Author Topic: HELP  (Read 5505 times)

TOM250SL

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HELP
« on: July 10, 2021, 16:36:20 »
Good morning everyone.  I've been having problems with my '66 250SL for awhile now.  I sent it to my shop in Chicago in March, telling them it's been stuttering terribly on acceleration.  A few times it completely stalled out, but later it seemed to run a little better, but continued to stutter badly.  I got it back in June. They did a number of repairs, oil change, etc., and also sent the fuel injector out to be rebuilt and checked fuel filters.  When I got it back from the shop it ran great - for about 30 minutes.  Then began stuttering again.  I waited a few days and drove again, and it was worse - nearly stalling out.  Besides telling me to find a new shop, can anyone offer any insights?  To me it SEEMS like it would be related to the fuel system - fuel pump? cross-up with distributor? I have no idea as I'm not mechanically savvy.  I hate to have another summer without the car.  Any thoughts appreciated.  Thank you.

WRe

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Re: HELP
« Reply #1 on: July 10, 2021, 19:26:27 »
Hi,
I would suspect fuel supply too.
What about your tank and inside filter because of rust? Is there another filter between tank and fuel pump or blocked filter in fuel pump. Any interuption of power to fuel pump or air in the system. ....
...WRe

Pawel66

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Re: HELP
« Reply #2 on: July 10, 2021, 19:32:44 »
if you say you are perhaps not up to the task with fixing the car yourself, you probably need a recommendation for a shop in your area. I am sure someone will chime in.

Indeed this kind of trouble you described might be fuel related.
Pawel

280SL 1970 automatic 180G Silver
W128 220SE
W121 190SL
G-class

mdsalemi

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Re: HELP
« Reply #3 on: July 10, 2021, 20:09:18 »
Some suggestions based on my own experiences; things I lived with and figured out the hard way.

Check the wiring and integrity of the electrical connections to the fuel pump at the back of the car. Mine were once compromised which caused horrific intermittent driving issues.

Check inside the distributor to make sure nothing is worn and everything is in good condition inside.

Check the screens and the fuel filters as others have noted. The ultimate solution to one of my issues was replacing the fuel tank. As soon as that was done my problems went away. After 50 years or near to it, the inside of a tank rusts, creating a little micro particles which clog things. The new tank was costly but the problems went away.
Michael Salemi
Davidson, North Carolina (Charlotte Area) USA
1969 280SL (USA-Spec)
Signal Red 568G w/Black Leather (Restored)
2023 Ford Maverick Lariat Hybrid "Area 51"
2022 Ford Escape Hybrid
2023 Ford Escape Hybrid

Norm

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Re: HELP
« Reply #4 on: July 10, 2021, 21:05:50 »
I had the same symptoms that you described and followed a similar approach.  Plugs, wires, cleaned injectors, 123 Ignition, fuel filters.....  I finally replaced the tank and no problems after that.  It has been several years now.

My tank had been relined right after I got the car as a preventive measure.  So I was thinking it must be something else.  After reading a similar post from Michael that he posted long ago about his experience I figured it was worth trying.  Plus I had a new MB 280 tank installed which I had been thinking about anyway.

Good luck!

Norm
« Last Edit: July 11, 2021, 02:12:12 by Norm »
Norm
1966 230SL 162H Blue-Grey
1994 Acura NSX Formula Red
2024 Acura RDX A-Spec, White Pearl
2016 Mercedes S63 AMG Coupe Obsidian Black
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franjo_66

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Re: HELP
« Reply #5 on: July 11, 2021, 06:22:19 »
Hi Tom

I had a similar issue with my 230SL. Turned out to be frayed wires at the connection to ignition coil. So when driving any random shakes, bumps etc would cause reduced or no spark. Once I renewed the wires the random stuttering etc was gone.

Good luck and hope you nail the issue soon !
Franjo

1965 230SL Black/Auto/RHD
2005 Porsche Cayenne Turbo
1983 BMW 735i
1986 560 SEC
1991 500SL
1982 Holden Statesman DeVille

TOM250SL

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Re: HELP
« Reply #6 on: July 11, 2021, 13:09:00 »
Thanks everyone for your input on this.  These are all good thoughts.

Iconic

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Re: HELP
« Reply #7 on: July 11, 2021, 15:39:45 »
Tom,
I know you said you didn't want someone to state "get a new shop" .... but, you also said you are not too mechanical I believe. So, that doesn't leave a lot of options.
Have you talked with Mitch at Hi-Line European Automotive on Ogden in Downers Grove?
Also, what part of Chicago are you in? I'm in Highland Park.
You have not given us that much info as clues. There are many things that can do what you are describing. My own experience with a car shutting off on it's own led me to a clogged fuel return tube .... but gasoline is not a good thing to work with if you are not mechanically inclined. Your first steps should be to insure you have good "tune up" components and your throttle linkages are all adjusted properly. Then you should insure you have proper pressure and flow of gasoline throughout the entire system.
PM me if you would like to talk, also, if you take the car to Mitch, tell me and I would be happy to talk with him about it.
Good luck !
Mark
1970 280 SL Automatic, USA version, Grey-Blue (906G/906G), Blue leather (245)
1968 SS396 Camaro Convertible (owned since 1977 -- my first car :D)
1984 Porsche Euro Carrera coupe, LSD, SlateBlueMet/Blue
1998 BMW M-Rdstr Estoril Blue
1970 280 SL Automatic, Anthracite Grey-173G, Red Interior-132 - sold

TOM250SL

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Re: HELP
« Reply #8 on: July 11, 2021, 16:29:31 »
Hi Mark.

I live in Chicago - Gold Coast/Old Town, but I keep the car in Michigan.  Thanks a lot for your insights and especially suggesting Mitch at Hi-Line.  I've been going to H+M Autohaus and feel like I should take it back there one more time to see if they can rectify, but going forward I will definitely look into Hi-Line.  When I do I will PM you to discuss.

Also, I've attached a pic of my rear fuel pump.  Does anyone know if this is the proper model for a '66 250SL?

Tom

mdsalemi

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Re: HELP
« Reply #9 on: July 11, 2021, 16:59:46 »
Doesn’t look like a Bosch fuel pump. Wiring is exposed, insulation looks cracked.
Michael Salemi
Davidson, North Carolina (Charlotte Area) USA
1969 280SL (USA-Spec)
Signal Red 568G w/Black Leather (Restored)
2023 Ford Maverick Lariat Hybrid "Area 51"
2022 Ford Escape Hybrid
2023 Ford Escape Hybrid

Peter h

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Re: HELP
« Reply #10 on: July 11, 2021, 19:11:35 »
this is, for example, a short late pump.
Peter
08.68 280sl automatic white 717 G  blue MB Tex
09.68 280sl  4-speed, now 5-speed Getrag 180 G dark green MB Tex

Shvegel

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Re: HELP
« Reply #11 on: July 11, 2021, 21:16:51 »
That looks like a later Bosch pump designed for D- Jetronic injection.  Not enough volume and too much pressure.  Bob Youngman on Facebook or Baronyoungman here rebuilds the original pumps and may have a complete unit laying around.

stickandrudderman

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Re: HELP
« Reply #12 on: July 12, 2021, 07:24:37 »
That pump is a fairly regular mod and since the pump is gravity fed will only work if the pump is mounted lower than the fuel tank. Yours is not.
Try simply dismounting the pump and hanging it from a couple of cable ties to see if your problem is eliminated.

mdsalemi

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Re: HELP
« Reply #13 on: July 12, 2021, 10:53:51 »
That pump is a fairly regular mod and since the pump is gravity fed will only work if the pump is mounted lower than the fuel tank. Yours is not.
Try simply dismounting the pump and hanging it from a couple of cable ties to see if your problem is eliminated.

OR: put a proper Bosch fuel pump on, with proper fuel line attachments, a fuel pump cage, new pump mounts…do it right.
Michael Salemi
Davidson, North Carolina (Charlotte Area) USA
1969 280SL (USA-Spec)
Signal Red 568G w/Black Leather (Restored)
2023 Ford Maverick Lariat Hybrid "Area 51"
2022 Ford Escape Hybrid
2023 Ford Escape Hybrid

stickandrudderman

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Re: HELP
« Reply #14 on: July 12, 2021, 11:39:19 »
OR: put a proper Bosch fuel pump on, with proper fuel line attachments, a fuel pump cage, new pump mounts…do it right.
And miss the opportunity for a simple diagnostic check?
There's a reason I do this for a living. ;)

TOM250SL

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Re: HELP
« Reply #15 on: July 12, 2021, 12:18:28 »
First, thanks for the comments everyone.  As a '66 my car must have had the tall pump as original.  Will the later short pump work as well?

David Robinson

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Re: HELP
« Reply #16 on: July 12, 2021, 12:19:00 »
Hi Tom
Had a similar issue, but also had hot start problems. New pump sorted both. Do you have hot start problems?
David

TOM250SL

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Re: HELP
« Reply #17 on: July 12, 2021, 12:42:38 »
Hi Franjo 66.  Interestingly, I noticed that I can easily slide my ignition coil up and down within the stirrup that holds it in place.  Is it supposed to move like that?  Seems wrong to me, but don't know.  Based on your comment, this moving up and down may cause intermittent disconnections?

TOM250SL

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Re: HELP
« Reply #18 on: July 12, 2021, 13:29:06 »
Hi David.

Sometimes I have to actually hold the gas pedal to the floor on hot starts, but usually can get started - of course that was before the problems I'm having currently.

mdsalemi

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Re: HELP
« Reply #19 on: July 12, 2021, 13:36:29 »
First, thanks for the comments everyone.  As a '66 my car must have had the tall pump as original.  Will the later short pump work as well?

Yes, the short pump is a newer design and will fit. As others have noted, check with Bob Youngman here who has spent years working on a proper restoration of these pumps and having impellers engineered...
Michael Salemi
Davidson, North Carolina (Charlotte Area) USA
1969 280SL (USA-Spec)
Signal Red 568G w/Black Leather (Restored)
2023 Ford Maverick Lariat Hybrid "Area 51"
2022 Ford Escape Hybrid
2023 Ford Escape Hybrid

mdsalemi

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Re: HELP
« Reply #20 on: July 12, 2021, 13:47:56 »
And miss the opportunity for a simple diagnostic check?
There's a reason I do this for a living. ;)

With all due respect to you and the world's most famous mouse, hanging an improper fuel pump with cable ties is what we call "Mickey Mouse mechanics". Perhaps it's OK just to see if the gravity issue is at play here, but those wires have cracked insulation, the terminals are exposed, and this looks like a hot mess. I'd say rip it out and do it right. Is it worth spending so much time (which translates to money if you paying someone to do it) to diagnose?

On many cars of the era, people mistake electrical problems for fuel problems, and in one old British service guide for our old Austin Cooper, it said "Carburettor is a French word meaning 'It's the electrical system, stupid!'" However as we all know, NOT SO with the Pagoda. fuel pressure and fuel volume are critical. The injection system is a complex mechanical marvel. We all know there are a number of things that affect that, chief among them the fuel feed pump. Too often people are trying to take the least costly or cheap route to a solution instead of the proper route. You can mouse around with various fuel pumps, or you can bite the bullet and replace with a proper one. You can clean your screens and tank, and even have your tank coated or some such, but there's no substitute long term for a replacement. These are NOT cheap cars to maintain, and cheap solutions don't last.

No I don't do this for a living, but there's a reason why my 52 year old car is pretty well sorted. I didn't take shortcuts, for what its worth.

(Now that being said the next few months will tell all; the car hasn't been run seriously in several years...so maybe some work ahead of me...)
Michael Salemi
Davidson, North Carolina (Charlotte Area) USA
1969 280SL (USA-Spec)
Signal Red 568G w/Black Leather (Restored)
2023 Ford Maverick Lariat Hybrid "Area 51"
2022 Ford Escape Hybrid
2023 Ford Escape Hybrid

stickandrudderman

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Re: HELP
« Reply #21 on: July 12, 2021, 15:33:52 »
With all due respect to you and the world's most famous mouse, hanging an improper fuel pump with cable ties is what we call "Mickey Mouse mechanics". Perhaps it's OK just to see if the gravity issue is at play here, but those wires have cracked insulation, the terminals are exposed, and this looks like a hot mess.
::)

TOM250SL

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Re: HELP
« Reply #22 on: July 12, 2021, 18:26:52 »
Thanks Michael - I have reached  out to Bob.

TOM250SL

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Re: HELP
« Reply #23 on: July 12, 2021, 18:32:49 »
Today I went out and started the  car and moved/jiggled the ignition coil (or whatever that cylindrical part is that is attached to the side of the distributor cap - see photo in previous post), and noticed that when I moved it, the engine sputtered and would have died had I let it.  Not sure what exactly this means, but at a minimum I would think that part should not move freely . . .

Pawel66

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Re: HELP
« Reply #24 on: July 12, 2021, 19:25:51 »
It is a capacitor. It should not move freely. It is held by a screw. Try to tighten that screw and see what happens. This screw that holds it provides ground. The wire that sticks out of it should be tight as well.

If you spot more lose spots within the wiring around that area - tighten them.

Maybe you fixed it.

But take care of the fuel pump as well as suggested.
Pawel

280SL 1970 automatic 180G Silver
W128 220SE
W121 190SL
G-class

Shvegel

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Re: HELP
« Reply #25 on: July 12, 2021, 20:08:57 »
I would remove that screw before you tighten it.  It should be very short.  Less than an 1/8' of threads.  Any more and it will run into the internals of the distributor and break stuff.  It may be why it was left loose.

Pawel66

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Re: HELP
« Reply #26 on: July 12, 2021, 20:54:54 »
Certainly, great point form Shvegel, sorry, should have thought about it...
Pawel

280SL 1970 automatic 180G Silver
W128 220SE
W121 190SL
G-class

MarkCan

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Re: HELP
« Reply #27 on: July 12, 2021, 22:12:12 »
I got the 66 230 and 71 280 engine that I’m setting up at the moment.
The correct fuel pump for it would be the one in post #10. Unit you have currently is the newer version pump later used in the likes of w107 and early 126.
Before changing anything I would still follow Sick advice to confirm that this is really your problem.

franjo_66

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Re: HELP
« Reply #28 on: July 13, 2021, 00:16:55 »
100% agree with Pawel.
Attend to that loose capacitator. The fact that you have noticed the engine stuttering when you move it around is a good observation. Hopefully with this sorted and the fuel pump attended to, you will have many years of hassle free driving !
Franjo

1965 230SL Black/Auto/RHD
2005 Porsche Cayenne Turbo
1983 BMW 735i
1986 560 SEC
1991 500SL
1982 Holden Statesman DeVille

Shvegel

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Re: HELP
« Reply #29 on: July 14, 2021, 15:35:48 »
The ignition condenser (the thing on the side of your distributor) has a function.  It limits the current across the points when they open. Running without it or even having it be intermittent can burn the points in very short order.  I would strongly suggest having the points replaced even if they are nearly new.

For anyone deeply into Kettering ignition systems I know my description is an oversimplification.  I just didn't want to lose the point behind a bunch of theory.

TOM250SL

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Re: HELP
« Reply #30 on: July 15, 2021, 20:55:14 »
Update:
Thanks to all of your insights I think I'm on the way to solving my problems.  I'm changing out the condenser (MB original part - not off-brand) and points, changing all fuel filters, FOUND a rebuilt proper short-type fuel pump (thanks Bob Youngman).  Also thanks to Pierre Hedary who was kind enough to return my call and give advice.

TOM250SL

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Re: HELP
« Reply #31 on: August 15, 2021, 13:14:08 »
FINAL REPORT

I finally got my car back with correct rebuilt short fuel pump (thanks Baron Youngman and Pierre Hedary), condenser, points, plugs, etc.  It runs like a demon!  Better than it's ever run! Thank you everyone for your insights and input.  Still a couple of months of top-down driving to enjoy.