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  1. #1

    Default carb issue on 2000 90hp johnson

    With engine idling I pulled off one spark plug wire at a time and the lower starboard cylinder was the only one that didn't show a difference.
    Swapped the plugs and wires and had the same results.
    Swapped the lower carburetor assembly with the upper. The problem moved to the upper, followed to carb. Completely rebuilt all 4 carbs (new floats, needle valves, gaskets, etc...).

    Sill have the same problem......Any ideas????


    Also seem to have a fuel flow problem, separate issue ??
    Out on the water under a load the engine bogs down. When I squeeze the bulb multiple times the engine takes off. I replaced all the gaskets on the fuel pump, made no difference. No sign of gas leaks when priming bulb.... Any ideas????

    Thank you in advance.

    Vin

  2. #2
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    Default Re: carb issue on 2000 90hp johnson

    Go back through the bad carb again. something missed.

  3. #3
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    Default Re: carb issue on 2000 90hp johnson

    Yep... The problem followed the carburetor... You're overlooking something within the carburetor. Check the fuel supply route to the slow speed passageway (very small brass tube).
    We occasionally have questions. If you fail to answer, it may affect ours.

  4. #4

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by Boobie View Post
    Go back through the bad carb again. something missed.
    Thank you.
    I agree and thought the same thing. I'll go through it again (4th time).

    Any thought on the fuel flow? Priming the bulb while under load makes the engine run better. Getting a new bulb today, replacing the cheap items first.

  5. #5

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by joereeves View Post
    Yep... The problem followed the carburetor... You're overlooking something within the carburetor. Check the fuel supply route to the slow speed passageway (very small brass tube).

    Thank you.
    Any thought on the fuel flow? Priming the bulb while under load makes the engine run better. Getting a new bulb today, replacing the cheap items first.

  6. #6
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    Default Re: carb issue on 2000 90hp johnson

    The primer bulb is nothing but a simple manual pump.------It is working since motor runs better when you operate it.-----Primer bulbs are there to save the starter motor from having to fill carburetors.----Or your arm / shoulder for manual start motors.

  7. #7

    Default Re: carb issue on 2000 90hp johnson

    But the primer bulb could be indicating a fuel pump problem, correct?
    Using the primer bulb is basically taking the place of the pump, correct?

  8. #8
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    Default Re: carb issue on 2000 90hp johnson

    Correct, in pumping the fuel primer bulb constantly and steady... whoever is doing the pumping is acting as a manual fuel pump.
    We occasionally have questions. If you fail to answer, it may affect ours.

  9. #9
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    Default Re: carb issue on 2000 90hp johnson

    So why did you state you were " getting a new one today " when it is working fine.----Concentrate on finding the issue with the pump on the motor.----Or the fule lines on the motor.----Or the float valves on the motor.

  10. #10
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    Default Re: carb issue on 2000 90hp johnson

    2000 model 90hp should have a VRO pump....which fuel pump did you replace gaskets in????
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  11. #11

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by racerone View Post
    So why did you state you were " getting a new one today " when it is working fine.----Concentrate on finding the issue with the pump on the motor.----Or the fule lines on the motor.----Or the float valves on the motor.
    Getting a new bulb in case the existing bulb has a leak causing air to get in.

  12. #12

    Default Re: carb issue on 2000 90hp johnson

    Replaced on the VRO pump. Fuel piston and O-rings.

  13. #13
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    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by Vin92 View Post
    Getting a new bulb in case the existing bulb has a leak causing air to get in.
    If a air leak exists... by the same token, fuel would be leaking out.
    We occasionally have questions. If you fail to answer, it may affect ours.

  14. #14
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    Default Re: carb issue on 2000 90hp johnson

    Do not lose track of your statement in post #1.... That the problem followed the carburetor when you switched them.

    The problem is with the carburetor.

    Should there be additional problems... let them go until the carburetor is functional.
    We occasionally have questions. If you fail to answer, it may affect ours.

  15. #15

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by joereeves View Post
    If a air leak exists... by the same token, fuel would be leaking out.
    Thank you!
    I appreciate the feedback.

  16. #16

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by joereeves View Post
    Do not lose track of your statement in post #1.... That the problem followed the carburetor when you switched them.

    The problem is with the carburetor.

    Should there be additional problems... let them go until the carburetor is functional.
    Thanks!!!
    Back to looking at the bad carb.

  17. #17

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by joereeves View Post
    Do not lose track of your statement in post #1.... That the problem followed the carburetor when you switched them.

    The problem is with the carburetor.

    Should there be additional problems... let them go until the carburetor is functional.

    Completely cleaned "bad carb" again. Same results (driving me nuts). New float and needle valve. Setup is the same as other3 carbs.
    There is not much to this carb assy #0439009. Switched to port side. Problem still followed carb again.
    If I can find a new carb assy, I will buy a new one. Seems crazy, this one looks good. Not sure what else to do or try.

  18. #18
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    Default Re: carb issue on 2000 90hp johnson

    Did you install the plastic washers under needle valve? Did you replace the cover plate gasket on idle/intermediate passages? Did you clean the passage tubes? Did you clean fuel passage as these bodies are fed from throttle plate?(my bet) Install the correct o-ring as there are 3 different ones?
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  19. #19

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by faztbullet View Post
    Did you install the plastic washers under needle valve? Did you replace the cover plate gasket on idle/intermediate passages? Did you clean the passage tubes? Did you clean fuel passage as these bodies are fed from throttle plate?(my bet) Install the correct o-ring as there are 3 different ones?
    New washer under needle valve - yes
    New cover plate gasket yes
    O-rings ??

    Float drop is 1" from the bowl gasket to bottom of float. Three other carbs are setup the same way.

    Thanks for your help/input.
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    Last edited by Vin92; 06-18-2019 at 08:25 AM. Reason: adding photos

  20. #20
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    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by Vin92 View Post
    With engine idling I pulled off one spark plug wire at a time and the lower starboard cylinder was the only one that didn't show a difference. Swapped the lower carburetor assembly with the upper. The problem moved to the upper, followed to carb. Completely rebuilt all 4 carbs.
    Vin... As per your original post (above) and your latest post #17, you have cleaned the offending carburetor (again)... and once again the problem has followed the carburetor. This proves a problem exists with the carburetor! A problem you are overlooking.
    ********************
    Yes, I know it's a PITA... BUT... yank that carburetor off again and pay particular attention to the very small off center brass tube that exists within the larger brass high speed nozzle.

    That small tube is the main fuel line supply to the idle fuel passageway at the top of the carburetor. If it is restricted in any manner (and I believe it is)... fuel is NOT able to travel to or thru the slow speed passageway, and the result would be exactly as you describe in post #1 and post #17.

    Solvent does not clean that passageway properly.

    Clean that small idle fuel tube carefully and thoroughly with a piece of single strand steel wire and compressed air... making absolutely sure that it is clean before reassembling it.

    Also make sure that the high speed jet, that lays horizontally in the bottom center of the float chamber, is absolutely clean as full must freely flow thru that jet before it can gain access to any other fuel passageway.
    ********************
    With no intention of insulting your intelligence, just a reminder to keep in mind............

    Einstein once stated that "The definition of insanity is doing the same thing over and over and expecting a different result."
    We occasionally have questions. If you fail to answer, it may affect ours.

  21. #21

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by joereeves View Post
    Vin... As per your original post (above) and your latest post #17, you have cleaned the offending carburetor (again)... and once again the problem has followed the carburetor. This proves a problem exists with the carburetor! A problem you are overlooking.
    ********************
    Yes, I know it's a PITA... BUT... yank that carburetor off again and pay particular attention to the very small off center brass tube that exists within the larger brass high speed nozzle.

    That small tube is the main fuel line supply to the idle fuel passageway at the top of the carburetor. If it is restricted in any manner (and I believe it is)... fuel is NOT able to travel to or thru the slow speed passageway, and the result would be exactly as you describe in post #1 and post #17.

    Solvent does not clean that passageway properly.

    Clean that small idle fuel tube carefully and thoroughly with a piece of single strand steel wire and compressed air... making absolutely sure that it is clean before reassembling it.

    Also make sure that the high speed jet, that lays horizontally in the bottom center of the float chamber, is absolutely clean as full must freely flow thru that jet before it can gain access to any other fuel passageway.
    ********************
    With no intention of insulting your intelligence, just a reminder to keep in mind............

    Einstein once stated that "The definition of insanity is doing the same thing over and over and expecting a different result."
    Thanks again - I appreciate your help!

  22. #22

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by joereeves View Post
    Vin... As per your original post (above) and your latest post #17, you have cleaned the offending carburetor (again)... and once again the problem has followed the carburetor. This proves a problem exists with the carburetor! A problem you are overlooking.
    ********************
    Yes, I know it's a PITA... BUT... yank that carburetor off again and pay particular attention to the very small off center brass tube that exists within the larger brass high speed nozzle.

    That small tube is the main fuel line supply to the idle fuel passageway at the top of the carburetor. If it is restricted in any manner (and I believe it is)... fuel is NOT able to travel to or thru the slow speed passageway, and the result would be exactly as you describe in post #1 and post #17.

    Solvent does not clean that passageway properly.

    Clean that small idle fuel tube carefully and thoroughly with a piece of single strand steel wire and compressed air... making absolutely sure that it is clean before reassembling it.

    Also make sure that the high speed jet, that lays horizontally in the bottom center of the float chamber, is absolutely clean as full must freely flow thru that jet before it can gain access to any other fuel passageway.
    ********************
    With no intention of insulting your intelligence, just a reminder to keep in mind............

    Einstein once stated that "The definition of insanity is doing the same thing over and over and expecting a different result."
    UPDATE....
    I ended up getting a carb from a blown engine from the local marine shop (I got lucky, free carb). Cleaned it up and transferred the jets from mine. Installed and started the engine. Problem solved!!!

    I did clean mine again and I think the flow through the small tube may have increased. Hard to say, such a small difference. I will try it in the future.

    Now I need to test it on the water with WOT. Hopefully I won't need to pump the bulb to get proper power

    Thanks again for your help !!

  23. #23
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    Default Re: carb issue on 2000 90hp johnson

    1) These carbs do not use the washer under needle seat so remove as this can bind needle.
    2) You are using the correct o-ring to seal body to throttle plate in the picture
    3) Make sure passage to inlet needle is clean
    4) And I am pretty dang sure you are missing a pull over tube as it should have 2 of the small brass tubes.
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  24. #24

    Default Re: carb issue on 2000 90hp johnson

    You are correct, no washer on needle seat is needed on this carb.
    Everything else is correct.

    Thanks

  25. #25
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    Default Re: carb issue on 2000 90hp johnson

    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  26. #26

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by Vin92 View Post
    UPDATE....
    I ended up getting a carb from a blown engine from the local marine shop (I got lucky, free carb). Cleaned it up and transferred the jets from mine. Installed and started the engine. Problem solved!!!

    I did clean mine again and I think the flow through the small tube may have increased. Hard to say, such a small difference. I will try it in the future.

    Now I need to test it on the water with WOT. Hopefully I won't need to pump the bulb to get proper power

    Thanks again for your help !!
    Took boat on the water. Idles nice but no top end power. Couldn't get on plane.

    Float Height question ......
    I setup my float height per the manual. Approx 1" from the gasket to the bottom of the float. This is not a 1" drop, much less. Does this sound correct ??
    Some say a 1" drop and others say 1" from the gasket to the bottom of the float. Big difference.

    Thanks.

    Vin
    Last edited by Vin92; 06-19-2019 at 01:59 PM.

  27. #27
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    Default Re: carb issue on 2000 90hp johnson

    Personally I never concerned myself with the drop figure. I sat the float as follows and let God sit the drop... never had a problem in 30+ years.
    ********************
    (Carburetor Float Setting)
    (J. Reeves)

    With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.
    ********************
    We occasionally have questions. If you fail to answer, it may affect ours.

  28. #28

    Default Re: carb issue on 2000 90hp johnson

    Quote Originally Posted by joereeves View Post
    Personally I never concerned myself with the drop figure. I sat the float as follows and let God sit the drop... never had a problem in 30+ years.
    ********************
    (Carburetor Float Setting)
    (J. Reeves)

    With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.
    ********************
    Thanks.
    That's the way I set it up before I measured the drop. Basically, ever so slightly off of parallel.

  29. #29
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    Default Re: carb issue on 2000 90hp johnson

    How did you set the adjustment needles? You cannot set these correctly on a hose or bucket
    Pappys Sales and Service
    Owner and Factory Certified Technician
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  30. #30

    Default Re: carb issue on 2000 90hp johnson

    Didn't touch the needle valves. Those are on the throttle body.

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