Possible fuel injector Issue

[vouker]

Hello All,

I just joined this forum as I have a question to ask: My 230SL has recently stopped working. Here's a brief timeline.

Recently, (a few months ago), the car started sputtering a little bit, as if it was running on 5/6 cylinders. I thought this was a timing issue, and looked at the timing, and set that up correctly with the help of a mechanic. After that, the car ran for a week or so, but then just didn't start one day after I had parked it.
I re-checked the timing, and made sure it is correct, using a timing pistol and the mark on the crankshaft and rotating the distributor accordingly.. I also removed the rear fuel pump under the tank, cleaned it, and re-fit it, and it works well. There is good fuel pressure all the way to the engine bay, and after checking the California emissions system tube, I noticed that there is normal pressure there (gas was squirting straight out of the pipe).
I then proceeded to detach the fuel line from the injection nozzle, and noticed that in all the cylinders, there is sub par pressure, and gas seems to be dribbling out when the starter is engaged. I am wondering whether this could be due to the fuel injector not being calibrated correctly, or if something else could be failing.
It is not an electrical issue as I checked all the spark plugs and they are firing correctly. I will also try to take a photo to upload a little later so I can illustrate my problem.

Please excuse my lack of deep knowledge on mechanics of the car!
Any help is appreciated!

[ja17]

Check to make sure the ignition points have not closed.  Remember if you have spark on time, compression and adequate fuel supply and volume, the car will start. How do the spark plugs look?

[vouker]

Ja,
Thanks for the tip.
The ignition points are fine (I assume you mean the part under the distributor cap), and the spark plugs have each been removed, cleaned, and they all spark correctly when I engage the starter. I'm 99% sure that it's a fuel issue as there is not adequate fuel going to the cylinders. There is a small screw that can be turned with your fingers on the back of the injection pump, which I think regulates the amount and the pressure of fuel that goes to the cylinders. I was wondering if I should maybe tamper with that thumb-screw or not...

[ja17]

The thumbscrew on the IP only adjusts mixture at low rpms. You might try turning the ignition on, then energize the intake starting solenoid with a jumper wire for a second then see if it starts. If it does this will signify lack of fuel from the injectors.

[vouker]

Ja,
Thanks for your response,
However I don’t know where the intake starter solenoid is! (New owner problems) could you help me out with where it is located/what it looks like?

[Benz Dr.]

There won't be very much fuel coming out of your disconnected fuel lines at starter speed so I wouldn't use that as any sort of gauge to determine if everything is working. You will want to see fuel coming out of all of the pipes but it's very difficult to tell if you have enough or not.
If you have enough fuel pressure and volume your engine should run. There can be a number of other problems that can result in a poor or no running condition but I would start with the basics first. 

[Pawel66]

The thumbscrew on the IP only adjusts mixture at low rpms. You might try turning the ignition on, then energize the intake starting solenoid with a jumper wire for a second then see if it starts. If it does this will signify lack of fuel from the injectors.

vouker, by "intake starting solenoid" or "Cold Start Valve", we mean what I circled on the picture. It is called "Cold Start", but it works and is important for warm start as well. It is a solenoid activated valve that injects additional fuel to the intake, independently of the main 6 injectors, to give engine more fuel for start. If you energize a solenoid of this valve to inject fuel and engine starts at least for some time, it will prove your theory about fuel lines and injectors being wrong. But if engine does not start and you are not sure if this solenoid/valve work correctly, do not draw any conclusions as the CSD may not work or it may not be getting fuel.

[vouker]

Pawel,
Thanks for pointing that out.

That system was what i mistakenly called the “california emissions system” in my original post. Gas comes out of there with good pressure so I used that as a benchmark for what the other lines should have as pressure. I’ve completely bypassed that system since I first got the car a few years ago and it used to not have problems. I’ll try reactivate it and see how it runs.
Thank you all for the support, and if you have any other ideas, please feel free to drop them off!

[Pawel66]

Do not compare amount of fuel delivered. As Joe said, the amount you receive from injectors while cranking is a few drops. The CSD gives you a fair squirt as fuel there is under pressure from the fuel pump. It is just that it gives it when you are cranking only (in essence, it is a long story).

The solenoid you may have on FIP helps in start, but the key starting aid is this CSD. The usual issue is how it is activated - through several devices that usually do not work so well after 50 years. Some people do the short wire to CSD with a switch under dash.

Use the search "cold start issue" or "warm start problem" - you will read a lot.

And best - buy Membership for next to no money and you will have starting aids described in detail. Best investment I ever made.

[Tom in seattle]

I had an intermittent starting and running issue which turned out to be a badly fouled fuel filter which was interrupting fuel delivery, but not always.  Also, you can wire a switched wire from the ignition to the solenoid activated device on the intake manifold.  Push the button to energize the solenoid to manually inject extra fuel for cold starts. Maybe you have done  this already.