Author Topic: split linkage test results --what does this mean??  (Read 1455 times)

jonp821

  • Full Member
  • Junior Level
  • *
  • USA, CA, Upland
  • Posts: 15
split linkage test results --what does this mean??
« on: May 10, 2022, 21:56:16 »
Hi All---  so my '69 sl started missing and running rich after sitting a few months. Particularly missing just off Idle and smoking quite a bit. During my diagnostics I did a split linkage test and got some interesting results that I'm not sure what to do with.

With the Fuel pump linkage disconnected and opening the air portion of the throttle, the engine accelerates just as if the pump was connected.  When I move the pump linkage it makes no difference what so ever in the engine speed.

I checked the Injection pump rack by inserting a screw in the inspection hole in the front, and it moves freely back and forth. 

Is this symptomatic of a stuck WRD or do I need to look elsewhere.

Many thanks in advance!!
jonp
'59 190D Binz wagon
'69 280 SL
'51 220

roymil

  • Full Member
  • Senior
  • ***
  • USA, TX, Austin
  • Posts: 143
Re: split linkage test results --what does this mean??
« Reply #1 on: May 11, 2022, 02:23:36 »
Hello,   You didn't mention the temperature of the engine or the amount of the RPM increase when you did the linkage test.  Assuming it was fully warm, adding only air to significantly increase RPM certainly confirms its rich but could also point to a leaky cold start valve, dripping raw fuel into the intake.  The CSV seems a more likely suspect after sitting a few months but the WRD is easy enough to test with directions found several places on this site. 
Mark Miller
1968 280SL
Rode in his pagoda's first mile.

kampala

  • Full Member
  • Platinum
  • ******
  • USA, CA, Hermosa Beach
  • Posts: 1205
Re: split linkage test results --what does this mean??
« Reply #2 on: May 11, 2022, 03:44:34 »
Read this - same symptoms - with simple solution.   Worth checking:


https://www.sl113.org/forums/index.php?topic=31398.msg227770#msg227770
250sl - later - manual
280sl - 1971 - Auto - LSD

Aslam

jonp821

  • Full Member
  • Junior Level
  • *
  • USA, CA, Upland
  • Posts: 15
Re: split linkage test results --what does this mean??
« Reply #3 on: May 11, 2022, 14:09:24 »
Thanks Kampala ----- those are my exact symptoms.

I checked the BC and it is tight. How ever I decided to take it off, check it over and compare it to the one in the Tech manual. The measurement is exactly 21mm from the nut to the top of the pin-- so that  should be fine.  It has only one thin shim installed.  From what the Manual says, if anything, these fail on the lean side so I guess I can rule that out.

The pump is dumping so much fuel at idle the exhaust is wet and splattering on the driveway.

 I can drive the car with the pump side of the linkage disconnected and it accelerates thru shifting at 4000 RPM almost like normal.  The pump appears to be stuck in full acceleration mode.

Are there any of the devices or adjustments on the pump that might account for this???

The rack on the pump is moveable with a 10 mm screw per the tech manual and springs back into place. Does anybody know how far that rack should normally move??

Is it possible the linkage arm and control shaft on the side of the pump could become disassembled from the interior workings of the pump during acceleration and the pump got stuck there?

I am so stumped on this!!!
jonp
'59 190D Binz wagon
'69 280 SL
'51 220

kampala

  • Full Member
  • Platinum
  • ******
  • USA, CA, Hermosa Beach
  • Posts: 1205
Re: split linkage test results --what does this mean??
« Reply #4 on: May 11, 2022, 15:33:43 »
CSV?   The valve connected to the air intake manifold on the right side of engine.  I disconnected the fuel line and blocked it to confirm it was not sending fuel.  You can also open the 6 or 7mm screw on the side near the csv and see if you find fuel leaking in.

I know nothing about fuel injection pump itself so can’t help there.
250sl - later - manual
280sl - 1971 - Auto - LSD

Aslam

jonp821

  • Full Member
  • Junior Level
  • *
  • USA, CA, Upland
  • Posts: 15
Re: split linkage test results --what does this mean??
« Reply #5 on: May 11, 2022, 16:18:56 »
Hi --- The CSV was one of the first things I checked as it turns up so often on the forum. 

Thanks for your help on the BC, it sure sounded like a possibility.
jonp
'59 190D Binz wagon
'69 280 SL
'51 220

Cees Klumper

  • Platinum
  • ******
  • USA, CA, De Luz and Los Angeles
  • Posts: 5502
    • http://SL113.org
Re: split linkage test results --what does this mean??
« Reply #6 on: May 11, 2022, 20:57:37 »
Some of the little pistons inside the FI pump stuck inside their bores? 
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II

ja17

  • Full Member
  • Platinum
  • ******
  • USA, OH, Blacklick
  • Posts: 7308
Re: split linkage test results --what does this mean??
« Reply #7 on: May 12, 2022, 15:50:27 »
Check to make sure the WRD is not stuck in cold engine position. It's not likely the pistons in the pump are stuck if the rack is free.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

jonp821

  • Full Member
  • Junior Level
  • *
  • USA, CA, Upland
  • Posts: 15
Re: split linkage test results --what does this mean??
« Reply #8 on: May 16, 2022, 16:17:48 »
Greetings All --- Thanks for all the input --- cleaned, lubed and replaced the bulb in the WRD, ---All is well !!! Again many thanks for all the input----jon p
jonp
'59 190D Binz wagon
'69 280 SL
'51 220