250SL how do I adjust the hot idle?

[Arthur Dalton]

If the rack has to be used to add that much fuel to keep it running, you have a fuel problem.

It may be crap from sitting that long , it may be the screen in tank , etc..
Pump may be full of crap ... one of my early post said to pull the coil pos and then turn the key ON to let the electric pump run for a while..the reason for that was to get some new gas circulating thru the system and pump to help clean out the gum/gunk.....does not always work, but can't hurt.
The point is, you do not want that sol to have power to it except for when the starter is energized..if that rack is foward all the time , we can make adjustments til the cows come home in vain. Had I known you had that hooked to 12v all that time, I would not have had you doing some of the standard test I use.

But . don't worry..it will get fixed There are several things wrong and each one has to be addressed to get to a final correct running .
I am trying to do a step by step , but there is a lot wrong compared to your normal " won't idle well " complaint..and most is due to the long sit and PO screw-ups.

You have correct throttle plate adjustment now, along with vac at the port for retard, and oil level in pump correct and changed, so you are making progress...The ign timing should be looked at next just so you do not waste a lot of time with adjustments , only to have to go back after the timing is set .
That will be easy...I would start by marking the balancer at TDC,10 BTDC , ans 30 BTDC, Then I would get the engine RPMs to 3 K and turn the dist til you get 30 BTDC @ 3K with strobe. That is Ball Park for that distributor.
we can work from there ........
If you can not get it to stay running , rather than 12v to rack sol, you can take the ball link off the pump lever and push down by hand on the pump to see if that will get you enough to keep it running..can go back later to readjust those links.

One of the main problems you have and is concern is that pump knob ajduster screw in the pump..hope someone did not screw up the head on that ...try it as I posted before anything else. You want to know if you can feel a distinct slot [ like a flathead screw would have]..as you turn and push in on the knob at the same time , you will feel it when the adjuster drops into the screw slot of the adjuster...when that happens , you know you are in the slot and you have to hold that knob IN and try to turn that adjuster CCW , just like you were using a screwdriver with a Blindfold On ...

[Jerry Cohen]

I don't want to hijack the thread, but I can't help remembering a hack mechanic pushing the adjuster knob on the back of the pump while the engine was runing. It got ugly fast, the knob somehow locked on and spun at speed.

The car? It was only a RHD W112 300SE cabrio, why would you let a gas station mechanic even open the hood on a car like that?

Hijack over.

Btw, I've been following this thread with great interest. As I will probably have to awaken my W128 sedan this summer. It's been sitting since 1995, when it ran out of gas in the garage. Funny how life gets in the way.

[Arthur Dalton]

Yeah... I have been doing these for years , so you can just imagine how many I have seen.
That is why I use caps when I write 'NEVER TURN KNOB " with engine running..they think they are working on a Carb ..

"Hey, I was jus givin' it a little tweak, Man... "

Cool...why didn't ya just use a hammer ???

[mespe]

OK my cigar lighter is now a cigar lighter once again. The wiring to the solenoid on the IP is back to the way it originally was. The car starts up and runs, no black smoke at idle, puffs of black smoke between gears when driving. Hot idle adjusted to 950 RPM, idles pretty smoothly.

I think I'm going to remove the solenoid on the IP to have better access to the fuel enriching knob. Gonna try to get it to turn CCW.

I'm assuming that the puffs of black smoke might go away if I can get the fuel enrichment knob turned.

The problem with ignition timing at the moment is that my timing light doesn't pick up the spark voltage reliably. I have new points I can put in, but,,,

Currently the plugs are bosch plat's simply because the copper NGK's fouled up and wouldn't spark. Do you recommend the copper or the platinum plugs?

I felt good after the progress yesterday, after this morning I feel great.

As far as the rack solenoid is concerned, before I did the things that Arthur Dalton recommended, when I cut power to the rack solenoid, the car would stall! Now she's hooked up back the way she should be and runs 1000% better.

[Arthur Dalton]

>


Dump the plats...that car should run great with NGK coppers ..better than Bosch on MFI cars.

What NGK # did you have in there ??
PB5EFS ??

And now that it is running, do that vac retard test again.
I want to know the rpms @ idle when you remove that TP vac line..that will tell me a lot about your ditributor and timing. Car up to temp.

I don't want to sound like a broken record, but I must stress the importance the ign timing has on ALL the adjustments of the MFI system.

Us MFI guys won't even turn a screw on an MFI car until we set the ignition to spec b/c we know what a diference both that and the likage adjustments make on these. It is a MUST DO.

And when up to temp, one more easy test.
Take the ball socket off the cross shaft on the pump side . Then . at idle, push the pump lever down slowly..does the rpms increse or decrease?

[Arthur Dalton]

There was another post here a few weeks ago that had the same problem with someone running the knob in with car running and it locked up the screw...
If you want to read that one, it might help you out as to how he did it.
If all fails , you have to take the big nut off the back of the pmp to get to those inner parts.

If you can;t find it, I will........

If you can get the knob to seat well into the slot and it feels secure , you can often use a pair of plyers/grips to aid in turnng the knob to free it..but use finesse. If the driver does not sit well in the screw slot, [ pops out] , then you have a stripped screw adjuster head or driver and the things has to be removed.
If you do get it free , you will know b/c you will then feel the clicks I mentioned earlier...then we can set the a/f mix and idle correctly

[mespe]

The IP's fuel enrichment knob will not tjurn for love, or money,,, or brute force. Looks like I'll remove it to fix. If it is currently turned all the way CW, how many clicks should I go CCW to get close to where it should be?

NGK's are BP6ES

I think I should get this tackled before I do anymore adjustments/ tests

[Arthur Dalton]

[QUOTE=mespe;2206562]The IP's fuel enrichment knob will not tjurn for love, or money,,, or brute force. Looks like I'll remove it to fix. If it is currently turned all the way CW, how many clicks should I go CCW to get close to where it should be?

About 6 , for starters

NGK's are BP6ES

Those are good for 129 engine

I think I should get this tackled before I do anymore adjustments/ tests

That and the TIMING..you do not want to be making that adjutment BEFORE correct timing .. or you will have to do it again AFTER timing.
The adjustments will not effect the timng, but the timing wil leffect the adjustments ..see?????
Borrow a light somewhere ..you are going about this backass.
We are almost there ..correct timing, a few tweaks and test, and you will then re-read this whole scenario and see what the logic was , right from the get-go.
Did you try grips on the Knob??

[Arthur Dalton]

Here is a pic of the adjuster screw in the pump that you are trying to turn with the knob..[JA17 pic]

Just so you know what you can not see.

http://www.sl113.org/forums/uploaded/ja17/2004615233724_gov.%20low%20range%20adjuster%20screw.JPG

..and here it is assembled..it is the big center one..the other small ones are the range screws DO NOT TOUCH THEM..........Please.

You can see the little spring clips on eachside of the screw Hex Head,, those are the locks and that is what makes the CLICK..one click for each hex head flat.

http://www.sl113.org/forums/uploaded/ja17/2004615233440_rear%20pump%20cover%20off.JPG

[mespe]

Took the cover off the fuel enrichment knob. The fuel enrich bolt circled in the picture turns freely both directions.

Is the footbal shaped plastic piece the part that should turn with the clicks?

[Arthur Dalton]

OK

That is it.

we will use JA pic b/c I can not make yours out.

You see the center adjuster ..it's head is a HEX...the 'Football " is not a football..it is a spring clip..and you will see that when you turn the HEX screw, the spring clip allows you to turn the hex until it gets to the next lock on the hex.. [ 60 degrees of turn..1/6th turn b/c the hex has 6 sides] ...than it clicks to hold the hex from turning..it is a spring loaded hex lock..if you look real close , you will see that the clip touches ALL ADJUSTER screwheads Hex sides to lock them all, yet it is only one clip on each side...a very nice design, if I may say so , myself.....it's sole purpose is to hold your last adjustment , yet still allow turning of the screw in 1/6th incremental turns. And it locks all 5 screws so they can't change your last adjustment.

If theclip does not click/lock as you turn the screw , then it is broken or bent ,etc. They have a distinct Click at each setting and you can feel it in the knob..I can even hear them.
I noticed you referred to it as plastic football.. it should not be plastic. it is spring steel ..so, either you think it looks like plastic or someone has been in there with some more Gerry-Rig...take a close look at that clip.

let me know if you get that..

If it turns Ok, then I have no idea why you could not turn it w/knob...is the knob frozen or something???
...How is the screwdriver end of the knob...is it broken off ???

[mespe]

I now feel and hear a distict click while turning the knob. Although turning the knob does not seem to effect idle speed. max at temp = 1200 RPM by adjusting the AB

I don't know either why it was stuck, but it's moving now and I turned it CCW about 8 turns still high idle,,, keep turning?

I also noticed back firing stopped when revved up, and a more gradual return to idle speed.

distributor vacuum interrupt test

AB adjusted for 950-1000 RPM idle increased to 1250 RPM
AB adjusted for max RPM, (1240 RPM) idle increase to +1600 RPM

[Arthur Dalton]

Very Good// Do you have someone there helping you?

Ok ..the rpms @ idle w/warm engine are still high.
Do you still have air entering the WRD ?

IF NO , then turn the knob CCW a couple more clicks and then retrim the AB...keep doing that until you are down to approx 950RPM..and smooth.

On the retard test..PASS. So that parts is now fixed.

Still need te TIMING b/c that effects the idle speed .

[mespe]

I believe I hear air entering the WRD after the car warms up to temp.

No one here right now, but I can get someone here.

Still trying to round up a timing light, but I gotta ship some parts out before I can start work on the 250SL again.

[Arthur Dalton]

OK
We are now down to no furhter adjustments until you do the timing...so get a light...buy one if you have too. You just need the cheapo kind.

Any rpms now can be the product of advanced timing, so we need that done.. You want TDC w/vac @ idle/900rpm and 30BTDC at 3K for base line timing..then we can tweak and address the remaining problems.