230SL Fuel Injection Pump Cold Start Solenoid Adjustment

[mistertj]

My 1964 230SL fuel injection pump has a cold start solenoid mounted of the rear of in. If you take the solenoid off, there is a threaded rod in the center that looks like it can be adjusted. Does anyone know what the adjusted length should be? The reason why I ask is that I recently removed the pump and in dismantling it, removed the solenoid. It was spring loaded to about a 1/4" and popped off. That means that unenergized, the solenoid shaft was pushing on the linkage inside the pump. That does not seem correct...so I am asking. Oh incidentally, I am still having a problem getting the engine to run below 2,000 rpm. So have sent it off to have a professional rebuilder look at it. Thinking that this spring loaded solenoid might be a contributor.

[wwheeler]

There is a spring loaded lever that the solenoid rod sets against. That is normal. Once that lever is depressed, it acts on the rack. I do believe it is possible for an un-energized solenoid to push on the main rack if the rod is adjusted all the way out. The best way to tell is to remove the rubber plug on the front of the pump. You can then access the main rack and the threaded end. Put a screw (not sure what size) in the rack to use as a position gauge. By monitoring the rack position when the solenoid is installed and removed, you should be able to determine if when un-energized, it is acting on the rack. If the rack moves out when the solenoid is installed, then the rod is adjusted way too far out. This solenoid acts directly on the rack and is not effected by the governor.

But as far as dimensions, that's difficult. Sending it off for professional adjustment is probably better.   

[mistertj]

Thank you. I know the screw/bolt you are talking about.

[mrfatboy]

That solenoid is only energized when the starter is engaged.  It moves the Rack forward providing a slightly richer mixture for starting only.

If you say that solenoid is adjusted in such a way that it is pushing the Rack forward all the time with out it being energized that would explain the extra fuel and hence the high idle rpms.

If you have not sent the pump out yet I would adjust the solenoid pin all the way in so that it does not push on the Rack energized or not for a test.  You will have to adjust your air screw to compensate. I would think your rpms would come down then.

I know some people disconnect this solenoid and don't even bother because they have rich starting conditions.  My solenoid is connected but is adjusted all the way in as to not push the Rack forward during starting.  The result is the same.  However I don't have an unconnected wire dangling.

[A Dalton]

  et al ,

 Post 23

 https://www.sl113.org/forums/index.php?topic=23978.msg175168#msg175168

[mrfatboy]

Very good point and extra added insurance. I didn't know the pins could snap off.  My fip already has the newer ball valves. 

[A Dalton]

 I have seen a few  where the broken shaft punched a hole right thru the case.

These pumps are getting old and brittle.

A stub shaft was a poor design , right from the get-go.

A solenoid is not a smooth acting device..they snap pretty  hard and do break the lever support pin after many years/miles of constant banging.
Not needed w/ball valves, so a disconnect is advised...or mod the shaft before it breaks.

[wwheeler]

Question: I have a later (and I think R28 or maybe R20 pump) for my '68 280SE. Does this have the same weak support issue? I do have the start solenoid BTW. You had mentioned in the early post for pumps up to and including R18.

BTW, I now have two switches in the cabin, a "live" momentary button for the CSV and an on/off for the starting solenoid. The CSV still uses the relay/TTS system. This is just in addition to that. I am in the process of documenting  when to activate which and under what condition. So far, works well. My three variables are: 1) ambient temperature 2) engine temperature and 3) how long the engine has been shut off. I never have to worry about flooding the engine and can apply as much fuel as I need to get it to start quickly under any condition.   

[A Dalton]

 Any pump with the rack start sol uses the stub shaft...which is why I rec unplugging the sol feed.
The main reason for the sol is the cone valves did not hold  injector line pressure well, where the ball valves  did..specially the later  modified 4mm ones.
So, if pressures were sustained , the rack did not have to be electrically  slammed open.
Thus, it was eliminated  w/balls.........
It is this rapid movement/force that breaks the poorly supported shaft.
So, even if one controls  the sol by a manual  cabin switch, the shaft can still break.
 They usually snap right off flush with the case.
I have explained the machining remedy...but power feed disconnect assures no  further shaft strain.
 I have also caught a few before case damage by actually hearing pump rattle @ idle, where the pin was broken, but had not yet jammed into any moving parts ..thus saving the day.
 Not a common failure , but have seen enough to post this FYI

 

 

[mrfatboy]

@A Dalton

You made me a believer.  I just disconnected mine. No need to push my luck especially when the solenoid was not doing anything in the first place

What about the lower fuel cut off solenoid?  Wouldnt that have the same type of failure?

[wwheeler]

Another thought about the starting solenoid. It does more than slightly enrichen the mixture. When activated, it pushes directly on the rack to "Full rich" position. There is a diagram somewhere that shows the position and the full rich is as far as the rack goes. BTW, opening the throttle on the pump is NOT the same position as the full rich. Reason being is that the throttle works through the governor and not directly on the rack like the solenoid.   

[A Dalton]

 Yes ...full rich w/sol activated.
The reason being they want as much fuel available to reach the injectors as fast as possible w/o any pedal..meaning no air from throttle.

 So, the pump rack at full fuel  is compensating for the  leakdown of the lines due to cone valve leakage, along with any injector leaks.

..and all cones leaked.

Another reason why I recommend cabin switch wired direct from bat/run  feed so that one can squirt fuel into the plenum BEFORE starter crank .  Simply turn key to run for fuel pump pressure to CSV and hit the cabin sw for a sec or 2 for CSV squirt.
This allows for faster starts even with bad cone valves. It will instantly start from the plenum vapors, and once running, the pump fills the leaked down lines
A primer, if you'd like.............

[wwheeler]

The only time I switch on the start solenoid is when the engine is below 100*F and has not been run in 6 hours or more. In the summer time in Texas, it can take the engine a few hours to cool down below 100*F. I do activate the CSV with only the pump on (engine off) and maybe I can experiment using more of that and no starting solenoid. Who knows, maybe I can stop using start solenoid altogether. I'll give it a shot (pun intended) this weekend.

Question on the ball valves. You mention there was an improved ball valve and how would you know if you had those? My pump has been rebuilt by Pacific FI and not sure if he automatically uses the best ball valves or just reuses what is there. My pump is a R20Y.

Thanks.

[Shvegel]

According to this the 22y was the first pump without starting solenoid and with the ball delivery valves.  Look at the USA specs.
https://www.sl113.org/wiki/Fuel/Injection

[A Dalton]

 Ball valves introduced  with R18z pumps on 250sl.
Which is a Euro pump.

 The start sol was eliminated when the ball valves were modified to 4mm.

Meaning  you can have an early ball valve pump w/sol.

 Many differences between US and Euro version b/c US was getting into Emissions Mandates at that time. Specially late .044 chassis.

Which is another reason many of us prefer Euro cars....

I will try and post my Euro spec carts.

I see pumps that don't jive with the charts, but they may have been changed at some point
I also over the years have seen spec charts that don't jive  with one another ,  so,,,,,,,,,,,,,,,,,

B/C these are analog systems and see mechanical wear, no two start the same...and we all get to know what our cars likes.
Knowing modern  EFI, I am amaze these MFI systems do as well as they do.

I compare them to an old mechanical typewriter....but we do love them to death b/c of MFI, faults and all,  They tried many versions and get an A for effort, but they  never did get it perfect...but again, how could they with the tech of the time. Even the TTS is a mechanical sensor...and mechanical points went out with horseshoes.
So, we try different mods , like it or not , to get our little 113 to run just a little bit better...frowned upon by the purist, enjoyed by the tinkerers...and in many cases,  a much better running car.
Consider the  performance differences made with the simple addition of the higher torque starter, electronic ign [ of any type], CSV controlled from cabin switch [ prob the best  $$$ value mod on any MFI car], etc, etc..  the list is long.
...and then again, a 113 in  maintained mechanical order runs just as well as can be ..plus they look great too, don't they ?  !!

[wwheeler]

So can you retro a pump with the early ball valve to use the later 4mm ball valves? Is the difference just the size of the ball?

Thanks.

[rgafitanu@gmail.com]

Anybody knows what is the function of relay 20 (used in the CSV and the IP solenoid circuit) in the two color 230SL schematics from the technical manual? They appear to be holding to ground the other relay's coil while the starter is NOT energized. Anybody knows why?

[glenn]

According to this the 22y was the first pump without starting solenoid and with the ball delivery valves.  Look at the USA specs.
https://www.sl113.org/wiki/Fuel/Injection

Ball valves introduced  with R18z pumps on 250sl.
Which is a Euro pump.

 The start sol was eliminated when the ball valves were modified to 4mm.

Meaning  you can have an early ball valve pump w/sol.

 Many differences between US and Euro version b/c US was getting into Emissions Mandates at that time. Specially late .044 chassis.

Which is another reason many of us prefer Euro cars....

I will try and post my Euro spec carts.

I see pumps that don't jive with the charts, but they may have been changed at some point
I also over the years have seen spec charts that don't jive  with one another ,  so,,,,,,,,,,,,,,,,,

B/C these are analog systems and see mechanical wear, no two start the same...and we all get to know what our cars likes.
Knowing modern  EFI, I am amaze these MFI systems do as well as they do.

I compare them to an old mechanical typewriter....but we do love them to death b/c of MFI, faults and all,  They tried many versions and get an A for effort, but they  never did get it perfect...but again, how could they with the tech of the time. Even the TTS is a mechanical sensor...and mechanical points went out with horseshoes.
So, we try different mods , like it or not , to get our little 113 to run just a little bit better...frowned upon by the purist, enjoyed by the tinkerers...and in many cases,  a much better running car.
Consider the  performance differences made with the simple addition of the higher torque starter, electronic ign [ of any type], CSV controlled from cabin switch [ prob the best  $$$ value mod on any MFI car], etc, etc..  the list is long.
...and then again, a 113 in  maintained mechanical order runs just as well as can be ..plus they look great too, don't they ?  !!

You got it right..  No two were built the same, but they were pretty good for analog....

[66andBlue]

....
Which is another reason many of us prefer Euro cars....
I will try and post my Euro spec carts.

Hi,
we are waiting for the charts! 

[rgafitanu@gmail.com]

Thank you A Dalton for the CSV activation BEFORE cranking idea. I wired a momentary switch to the relay so I can give a 2-3 seconds squirt right before cranking. The car starts immediately now. It used to be a hit or miss even with the switch that was grounding the CSV regardless of the engine temperature (bypassing the thermo switch). Next I will try with the enrichment solenoid off.

[A Dalton]

 You're Welcome.

[ja17]

Another mod. for the non-purist....If you have an enrichment solenoid on your IP and a later starter with an ignition bi-pass, you can modify and simplify your automatic starting system even further. Delete the electrical relay which activates  the enrichment device on the IP. Connect the enrichment solenoid directly to the by-pass terminal on the newer style starter (activates whenever the starter is engaged).  The result is that the enrichment device on the IP functions as designed, but is activated by a simpler and more robust circuit.

[ja17]

Hello Radu,

With Starting Aids Version II (earliest W113s) relay #20 is a one second time relay. It provides ground (earth) to relay #21 (enrichment solenoid relay) for one second when the starter is engaged. As with version II the relay 21 is also supplied ground (earth) through the TTS which gives only the IP enrichment solenoid  an engine temperature and time duration function. An additional temperature sensor was used on this model (thermo switch) which differed from the thermo time switch. The "thermo switch" is simply an engine temperature on-off switch, with no time duration function. This thermo switch controlled ground (earth) to the relay #19 which activates the intake starting valve below a certain engine temperature.

With Starting Aids Version III, the relay #20 is a time relay and is activated for one second only. This relay #20 controls the ground (earth) to relay #21 which activates the both the enrichment solenoid and the intake starting valve for one second,  on this version when the starter is engaged. However relay #21 is also supplied ground (earth) through the TTS (thermo time switch). In this way, with this version, both starting devices also have a temperature and duration period for both starting devices. (See the chart for version III in the tech manual).


With Starting Aids Version IV, relay #20  activates the intake starting valve  by supplying it with the positive power whenever the starter is engaged. The ground (earth) is supplied to this #20 relay through the TTS, which enables it to function at the designed engine temperatures and durations.

With Starting Aids Version V, relay for the enrichment solenoid is deleted and not installed at the factory.

[wwheeler]

Radu,

Is your CSV completely controlled by the cabin switch? Or does it still have the Automatic function and you supplement as needed?

Thanks,

Wallace

[rgafitanu@gmail.com]

The CSV still operates as designed. I only wired a momentary switch in parallel with terminals 87 and 30/51 (relay contacts). With ignition on I give it 4-5 seconds on the switch and I release as I turn the starter on. The engine fires immediately exactly as described by A Dalton.