83 380SL Sputtering Until Warm - PeachParts Mercedes-Benz Forum

Kimolaoha · #1 04-13-2009, 10:12 AM

Hello all:
Our 'rarely driven' 83 380SL "winters" in the driveway with a Deltran smart battery tender, and has always started right up and driven well. Last use was back in February when my daily driver was in the shop and the SL was pressed into service. Ran just fine.
This past weekend, I discovered that the battery (at the end of its sevice life) had finally gone south. I was able to jump start the car, but the battery would not hold a charge so it was replaced.
Now, however, the car starts right up, but after a minute or so, loses power, bucks and misses, etc. until I can coax her up to operating temp, at which time she runs OK, but definitely not as smoothly as usual.
I do recall that when I was attempting to jump the car, some type of "event" occurred where I temporarily lost ALL power (i.e. all electrical systems shut down) as if I had blown some sort of fuse or fusible link (scary) but then the electrical system "came back" and took a jump and all seemed well until the missing began.
The tank was about 1/4 full and I initially thought water had condensed in the tank, so I put a couple bottles of dry gas in and filled the tank, but the problem persists at every startup after the car has been sitting any length of time.
Any ideas? OVP? Since the car starts right up when cold, I'm thinking the warm-up regulator is probably not the culprit?
Thanks
Mike

meltedpanda · #2 04-14-2009, 10:18 AM

sounds fuel delivery related, are you getting any smoke - white /black? Have you pulled a plug to look at tip? If your cold start valve is working perhaps after it gets its first shot of gas the injectors are not functioning as they should. Pretty easy for them to gum up if not driven. Once warm , does it start easy?
Need a little more information, but definitely check fuel pressure, and check for sticking throttle plate

Kimolaoha · #3 04-14-2009, 10:18 AM

Quote:

Originally Posted by Kimolaoha

Hello all:
Our 'rarely driven' 83 380SL "winters" in the driveway with a Deltran smart battery tender, and has always started right up and driven well. Last use was back in February when my daily driver was in the shop and the SL was pressed into service. Ran just fine.
This past weekend, I discovered that the battery (at the end of its sevice life) had finally gone south. I was able to jump start the car, but the battery would not hold a charge so it was replaced.
Now, however, the car starts right up, but after a minute or so, loses power, bucks and misses, etc. until I can coax her up to operating temp, at which time she runs OK, but definitely not as smoothly as usual.
I do recall that when I was attempting to jump the car, some type of "event" occurred where I temporarily lost ALL power (i.e. all electrical systems shut down) as if I had blown some sort of fuse or fusible link (scary) but then the electrical system "came back" and took a jump and all seemed well until the missing began.
The tank was about 1/4 full and I initially thought water had condensed in the tank, so I put a couple bottles of dry gas in and filled the tank, but the problem persists at every startup after the car has been sitting any length of time.
Any ideas? OVP? Since the car starts right up when cold, I'm thinking the warm-up regulator is probably not the culprit?
Thanks
Mike

PROBLEM RESOLVED -

For those that may run across this thread in the future, my issue turned out to be the 25 cent 10-AMP ATC Fuse in the overvoltage protection relay (OVP). I suspected this to be the case because of the odd "burp" that occurred when I was jumping the battery over the weekend.

It is amazing (but not necessarily surprising) how poorly the car runs when the OVP has disabled the various fuel/ignition boxes. The car would start fine but bog down badly after a minute or so -- to the point that it was dangerous to even try to pull out onto the road. After it warmed up a bit -- say five minutes -- it would accelerate, albeit poorly, and it was still missing badly. If it did stall, though, I never had any problems restarting.

For those looking for it, the OVP (at least on an '83 SL) is in the front passenger's footwell, behind the kick panel just forward of the door, and slighly below the glove compartment. If you remove the fuse panel cover, you MAY be able to barely see it at about the 2 o'clock position, but it was not (for me) accessible through the fuse panel cavity, and I had to remove the "permanent" kick panel to get access. It MAY also be accessible through, or after removal of, the glovebox cavity.

I happened to have a spare OVP from an earlier troubleshooting exercise, and simply pulled the 10-amp fuse from the known good OVP and popped it in the installed OVP -- so it seems that the installed OVP was not fried -- just the fuse. I plan to start carrying a spare 10-amp fuse in the car -- if not the spare OVP itself.

One can only wonder how many hours and dollars have been spent by unsuspecting owners trying to chase down the drivability problems caused by a simple 10-amp fuse.

Beware when jump starting from or to your car's battery, as the blown OVP fuse appears to be a common result. But I do take comfort in the fact that the OVP does exactly what it is upposed to do, and possibly saved some of my high dollar black boxes! I'm glad to have resolved the issue.

Good luck.
Mike

nomorehurry · #4 05-05-2013, 03:54 PM

The information is still valid and appreciated. Thanks

nomorehurry · #5 05-06-2013, 02:48 PM

Meltedpanda, Sorry, but I have not done much of anything yet. I don't want to dig too deep until I get the service manual - about a week from now.
From my reading, I see the possibilities as the OVP, the temperature senser, a vacuum leak, or gremlins. I just replaced the battery so I am assuming the previous owner had to jump start the car and warm it up before I got there to look at it, so the OVP is a strong possibility.

meltedpanda · #6 05-06-2013, 08:30 PM

no worries, keep us posted

nomorehurry · #7 05-22-2013, 08:55 PM

I received the MB service manual for the 107, so far it hasn't helped much on the idle problem. It may be the OVP; I found where it is and can see it (I think) but can't get to it yet. Where is the fuse for the OVP? I think I have to remove the complete side panel to get at it. (Better check the CD manual.)

I have been working on the AC system. I need a new compressor and a new CCU

. I did use one of the DIYs to recondition the auxillary water pump, and I did put a fuse on the power side. I found the best choice to be a 1 or 1.3 amp slow burn in line fuse. On my 300Dt, I kept going through fuses because the start-up power would pop the fast-burn fuses.

When I do get around to the compressor, I intend to replace the antifreeze (it is green) and all of the belts at the same time since I have to pull the radiator anyway. Suggestions for additional stuff is welcome. The smog air pump is also toast (wire cut) but that can be replaced without pulling the radiator and will have to wait. This car is definitely not going to be a short term project.

nomorehurry · #8 05-22-2013, 10:19 PM

UPDATE: I finally decided the service manual on CD didn't have the information I wanted, and told myself to GOMSA (Get Off My Silly A$$), and started taking off pieces until I could reach in and pull the OVP. Sure enough, the fuse was toast. Being sure I didn't have one of the correct size, I roamed the garage and workshop. I do have a 10 amp fuse in the trailer, but it is in storage behind armed guards (on base). Surprisingly, I found one in a box, put it in, said hopeful words, started the car, and drove out of the garage without stalling or anything going boom. I am much happier now!!

(As I have said many times, Thanks to all who contribute to this forum. The information is invaluable!)