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95 Sambar - How to test choke pull-off?

Discussion in 'Subaru Sambar' started by keimasterflex, Sep 25, 2023.

  1. keimasterflex

    keimasterflex New Member

    All of the text below is context if you have better ideas (cause I know very little about carbureted engines) but my main question right now is -- when testing a choke pull-off for a 95 Sambar KS4, when I apply a static vacuum should it hold position of the plunger indefinitely, or do we expect it to slowly leak some air and reset to default after a few seconds?

    I have a 95 Sambar V-KS4 EN07 that runs absolutely perfectly the moment it's hot. Once the temp needle moves up high enough to be on the gauge, like flipping a switch it's running great and doesn't bog when I ask for power.

    But when the engine is cold and I start it, it will start and runs rough. I can visibly see more shake in the engine and if I try and rev it it sometimes kills itself on it's way back down. The truck can't really go anywhere until it's fully hot.

    I am not familiar with carbureted engines so I did some research, asked questions, and did some testing. Like many of you probably already realized at this point, it seems choke related. I confirmed this by starting the engine cold and while it was running I can pull on the choke pull-off linkage, opening up the choke and I can get it to run great while still cold.

    I confirmed that the choke pull-off does get vacuum signal when it's running cold (by pulling off the hose, I can hear wooshing and it will suck my finger to the end), and I can see the linkage at least move, though apparently it's not enough?

    At this point, not wanting to mess with any adjustments and cause any issues with my truck that I can still drive, I bought a used carb from Japan so I can look at and learn without messing with mine, plus it had a choke pull-off on it so maybe I'd get lucky and this used one would be good and mine would be bad.

    I tested both choke pull-offs and when I apply vacuum to either of them I can get the linkage to move fine, but the plungers slowly leak air, they don't hold their position. In my googling about choke pull-offs I can find stuff about primary vs secondary pull offs and that some should hold air and some have a bleeder hole.
     
    Last edited: Sep 25, 2023
  2. 97Sambar-TCF

    97Sambar-TCF New Member

    Both (the one on the truck and the one on a “rebuilt” carb I have) of mine also leak down. I removed the valve thing that’s in the vacuum line and it runs better when cold now.

    Update: I did have to put the delay valve back in the choke vacuum line to get it to start when cold. I was able to determine that the previous owner had it in backwards. It seems to run better during warmup with it reversed.
     
    Last edited: Apr 14, 2024
  3. This may be a silly question, but is the carb clean?
     

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