split linkage test results --what does this mean??

[jonp821]

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!!

[roymil]

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. 

[kampala]

Read this - same symptoms - with simple solution.   Worth checking:


https://www.sl113.org/forums/index.php?topic=31398.msg227770#msg227770

[jonp821]

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!!!

[kampala]

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.

[jonp821]

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.

[Cees Klumper]

Some of the little pistons inside the FI pump stuck inside their bores? 

[ja17]

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.

[jonp821]

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