuate up and down. When I put the OVP back in the engine accelerated at first then idled down and went back to idling with a slight fluctuation. Rapped the unit on solid surface also. The fuse is good.

ChamaRiver

Ryan, I ran out and removed the OVP and started the car, it started without the OVP installed, but noticed the idle was now at 1,100rpms. I revved it up and the engine again came back to 1,100rpms and idled smooth at that high idle. Is there any way to test this OVP?

RyanRichter

Not sure why the motor would run smoother. It still sounds like the OVP is bad.

I dont know how to test it any further than to find a working used OVP and trying it. That or buy a new unit.

Ryan

ChamaRiver

I got the new Overload (Voltage) Protection Relay and installed today. As soon as I started the car it idled for about 5 seconds then shut down. Just like someone turns off the key. So the OVP was not the answer.

Also, I have to hold the petal down a little when fist starting from sitting all night for it to start and hold without immediately dieing.

Once the car has been warmed up it starts and idles (usually) ok, though sometimes the idle runs at around 1200rpms, when normally the idle is at 750rpms. And when driving the engine runs very smooth.

RyanRichter

so my 300 was doing the EXACT same thing. runs poorly wont start or start lit i replaced fule relay and ovp and a host of other things. i still have to hold petal on a cold start. so im stumped! i hope the ovp wasnt too hard on your wallet.

ChamaRiver

Hey Ryan, no problem, can always use an extra to put in the truck just in case it is needed one, these do go bad.

Obviously the problem has to do with cold starting because once the car has warmed up it starts normally.