84 380sl Stalling/restart issue

[bradleykal]

Hi all,

Have a pretty consistent stalling and restart problem on my 84's 380sl. Usually after going down a pretty steep hill while the care is warming up, she'll decide to turn herself off, and takes about a minute of craning to get it to catch and restart. Also occasionally stalls when warm and under load - think 95mph in the fast lane on the LA freeway and the engine dies, pretty fun.

I've checked some of the electrical and removed an aftermarket alarm that was tied into the ignition coil. New fuel pump + filter. Pulled and cleaned air idle valve. checked for loose electrical connections, cleaned the connectors.

Kinda at my freakn wits end and making me very nervous about driving around town.

Next thought was the Fuel Accumulator as I understand that regulates pressure in the fuel system. Any ideas on how to test this easily? needless to say I don't have all to tools at my disposal and am pretty close to dropping it at my mechanic and making it his problem, but I do enjoy working on the car and trying to learn from it.

lastly, should mention I've had the car for 2+ years, this is something that's gone from intermittent to several times a week.
thanks in advance.

[gatopardo]

Hi: I just read your post. It reminds me of my own troubles with this condition. I spent two years trying to find out the cause, and went the same route you have followed. FINALLY, in this forum I read abouit the FUEL PUMP RELAY. It is behind the gopve compartment in my car(1988 560 SL). I did'nt want to spend money in maybe another wild chase, so I bougth a used one in the internet ($45). LO & BEHOLD, it worked. I have not have the problem again since the change. (3 months now) I was having the car stall on me at the rate of once a day. Anytime anyplace. So for what it is worth. This is my story. I hope it helps.

[bradleykal]

very interesting - I'll check out the part and see how much it costs. Is there any method to test if this part has gone bad? or is it just hit or miss?

One thing I did recently notice after reading about something similar in another thread - My gas tank isn't pressurized?? use to be, but now no hiss sound. Could be nothing.

[tecqboy]

Don't know anything about your 1st problem, but the pressure loss on the gas tank may be as simple as a bad rubber seal on the gas cap. They sell the rubber seal seperately. Found out mine was bad at an emmisions test when they test the cap to hold a vacuum seal.

[bradleykal]

appreciate the idea - just passed emissions several months ago, but will check it out all the same.

[meltedpanda]

My guess would be relay as well

what is the part number on that relay, I may have one laying about

[Lenny]

I had a similar problem with my 85 380. Does it stall often at idle? Does the engine surge and then die accompanied by an erratic tach reading? I replaced the ignition control unit (ICU)with fixed the problem. The ICU provides aan rpm signakl to the fuekl pump relay and tach. If this signal is compromised, bad things happen. The ICU on mine is to the left of the radiator inside the engine compartment,.

[meltedpanda]

I also have a ICU for an 83 - should be the same

[Gary Ratts]

I had a similar problem with my 85 380. Does it stall often at idle? Does the engine surge and then die accompanied by an erratic tach reading? I replaced the ignition switch (shop) that fixed the problem. Too bad I had to pay for all other attempts!

[samonline]

My car use to stall after driving it for few minutes (85 sl) . Check the fuses first. Second my problem was some rust sitting in the gas tank // I remove the gas tank , clean it with a pressure water and cleaner , put a red Kote in the tank and shake it all the way to cover all the rust in the tank , let it dry , change the fuel filter again ... and her she is ... rrrrrrrrrrrrrrrrrrr working again with no problems at all....

[bradleykal]

interesting... I always figured it for electrical, but it's been a long while since I've had it stall (knocking on wood).
I switched gas from Chevron to the BP up the street from me.... who knows. sure glad it stopped for the moment though!

[bradleykal]

FYI, re-read the posts - I had need to update as I have since replaced the Fuel Pump Relay (hooray for $100 random black boxes) after my mechanic spent a week looking for the problem. That did help decrease the frequency but not completely stop the problem. In the end, I'm guessing it was both electrical and dirty fuel.

[strelnik]

Originally Posted by bradleykal

interesting... I always figured it for electrical, but it's been a long while since I've had it stall (knocking on wood).
I switched gas from Chevron to the BP up the street from me.... who knows. sure glad it stopped for the moment though!

Boy you guys are great!

I have just saved a 380SL from being junked. It runs erratically and is not so much a victim of abuse as neglect in storage. Soon, after returning home, I'm going to go through the car and start cleaning things up to provide a base line for all future maintenance.

I've ordered and received a new oil filter, and I have been trying to get info on the car because it's a gray market 1984 out of Munich. I have the info from Germany on the data card, but I have no service records. I do know the main fuel filter was changed last year and only about 300 miles on the car since then.

If there's a thread specific to 380SL issues within the SL forum, you can bet I will be scouring.

I also found the chassis, air, maintenance and engine factory service manuals on paper.

Next quest is: what special tips and special tools apply to this car?
It's worth it to spend a little money and not break more parts than you repair!! I did discover how you pop the hood straight up for working on it, but that was a derivative of my work on older (1970) diesels.

I am mostly a diesel guy, originally non MB. My gas car experience has been on carbed Citroens from 1923-1975, especially the hydraulics, so Jetronic is not my strong suit.

Any/all threads, tips etc appreciated. I 'd like to contribute the fixes on this car as I do them, so we can have more SL DIY threads available to new users.
Thanks!

[450slcguy]

Originally Posted by strelnik

I did discover how you pop the hood straight up for working on it,

How is this done?