1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

1991 Sambar loses power and dies after 10 minutes

Discussion in 'Subaru Sambar' started by Everest_man2001, Feb 15, 2021.

  1. Everest_man2001

    Everest_man2001 New Member

    My 1991 KS4 Sambar starts and runs okay for about 10 minutes. It seems to starve for fuel once the engine warms up. This has been a problem for the last couple of years but has gotten worse to the point I have to wait for the engine to completely cool down before it will start. These are the things I have done so far to try to remedy the situation:
    1, Checked fuel pump and filter. 3.1 PSI at carburetor (the pressure and flow are still okay when the engine dies).
    2. Checked carburetor solenoids. Removed both and tested, both worked when 12VDC was applied to them.
    3. The only way I could get the vehicle to start recently is to constantly power on the fuel shutoff solenoid on the lower drivers side of the carburetor.
    4. Checked and cleaned the plugs.

    Does anyone know how the 2 solenoids on the carburetor are powered? I have the repair manual but the wiring diagrams do not show the 2 solenoids (if they do, I can't find them).

    Any help will be greatly appreciated.
     
  2. Limestone

    Limestone Well-Known Member

    Everest,
    As long as they tested good, like you said, they sound like their working properly. However, they are part of the fuel system, as you know, and even the tiniest particles of dirt and gunk can interfere with their performance! Has the vehicle sat for any length of time? I see that you said you checked the Filter! How did you check it? By visually inspecting flow? I understand, that, and I am pretty picky about changing fuel filters! That being said, the one solenoid on my Daihatsu, sends fuel to the carb. upon, start, and the other, is an Anti dieseling solenoid, if you will, that stops post Ignition! I found this out first hand testing, and verifying, first hand! I have a single wire, and a double wire solenoid on my original carb. Note:( I no longer am using the original carb., because I have a case leak on the 2 wire solenoid, and can't find a replacement)! You say that the only way to get it to start is to power up the one solenoid constantly, giving it power! Will it stay running, doing this? Not sure if you can even find a replacement solenoid, for yours, as none seem to be available for my original carb. The aftermarket carbs. use a manual choke, eliminating a solenoid, for the Daihatsu! Crazy! These Carbs. seem to be a problem for a lot of Folks! Maybe someone can chime in with a Sambar, and help, with more Technical help!
    Limestone
     
  3. Patrick Nguyen

    Patrick Nguyen New Member

    Are you certain it is not overheating? What is the hot air coming out of the blower fan like?
     
  4. Everest_man2001

    Everest_man2001 New Member

    Patrick, I'm sure it is not overheating, it barely gets to operating temperature when it shuts off. Thanks
     
  5. widmerhd

    widmerhd Member

    Just a thought, but if it stays running when you provide constant power to the solenoid, it may have been an intermittent power supply problem to the solenoid that is now a permanent problem. I would check the power supply to the solenoid. ( had a similar problem with a coil pack once, when it heated up, expansion created electrical problems) So maybe there is a hot spot in the electrical supply line?
     
    Last edited: Feb 19, 2021
  6. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    The 3.1 sounds high. My Hijet is set down to 2.5, which from what I’ve read is about right for these carbs. On the standard Hijet carb, one solenoid is the idle cut, and kills fuel to the idle circuit when the key is off, to prevent Dieseling when you shut off the engine, and the other is the vent for the fuel bowl and to allow vapors to go to the charcoal canister.

    Some of he LHD import Hijets had asolenoid, which when you hit 25-mph would pulse in and out of the main jet, to prevent you going any faster. Somehow, I can’t see that not burning the valves and valve seats.
     
  7. Everest_man2001

    Everest_man2001 New Member

    Widmerhd, It will only start with the fuel shutoff solenoid powered. Even with it constantly powered it still shuts off after about 10 minutes of driving. I don't think that is the problem. What ever the problem, it is related to when the engine warms up. Thanks
     
  8. Everest_man2001

    Everest_man2001 New Member

    Jigs-n-fixtures,
    If I am understanding you correctly, the idle circuit solenoid should only be powered when the engine is running? What about the vent solenoid, does it vent anytime the engine is running or just when the engine warms up? I can't seem to find the wiring diagram for either of these solenoids in the service manual. Thanks
     
  9. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    The vent solenoid varies by manufacturer and year. Some engine/carb setups the solenoid does two things, vents the fuel bowl to the charcoal canister, and then when the engine is running, closes the vent to the fuel bowl, and connects the line to the canister to a passage in the carb which applies manifold vacuum to the canister to pull the capture vapors back out of the canister and into the engine to be burned.

    I would install a pressure regulator, and bring the fuel presssure down to the 2.5 range. If you can get a rebuild kit for the carb, I recommend replacing the needle and seat.

    On My Hijet, the mechanical fuel pump had a relief valve in the fuel pump to regulate the fuel pressure, and would return excess fuel back to the fuel tank. The Charcoal Canister was clogged, so the return line was pressurizing the fuel tank, and that was causing enough excess pressure in the fuel system to push fuel past the needle and seat in the carb. Which caused the truck to run rich all the time.

    My roommate back in the eighties, had a Toyota Celica which would run for about ten minutes and then would loose power and stall out. We finally tracked that down to something fibrous in the fuel tank, which was just dense enough that when the ar wasn’t moving it would settle to the bottom of the tank, and when it started moving and agitating the fuel a bit, would float up and pack around the sock filter on the fuel pickup. That restricted the flow and the car couldn’t get fuel to engine, and would die out.

    Other things which might cause it to stall out after running would be coming from the electrical side of things.

    My Brother had a Dodge pickup, which would run ok for about thirty minutes and then would miss and stall out. I tracked that down to a bad coil. As the truck ran, the coil would warm up and then start shorting internally. I tested the resistance when the coil was cold, and it was within the range in the Haynes manual. But checking it again after the truck started having problems it didn’t have enough resistance to the tower.

    G&R imports has a good page on trouble shooting “carb” problems. Almost all of the trouble shooting is electrical in nature. I highly recommend that you go to their page and do the run through before futzing with the carb. If you pull a plug and it is wet, it means one of two things: Your running rich; or, you don’t have enough spark and the fuel isn’t burning completely. 90% of the time folks assume it is the carb. While in reality, 90% of the time it is ignition related.
     
    Diesel_Gypsy and Limestone like this.
  10. WarWagon91

    WarWagon91 New Member

    Did you solve your issue? I had a similar problem with my 91 KS4,turned out to be a slightly untuned carb. Now she purrs like a kitten.
     

Share This Page