380SL Sputters & loses power. Restart solves problem. - PeachParts Mercedes-Benz Forum

Zestieboy · #1 04-01-2006, 03:29 PM

Hi All:

Thanks in advance to any help with this oddball problem. I recently bought an 83 380SL. It has the double roller conversion and 88,000 miles. Cherry car... except: After about 45 minutes of highway driving, it begins to sputter and jerk (kinda' lunges) and lose power - acts like a fuel starvation problem. It happens sooner if the car has been "pushed" like driving on hilly terrain. It also happened more frequently and sooner these past few days as the temps have risen in the northeast leading me to believe I'm in for a lousy summer driving experience. Thing is... if I pull over, stop the engine and restart, it all goes away... almost like something is "resetting". Everything goes back to normal only to return again a while later. Everything else is normal and the car drives as new otherwise. I alternate adding a can of Ventil Sauber and Jectron once a month. Within the last 3,000 miles, the tank has been dropped, flushed and cleaned, it has new fuel filters, air filters, wires, distributor cap, and brand new injectors. Any ideas? Thanks!

Roncallo · #2 04-01-2006, 05:26 PM

Quote:

Originally Posted by Zestieboy

Hi All:

Thanks in advance to any help with this oddball problem. I recently bought an 83 380SL. It has the double roller conversion and 88,000 miles. Cherry car... except: After about 45 minutes of highway driving, it begins to sputter and jerk (kinda' lunges) and lose power - acts like a fuel starvation problem. It happens sooner if the car has been "pushed" like driving on hilly terrain. It also happened more frequently and sooner these past few days as the temps have risen in the northeast leading me to believe I'm in for a lousy summer driving experience. Thing is... if I pull over, stop the engine and restart, it all goes away... almost like something is "resetting". Everything goes back to normal only to return again a while later. Everything else is normal and the car drives as new otherwise. I alternate adding a can of Ventil Sauber and Jectron once a month. Within the last 3,000 miles, the tank has been dropped, flushed and cleaned, it has new fuel filters, air filters, wires, distributor cap, and brand new injectors. Any ideas? Thanks!

Well 45 minuts seem to be too long for a fuel filter but its cheep enough to try. A heat related electrical problem, like an ignition module would usually require a long cool down to reset.

Good Luck
John Roncallo

page62 · #3 04-01-2006, 08:14 PM

Fuel pump. It sounds it's overheating.

Zestieboy · #4 04-01-2006, 08:57 PM

The odd thing is that all I need to do is shutdown and restart the engine and it's all gone. There's no waiting time involved in letting anything cool off. Yesterday, I never stopped - just threw it into neutral shut down restarted and went on my way. It sounds to me like it's caused by a sensor somewhere that resets when the car starts. Now what that is is another story.

Roncallo · #5 04-01-2006, 09:51 PM

If you have a fuel pressure gage drive it with it installed and see what happens.

John Roncallo

Bondavi · #6 04-01-2006, 11:17 PM

Sometimes the impeller bearing in the fuel pump drive mechanism will overheat and bind to the magnetic rings. Turning it off then back on will remedy this, only to have it happen again at another time. Especially if the pump is overworked due to a dirty/clogged fuel filter. Worth a try.

ctaylor738 · #7 04-02-2006, 06:52 AM

I would try jumping 30 to 87 on the fuel pump relay, drive it, and see if that fixes it. If it does, replace the relay.

AF300E · #8 04-02-2006, 08:54 AM

Also, If you jump those pins with a multimeter it should tell you if the fuel pump is working too hard depending on the current draw.
I think it should draw less than 7 amps. I sure someone will have the correct draw rating if I am wrong.

Don't discount the relay idea though. In the 380sel I had, it would stall, then not restart for sometimes 1, sometimes 10 tries. Then all of a sudden, it would start and run like nothing had happened. Thankfully by then I had had some fuel pump relay experience and after resoldering the relay it solved the problem.

Zestieboy · #9 04-02-2006, 03:13 PM

Some great ideas. My next steps are to hit the fuel pump and the relay hard and see what happens. Thanks for helping.

BELLA1 · #10 07-03-2006, 08:32 AM

I Have The Same Problem, Did You Ever Find The Fix.

Zestieboy · #11 09-22-2006, 07:48 PM

Still looking. Replaced the relay and the OVP relay too. - - nothing.

BIGRED3 · #12 09-22-2006, 08:55 PM

Hey, can someone help me I have a 1987 190E. When i stop @ a stop sign or in traffic my car stalls. I have no problems driving down the road, just stopping. Any ideas?????

Zestieboy · #13 09-23-2006, 08:41 PM

Here's an interesting discovery in my problem: The stalling, sputtering no power problem completely disappears when I fill up the tank. As long as the tank is more than 1/4 full, I'm OK - runs like a dream. At about 1/4 it starts happenning infrequently but then as the gas level in the tank continues to drop, it gets really bad.

Now I know there is supposed to be a certain amount of tank vacuum produced by these MB closed systems. Every other car I have ever owned makes a "whoosh" sound when I open the gas cap - this car - nothing at all. When I got it, it had a generic vented gas cap. Now since I know MB isn't vented, it replaced it with the correct non-vented MB cap. Did I make the problem worse by doing that? Also, assuming this tank vacuum / gas level clue is meaningful, what does this tell me? Have I stumbled upon something here or is this ongoing intermittent fuel starvation issue finally driven me crazy?

Zestieboy · #14 09-26-2006, 05:32 PM

I've now confirmed that the fuel level is a direct clue on the problem. Three times since my last post I got the problem to start and become chronic as the gas ran down only to disappear when I re-filled the tank. I also tried using the old vented gas cap and using no cap at all and neither one had any effect. And no matter what the situation or circumstances, I NEVER hear a sound when I remove the gas cap.

It's difficult for me to explain this as an ignition problem anymore. I'm also not sure how the FPR impacts this anymore either, but I'd like to make sure by getting the problem to manifest itself and then jumpering the relay. What pins do I jumper to test the FPR once and for all?

Assuming the FPR checks out OK and that the FP and filter are new, where do we go? FP check valve, FT vent valve, accumulator, screen, damper, warmup (control pressure) regulator, fuel distibutor?

If this weren't such a PIA, I might actually be fun!

Thank you all for your excellent suggestions, time, and interest in my problem.
Ray

ejboyd5 · #15 09-27-2006, 08:15 AM

See my reply over on the MBCA site - in short, look for a crack in the fuel pick-up line somewhere around the 1/4 fuel level in the tank.