A little help, please! - PeachParts Mercedes-Benz Forum

Marc · #1 03-17-2012, 07:05 PM

Hi,
I have an 83' 500sl euro. The car has been running fine. Today it stalled driving thru town. I was able to get off to the side but, the car wouldn't restart. It would crank and sound like it was going to start but would stall again right away. I was on my way to pick up my daughter so, I decided to walk the rest of the way. By the time I got her and we walked back, the car had sat for about an hour. It started right up. I was able to drive maybe 6-7 miles and the same thing happened again. Would try to start then stall right away. If I waited 10-15 minutes it would start and I'd get maybe a mile or two. Then same thing. So, it took awhile but I got it home. Let it sit for an hour or so. Runs great for maybe 5-6 miles. Then same thing starts again. I'm guessing it must be fuel related. Fuel pump, accumulator, maybe? Anyone else had these symptoms? Just to clarify. When I say tries to start. I mean it doesn't just crank but does fire off and then stalls. I can tell when it is actually going to run because the rpms will go up and then come back to idle as typical fuel injection does. Don't know how else to describe this.
Unfortunately, I have to depend on this car at the moment so I've got to get it fixed quick.
Any assistance would be greatly appreciated.
Thanks again

Marc

joselu43 · #2 03-17-2012, 10:15 PM

Had the exact same thing happen to me. Fuel pump relay. I now always carry an emergency "wired" FPR in the glove compartment. Easy fix. Could be other things, but that is my bet.
If that turns out to be your problem, check you fuel pumps.

Jl

Marc · #3 03-18-2012, 12:21 AM

Thanks Jl
I have wired the relay. The fuel pump runs as soon as I plug it in.
It's late here but I will test it tomorrow. If this resolves the issue that would indicate that the relay has failed. You mentioned in your post "If that turns out to be your problem, check your fuel pumps" did you mean to say "if that turns out to NOT be your problem" or are you saying to check the fuel pump as well? I did replace the fuel pump probably 8-10 years ago. Up until the last few months the car has been rarely driven. Like less then 500 miles a year. Are you then saying that the fuel pump may have caused the relay to fail? Or is it more just a matter of time?
Thanks again. Appreciate your help

Marc

joselu43 · #4 03-18-2012, 01:17 AM

I do mean check the fuel pumps. There are many a reason for the relay to fail. One of them is one or both pumps drawing too high a current. There are many others causes but I would check that first. If it is one of the pumps and you do not replace it, it is a matter of time, but the relay will fail again, trust me.

Jl

rowdie · #5 03-18-2012, 10:55 AM

You one have one fuel pump on the '83 500SL. And yes if the fuel pump is over heating or drawing too many amps. for what ever reason it could cause a relay failure.

RadioTek · #6 03-18-2012, 02:51 PM

If a car has been driven rarely, it is not unknown for there to be rust deposits in the fuel tank. These could be blocking the filter inside the tank, and probably the main filter as well. I'm not saying this is your problem, merely a possibility to check out.

Good luck,
Scott

tecqboy · #7 03-18-2012, 10:07 PM

I don't know nuttin' about the engine in your car. But if it has a crankshaft position sensor, check it. They fail when hot and then work again when they cool down.

Marc · #8 03-19-2012, 09:15 AM

I jumpered the pins on the fuel pump relay and the car has run without issue. I had noticed that the car was cranking longer before starting before this issue occurred. After jumpering the pins the car starts right away. The fuel pump does not seem to be warm when I get back after using the car, the relay is when I remove it though. Although I have no idea of knowing if it usually runs warm or not. At this point I'm going to just replace the relay and hope for the best.
I do thank you and appreciate all of the help and quick responses.
Marc

joselu43 · #9 03-19-2012, 02:09 PM

The only reliable way to check the pump is to measure the current draw. Good luck.

JimFreeh · #10 03-21-2012, 06:36 AM

Quote:

Originally Posted by Marc

I had noticed that the car was cranking longer before starting before this issue occurred. After jumpering the pins the car starts right away.

This suggests that you also have a failing check valve.
Fuel pressure is bleeding off after shutdown.
The relay will shut down the pump if it detects no crankshaft movement, so you can hear the pump run for a few seconds when you turn the key, then the pump cuts off until you start cranking.
When you jump the pins, the pump continues to run, building pressure.

Jim