Need Help 1984-380SL Stalls/Quits

[jim16671836]

I have a friend that has a 1984-380SL that runs like a top and when the cars slows down to a stop or driving slow will idle at 12-1500 rpm. Then if the engine is shut down and you leave the car set for awhile and then when you return the engine will start and after driving for a couple blocks the engine will stall/shut down. Wait until the engine cools and it will restart and can be driven for hours. But the stall can be anywhere, on any highway...
thanks for any help... jim

[London380sl]

If it just sudeenly stops and can be started right away or in a few minutes
iIt sounds kike the ovp (overvoltage protection) relay which also might explain your high idle. THe OVP relay is located above the fuse panel in the passenger footwell. Do a forum search on "OVP" to get more info.

[Markjw]

A few years ago I had an 82 model with the same problem as yours. It turned out to be the fuel accumulator, this is situated near the fuel pump and is responsible for keeping the correct fuel presure in the fuel lines. These aren't on all models but it's worth a check.

[coleyjf]

Originally Posted by Markjw

A few years ago I had an 82 model with the same problem as yours. It turned out to be the fuel accumulator, this is situated near the fuel pump and is responsible for keeping the correct fuel presure in the fuel lines. These aren't on all models but it's worth a check.

I'd still check the OVP first - easy to change and often a fault cause especially tick-over/idle speed and loss of power.

Cheers

Jim

[SLovely]

I have almost exactly the same problem with my just purchased 1981 380sl. Starts and runs acceptably from cold but starting it when the engine has been warmed up is a struggle. When warmed up the car will stall at lights unless I put it in neutral and rev it up to about 1200.

What is the OVP that was mentioned and is it hard to acquire one? Sorry, I'm quite inexperienced with cars, but eager to learn! I've taken a look through some of the other mentions in the forum for OVP but am no wiser yet.

[Kyle Blackmore]

I've dealt with the same symptoms on my 85 380SE, I replaced the accumulator, injectors, OVP relay, coil, plugs, rotor & cap. It was still revving high (1200-1500) when warm. The accumulator solved the hard starting when warm or after sitting for a week. The rpm issue was never solved until my fuel pump relay gave up. A new one solved it but just this week it started to do it again. I need to go through all the ground points and confirm they're clean and tight.

[jim16671836]

After the car has been driven for 30 minutes the OVP gets so hot that it will burn skin when touched... What is the job of the Accumulator? Can the hot surface of the OVP be caused by a bad ground??? Jim

[Kyle Blackmore]

It sounds like the ovp is toast Jim, there's a fuse on top but I've never had one go. When I took apart my old one I couldn't see anything burnt on the board. I tried resoldering it but it didn't help.
The contacts maybe dirty in the plug, but it sounds pretty hot if it's burning your fingers, maybe an internal short that hasn't tripped the fuse?
The accumulator has a diaphragm that stores fuel pressure after the car is shut off. It's in line with the fuel pump at the tank.

[Kyle Blackmore]

Originally Posted by SLovely

I have almost exactly the same problem with my just purchased 1981 380sl. Starts and runs acceptably from cold but starting it when the engine has been warmed up is a struggle. When warmed up the car will stall at lights unless I put it in neutral and rev it up to about 1200.

What is the OVP that was mentioned and is it hard to acquire one? Sorry, I'm quite inexperienced with cars, but eager to learn! I've taken a look through some of the other mentions in the forum for OVP but am no wiser yet.

This could be several things from fuel pump to ignition, has the car sat for a while? My 380SE likes to be driven a few times a week, when it sat for a year being driven maybe once a month was when all my troubles started. It's a matter of testing components untill you find or suspect something. It gets expensive diagnosing by replacing parts The OVP relay is a cheap fix, easy plug n play install and usually stocked by any euro indy parts place or the dealer.
Good Luck