Starting/Running problems.

[R Binks]

Good morning.
I wonder if anyone can shed some light on the running of Pagoda SL 1964.
The list below shows what we have undertaken so far but have yet to succeed.
•   Petrol tank replaced
•   The petrol pump electric pump was replaced
•   The injection pump was serviced and tested.
•   Injectors were checked, and two were replaced.
•   Distributor replaced with 1-2-3 electronic replacement distributor system
•   Distributor cap, leads and spark plugs replaced
•   The coil was replaced four times ( advised to purchase a Bosch coil 0221 119 027 or 021, but impossible to find.
•   All fuses in the fused box are checked.
•   The ballast resistor was replaced.
•   Tappets reset.
•   The fuel filter was replaced.
•   Pressure test the fuel system (good)
•   Test fuel rate ( good)
Despite our extensive efforts, the car's engine exhibits unusual behaviour. It struggles to start, but once it does, it runs great. However, after a variable period of time, anywhere between 30 seconds to 20 minutes, the engine abruptly cuts out, as if the ignition has been switched off. There's no spluttering, it just stops.
 Then, when we try to start again after waiting around 10 seconds for the fuel pump to prime, it usually starts again and does the same.
We have also noticed that disconnecting one spark plug leads and usually starts on five cylinders!
We're truly grateful for any assistance you can provide. Your expertise and guidance would be greatly appreciated.

[Cees Klumper]

It may not be at all your issue but a few years ago, my 280SL would randomly cut out while driving. I found the cause to be one of the two small wires that connect to the coil to provide its signal had a slightly loose crimp connection (I made that faulty connection myself at some point) so although it seemed to be connected, it wasn't connected 'enough'. Re-crimped and soldered the connection and it's been fine since. My point being that although you replaced many 'usual suspects' components, the fault could well be in the wiring/connections/grounds and could be very hard to detect if it is a partial break inside wire insulation. Given what you describe, this is where I would focus my next efforts if this were my car. Best of luck, I am sure others will chime in as well with their thoughts.

[R Binks]

Many thanks for the advice, we have cleaned all the earths and connections  and still have the same problem! it has us baffled.

[Peter van Es]

The ignition switch itself?

[BobH]

It looks like you need to work through everything and rule them out, electrics, fuel etc.  Have a read through the technical manual above left, everything you need will be in here

This is a good starting point, but you'll need to register as a full member to access these pages

https://www.sl113.org/wiki/Restricted/Engine-starting-aid-tour

There's also write ups on 123 ignition (I understood the ballast resistor needs to be linked out?), correct replacement fuel pump and mounting height, timing, injection system and pump, starting aids, ignition switch, etc etc

Good luck and please feed back what you find and any more questions

[R Binks]

Thanks, will definitely look into the switch.

[R Binks]

Many thanks for the advice sounds like a good plan of action, hopefully report back with a positive outcome.

[ctaylor738]

Suggest:

Ground the 123 using the threaded hole on the bottom of the housing.

When trying to re-start, connect a timing light to see if there is spark while cranking.

Immediately after the engine dies, run a fuel volume test.

CT

[Pawel66]

Immediately after the engine dies, run a fuel volume test.

CT

Fuel volume test. I am not a mechanic, just went through a lot of similar issues with the help of Forum here.

One if the key learnings I took away from it is that erratic engine work and starting difficulties (particularly warm starting) are very often result of clogged fuel system. And fuel volume test (measuring flow at the end of return line) is a very simple test that can tell a lot. Close to 1 liter in 15 seconds, not less than 0.6 - 0.7 liter in 15 seconds may tell you if fuel goes through the system or the engine is starving.

[clunker]

"•   The ballast resistor was replaced."

If you installed 123ignition the ballast resistor is no longer used - it should be bypassed, with the wire from the ignition (from contact 15 on ignition switch) going direct to the coil. If you still have that in series that may be an issue.

I second adding the earthing strap to the M5 hole on the bottom of the distributor.

I also could not source the Bosch coils (was looking for red) - I used a Pertronix 40011 1.5ohm successfully.

Also, you note it cuts out immediately as if shut off, no stuttering to a halt - may this not suggest it an ignition / electrical connection issue rather than a fuel issue?

[R Binks]

Thanks for the information.

[R Binks]

Cheers, i will look into that.

[R Binks]

We are definitely thinking that it is most likely an ignition / electrical connection issue, and we haven’t  bypassed the ballast resistor, so we will look into that 1st plus the earth on the distributor. Many thanks

[rwmastel]

•   The petrol pump electric pump was replaced
•   The coil was replaced four times ( advised to purchase a Bosch coil 0221 119 027 or 021, but impossible to find.

Which electric pump and which coil did you use?

As Cees said, just because the wire clamp is tight on the post, it doesn't mean it's tight to the actual wire.  My Jeep had that problem with a main + battery cable.  Previous owner connected extra accessories there and put it in nice heat shrink wrap.  I couldn't physically see the disconnect, cable was tight to the battery post.

[franjo_66]

Many thanks for the advice, we have cleaned all the earths and connections  and still have the same problem! it has us baffled.

i had the same exact issue and once it was sorted it runs like a champ

[R Binks]

Good morning,
Many thanks for replying.
We have fitted two Cambiare VE 520004 ignition coils and currently have fitted a Magneti Marelli BK 2 ignition coil.
The fuel pump we have fitted is a Bosch 0580 464 200 which we were advise to use.
We are looking into all the suggestion to try and find a solution.
Thanks

[Vander]

The fuel pump you mentioned is not for a Pagoda and is a high pressure pump. Your car would have originally come with 0442200007, although when replacing almost all early W113 owners switch to the Bosch short style pump found on the later 280SL.  Bosch Part # 0442201002

[Pinder]

for 123 ignition. bypass the ballast resistor.   Also check the ground connection from Battey to frame. (I had this problem where car would randomly die).

I have sucessfully used the following fuel pump as a backup. its about the correct PSI.  Carter Fuel Systems Electrical Fuel Pump Automotive Replacement 12V (P4601HP)

https://www.amazon.com/gp/product/B000CIU8I4/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1

[Pinder]

also make sure the engine/ transmission is grounded by the copper cable to the body of the car properly

[Cees Klumper]

I've run my 123 ignition with and without ballast resistor for extended periods and noted no perceptible difference. I finally went without as per 123 mfg instructions but I don't think this can be your issue.

[rwmastel]

R Binks,

I am glad you found our forum and welcome to the Group.  You have done quite a lot of work, replacing many parts.  Was this all in an effort to solve this one problem?  I hope you're working with a well respected mechanic with reasonable experience in 1960's Mercedes.  Regardless, I'm sure our members can guide you to a resolution.  The problem should be electrical, as we all seem to agree on.  The ignition switch to the coil, it could be anything along that path.  Troubleshoot with a multimeter, giggling wires, looking for poor connections.  How is the wiring in general?  Still factory original and correct?  Or, has a restorer been at work, or someone modifying for a car alarm, big stereo system, or other accessories?  Have mice been at work?

[R Binks]

Good morning,
Sorry for not acknowledging your posts. We have been busy reviewing the list of explanations and are still processing them one step at a time.
Thus far from the list, we have cleaned all the earths, changed the coil and bypassed the ballast resistor ( no difference still cuts out), but the spark at the plug seems more robust; we added an earthing strap to the bottom of the distributor.
We undertook a fuel flow test on the return line and obtained 1 litre in 15 seconds, which is well within the expected parameters.
Charles mentioned bypassing the wire from the ignition (from contact 15 on the ignition switch) and going directly to the coil, which we plan to look into.
Many thanks for your responses. It is much appreciated, and any other advice would be valued.
I think the next step is to check the wiring!!
We're genuinely grateful for the assistance you have provided
and will keep you updated.
Kevin

[clunker]

if you have bypassed  the ballast (connect wire to coil to 'other side' of ballast resistor, same side as ignition supply wire) then you have accomplished the bypass - nothing further to improve there. Checking cabling /contacts for fault/looseness seems a best bet.

I also note that with this sudden cutoff happening at some unfixed point after successfully starting, something may have warmed up/ become active such as a temp sensor etc - check cold start / WRM etc circuits as well, or any extra temp sensors your set up may have - they may somehow short when heated up.

[clunker]

Also, another thread in electrical forum gave me a thought - do you have any radio interference capacitors still connected in the ignition system circuits? If one fails when getting charged up (at inconsistent intervals) then a failure mode could possibly cause a short in the ignition system…

[ja17]

I don't see that you did a fuel pressure measurement only the volume test?