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Desperately need tuning help!

Discussion in 'Suzuki Carry' started by rstickley, Nov 20, 2011.

  1. Jim Nelson

    Jim Nelson Active Member

    It really depends on how well you want it to run,if you want it to run like new you have to plumb it like new.These things are really screwy and the vac routing is dependant on the equipment on it.There are several threads here on different variations and if you find one similar to yours you might get it running well enough.
  2. spaner

    spaner Well-Known Member


    Everything you ever wanted to know about the Suzuki DD51t vacuum lines.

    This is post 122 and everything is here (or links are here), in this thread. If I can contribute anything to this site in 2014 it is to get nubes to stop posting new threads on vacuum line routing questions.

    Nube post history 1, 2, 3. AKA ranking. You have 3 posts under your belt (nube​).
    We are getting a lot of new members here lately, and I think that's great; this is a great site, with great members.

    Rule number 1,
    READ, READ, READ...then read some more. Then when you're just about sick of reading...READ SOME MORE. Then, you are just about ready to make your first post, to ask a question, but first, READ SOME MORE.
    (Instruction: USE GOOGLE SEARCH ENGINE "minitrucktalk [search parameter]")

    5 brand new members, in the last week have asked the same questions about the vacuum line routing for the DD51t, and HERE the answers are...

    Just read this thread...

    Sure, ask questions, but the result should be obvious for this site; when the answers are plain, and easily had, no one will give you shite about it, or berate you...(they are too nice for that here)

    Your post will just be ignored...a bad way to start off as a new member here.


    PS: Rule number 2,
    If your "uploaded" picture reads "MB", it's too BIG!!!
    A 1.95mb picture is SOooo big, that I can count the crabs, on the pubs, of your girlfriend, in the background of your picture...:sly:

    A 300kb picture is huge, and good enough. I can read the sparkplug numbers on an engine bay shot...:p

    The reason, IT HOGS the server storage space and processor. Soon, the K-man will just make all members have to sign up for a "photobucket" account, and there will be no pictures hosted here.
    Also, for a dial-up guy, a 1.95mb pic takes about 3min to be rendered.
    300kb, about 30 seconds.

    NUBE rant done...
    Victor Getov and Koyotekiller like this.
  3. spaner

    spaner Well-Known Member


    A little harsh for the nubes to read maybe (from a "nice guy" stand-point :p), but the senior members here know what it is that I'm referring to. Time-wasting, irritational post-linking, to clear the Activity-Board.

    "Stick it up my bum, kay?",
    "I don't know what I'm doing, so can you do it for me...please?"...:frustration:

    NO, WE CAN NOT, Sorry...:sly:

    "PLEASE???"; 5-times, in one week...:eek:
    That is NOT what this site is about.
    SHARING, sharing OUR knowledge; that is what this site is about, and has been, for many years.
    (Thanks K-man)

    Maybe you know nothing, but you just got out from under the truck, and you measured the rear leaf forward mounting bolt. It's an M12, by 122mm, grade 8. (guessing)
    Now you've got some "trading-credit", AKA, knowledge;...

    Got it? Understand now?...S-H-A-R-I-N-G...;)

    5-posts under your belt, and all questions, to which answers can easily be found in a post from 5-years ago...on this site, but you didn't bother reading-reaserching, hanging-out...BAD...bad-member, bad way to start here as a member; on a GREAT site.

    I bother to post this obvious revelation cu'z, if you haven't noticed, we've lost some very knowledgeable members of late; CU'Z THEY GOT BORED...bored with the activity stream.

    So nubes, if you're going to post, think first, and if you're going to ask, then ask well.

    I'll finish off this mini rant by closing the informational-loop of this particular thread.
    A lot of information I just don't give out, cu'z it can do more harm than good, in most cases.

    Assuming that you have everything "TIP-TOP"; doubtful as that may be...

    The "mixture screw" on the DD51t is NOT that at all. It is a "FINE" adjustment setting for the CO2/E-test only, and will do NOTHING for you, as far as tuning the engine for performance/economy.
    It's the vacuum lines that need to be in their proper places, with the restrictors and one-ways in place.
    "TIP-TOP" first, remember...

    Then, for some reason, or for some mod; there ARE adjustments that can be made to the system to enrichen/lean.
    First-principles, understand the system first, then you will see the adjustments that can be made; and they are LARGE. Large adjustments to the enrichen/lean are more than possible and easy, on the carbed DD51t.
    Jim, noted one some time back. The main plunger-diaphragm-needle. This is your MAIN fuel-flow setting.
    Where is the pin base set too?
    Very few posts linked to this setting, and a carb rebuild may have fubared you, or replaced it back to a factory setting. Are you aware of this setting? Then look at it, research/study it, adjust/mess with it. It is the MAIN mixture setting mechanism for the carbed DD51t (like a side-draft Harley, HO, Ho :rolleyes:)...NOT, the "mixture screw", of which, there is none; just the CO2/E-test "fine" adjustment.
    There, that should be more than enough but, if you are crazy like me, and you need to go WAY rich for some reason (like a supercharger...:p) the carb spacer, that red thingy...
    It has a restrictor built into the venturi of this particular Mikuni side-draft carb application.
    I removed 100% of it, in order to get 100% of this particular carbs' enrichment potential.
    MORE than enough for a 1 atmo boost application.
    No way that you would need that, but a slight grinding and removal of the restriction, would enrichen it for your particular needs.

    The air-intake as well.
    This should meet your needs for a small adjustment enrichen/leaning.
    Remember, "First-Principles".
    Like a "choke",
    A restrictive element, will enrichen the system, while a "full-flow" element will lean it.
    The opposit is also true for the back-side of the "plunger", and the factory restrictive element. A restriction on the back-side of the plunger will LEAN the mixture, while removing it, will renrichen it.
    Removing it via a dremel, will get you a setting that can-not be reversed. So be sure, or be bold.

    Regardless, it can be done.
    TIP-TOP, first though, and the reason to be a member of good standing; READ, READ, READ...then, read some more...:p

    Great members here, DO NOT, wear out their patience, or your welcome...nube

    Victor Getov likes this.
  4. 660LVPE

    660LVPE New Member

    rstickley, can you tell me where the other end of vaccuum port #6 goes? It seems I have nothing plugged there and I wonder if this causes my hesitation at mid-range...
  5. allproscotty

    allproscotty New Member

    u seem to be the go-to guy here. new member fron Canada. have a 97 dd51t. cant get it off fast idle unless i pull vac line off choke pulloff then its fine. runs up to temp no problem. fan switch kicks in so i know engine is coming up to op temp. any ideas? non-molested truck fresh off the boat thanks
  6. pepci

    pepci Member

    I once had a similar problem and it took me a couple weeks to figure it out and what I found was a small rock caught in the EGR valve not allowing it to open fully and that caused it to run in the same fashion as what you are describing here. Just another thing to check on.
  7. NorthernRadar

    NorthernRadar New Member

    Hi everybody. I am new to minitrucks and this forum. I have had nothing but trouble with my 1991 Carry, since day 1, actually, so after several different mechanics, I have been scouring forums to try and figure out my idle trouble. This seems to be the right thread for me, but I have noticed that most of the reference photos are missing. Is there a way to find them, or do I need to move on with my life?
  8. gdw4078

    gdw4078 Member

    I think you need to register to see pictures
  9. NorthernRadar

    NorthernRadar New Member

    I thought that I was registered. Is there another hoop that I need to jump through?
  10. Anne Sweeney

    Anne Sweeney Member

    About 4 weeks after I got my truck from the dealer, I took about 12 pictures showing vacuum routing around the carb because that was probably, I consider, the most intelligible thing to do. I also counted how many turns clockwise until fully set all adjustment screws so all I could bother someday is performing fine adjustments thru plug reading. I kept hard copies of pictures anyway.
  11. Merch

    Merch New Member

    Does anyone have these pictures saved that spaner is describing in this post? My computer says they have been removed. Thanks

  12. gdw4078

    gdw4078 Member

    Lineman1 likes this.
  13. Merch

    Merch New Member

    Could someone please help me with these adjustment screws I have circled. I would like to match them up with the numbers that spaner explains in this post. Thanks everyone.


    Attached Files:

  14. spaner

    spaner Well-Known Member


    So, I'm going to do it. I'm going to tell you how to lean the carb properly.
    If you are one of the guys that has made it this far in the thread, then your unit is probly "tip-top" at this point. "The screw", as I said, is for the E-test, CO2 fine adjustment and will do nothing for you.
    Consider your unit, winter, summer, and by this point, if you do this, I take no responsibility for the outcome. I swore that I would not, as some information does more harm than good.
    So be it; it's a 10 minute job.

    Understand the current condition:


    The adjustment; needle location:


    4-screws on top of the carb,
    pull the plunger and diaphram unit,
    on the bench, remove the diaphram and retainer,
    pull the needle unit as a whole,

    Our needle has no clip-slot adjustment positions,
    What it does have, is a lower washer/spacer-factory setting,

    [Pin sitting Lower = Leaner]--[For Mid-Range]

    Remove the washer from the bottom side [Point-End]
    Place washer on top of pin-clip [Stub-End]


    Reassemble--Takes 10 minutes and a phillips

    Lean-Rich-Optimal.jpg carb_needle.jpg
  15. Wheelie

    Wheelie Member

    So the screw in the middle of the vacuum ports is supposed to be closed? If not what is the factory setting? I read the whole thread thinking someone would mention this screw. Maybe I missed it but I can't find it. If I can find out what that center screw in between the vacuum ports should be set to it would really help me. Or maybe what everyones is set to on a good running truck?
    Last edited: Jul 12, 2017
  16. JInman

    JInman New Member

    This thread is very informative, unfortunately the adjustment procedure detailed nicely by Spaner some time ago mentions screws 1 through 7, however the pictures don't show up anymore so it's pretty difficult to figure out which screw is what in trying to follow this procedure. I am also wanting to set warmed up idle properly but not sure if the screw on the front of the carb is the correct one or not (it does move the throttle open, so assume that's it), but wish I could follow the instructions to the letter. I don't know what that middle screw is between the ports either - sorry
  17. Wheelie

    Wheelie Member

    Well I assumed the screw was idle mixture and sure enough it is. I set it to 1.5 turns out and fine tuned the idle to spec using the butterfly adjustment screw to around 950 rpm. The engine seems to be running very well now.
  18. KCCats

    KCCats Active Member

    Spanner Sir is there any way to re down load those pics for us Nubs?
    It seems no one new here can see them?
  19. Cole

    Cole Member

    KCCats I have been in the same boat. I believe after months of reading I have all the screws and associated numbers figured out along with spanner's description of the carb tuning in my own words. I took picures of my own carb for reference and will post them with a write up in the few days hopefully.
  20. KCCats

    KCCats Active Member

    Please do, I'll even pm you my Email perhaps you could email me the pics and write up?
  21. Cole

    Cole Member

    Okay here we go. I just want to say that the following information is just what I have gathered from other peoples threads (main Spanner! lol). I am not trying to take credit for other peoples work. I am hoping to just compile everything I have been reading over the last couple months. All pictures but one are of my own Carb and I have attached numbers to the screws, which I believe match up with descriptions and missing photos previously in the thread.

    As mentioned may times, in multiple threads, CARB tuning will only be easy/helpful if you have no vacuum leaks, correct routing and everything else correct. You can't tune a CARB to fix other problems!
    Also I am going to assume that your Choke is set up to begin with. You can find a lot of good information in the thread "Choke-idle is too high". There is no sense repeating that. However I will identify the screws.

    Carburetor adjustment screws

    Screw #1 - Idle-up Actuator Adjustment (This is for starting/restarting purposes. It holds the throttle above base idle. Like putting your foot on the pedal when starting the engine. As soon as the engine starts the actuator should retract and remove itself from the system until the engine stops.)

    Screw #2 - Accessory Idle Adjustment (This increases the engine RPM for when there is extra load on the engine aka Blower motor, Headlights, Rad Fan, Hydraulic Dump, etc. There is a control relay that operates a solenoid valve and uses Vacuum directly from the intake manifold to operate the actuator when the previous items are in use. Otherwise it is out of the picture on standby)

    Screw #3 - Base Idle (Rather simple. It adjusts the throttle to maintain the engines base idle approx 950 RPM)

    Screw #4 - Choke plate adjustment ( I borrowed this picture. It is directly above the thermal pusher pin on the side of the CARB. It adjusts the Choke plate position and thermal pusher pin is responsible for removing the Choke when the engine warms up)

    Screw #5 - Choke Idle (Again rather simple. This screw adjusts the RPM the engine will run at when the engine is in it's warming up phase. From what I have read approx 2000-2500 RPM. It allows the engine to warm up faster.)

    Screw # 6 - CO2 Fine Adjustment (Some call this the CO2 Fine adjustment as the manual describes adjusting is with a CO2 monitor in the tail pipe. Some call it the Fuel/Air mixture screw. Either way my understanding is that it doesn't accomplish much and I have yet to play with mine.)

    Carburetor Adjustment

    With engine cold the Choke plate should be 100% closed (adjusted by screw #4)

    Start the engine and the Choke plate should open to 85% via the Choke actuator. The Idle-up actuator should also retract. The engine is now warming up and the Choke RPM can be adjusted using Screw #5.

    At this point Screws #1,2,3 should be off their seats.

    Allow the engine to completely WARM up and the choke to remove its self from the system. Check that the other screws are still off their seats. If not make sure the actuators are in the proper position and back them off. Now the engine in running using Screw #3 base idle. If staring from scratch you may need to hold the throttle, up to this point, to keep engine running as base idle had not been set. If you are working from a Carb already in use then you adjust this screw to obtain the Base RPM of Approx 950 RPM (Without any lights, Rad fan, blower motor, etc on). I don't have a TACH yet so I use a portable hand held one pushed against the crankshaft. Shut off the engine and restart and confirm the engine is at base idle.

    The engine has now warmed up in the Choke phase and is running at it's base idle.

    Now to adjust the idle-up actuator. Adjust the screw #1 so that it is almost in contact with the seat. When the engine is turned off it will contact the seat and throttle up the engine. This is responsible for the momentary higher RPM when you initially start a previously warmed up engine. I found I needed to make a couple small adjustments to this after cycling the engine a couple times to find the sweet spot. I do not have an actual number for this but it would be around 1500-2000 RPM give or take.

    Finally we come to the Accessory Idle adjustment screw #2. With the engine running and warmed up and the previous steps complete make sure no accessories are on, the actuator is not retracted and engine is at base idle. Now turn you lights or blower motor on full and the actuator should retract to open the throttle. Now adjust screw #2 toward the seat and keep adjusting until you start to raise the engine RPM. This should be set at approx 1500 RPM. Now turn all the loads off and the RPM should drop to base idle. Turn them back on and RPM should increase.

    Congrats! Your Carb should function as is should.

    I also found a lot of good info in the thread - 93suzuki Carburetor (carefull there are two)

    Hopefully this clears it up for some of you. I felt it was my time to help after months of lurking and reading!lol I am not an expert just very obsessive in the stuff i am interested in.

    Attached Files:

    Last edited: Aug 6, 2017
    stecal, Koyotekiller and Merch like this.
  22. KCCats

    KCCats Active Member

    Last edited: Dec 30, 2017
  23. jaxondes

    jaxondes New Member

    Excellent post Cole - thanks. I have just purchased a 93 Carry that wasn't running right when I got it, and I'm still struggling to get it to not bog in the cold. I'm going to take the carb off and clean it, then follow your tuning. Where are you located? I'm up here in Northern SK.

  24. Cole

    Cole Member

    I am in Northwestern Ontario close to Manitoba. I also had a bog in really cold weather. I found that is was running lean in that weather since the low idle jetting couldn't keep up. Cold weather = more fuel! I got mine to run a lot better buy adjusting the accelerator pump linkage. I took my carb apart and it was so clean it looked bran new so I knew that probably wouldn't be the problem. The accelerator pump linkage is located on the right side (front) just under the base idle screw. Unfortunately you have to unbolt the carb to really get at it. I turned right up to give the lever maximum throw (up and down) this gives it a larger shot of fuel when depress the pedal. Take a look. It might not be your problem but it helped mine run a lot better in the cold.
    Okiefirefighter likes this.
  25. Cole

    Cole Member

  26. jaxondes

    jaxondes New Member

    Interesting, thanks guys!
  27. milmor88

    milmor88 Member

    Here is some useful diagrams and such that i found searching this forum, I got my mini tuned last night and the info from cole and others was priceless...here is picture of 3+2 2+3 and a picture of the actuators and what they do, none of this was my own but i had just saved these as i searched away

    Attached Files:

    Koyotekiller likes this.
  28. milmor88

    milmor88 Member


    I've read this post a while back and just got to switching my check valve from black part towards carb to dizzy instead, but most of the pictures i have found as well as the new engine that i got had it the other way. I would think like you said that you would want the carb to be able to pull vacuum on the dizzy, if it's reversed it's about pointless, but i have seen so many pictures on here with it the opposite way see the picture from post #4 from https://minitrucktalk.com/threads/dd51t-vacuum-puzzle.15401/

    Attached Files:

  29. Travis K.

    Travis K. New Member

    Hi everybody!
    Random discovery recently. I have an '87 Suzuki Carry and was frustrated with the cost of new points. Used to own a '67 Datsun 1600 Roadster and had an old set of points for it laying around. I'll be damned I'd they weren't an exact fit, in stock, at Napa WAY cheaper! Thought I'd share :)
    Koyotekiller and fmartin_gila like this.
  30. fmartin_gila

    fmartin_gila Well-Known Member

    Now that is what these forums are about, sharing some good info. Mine is EFI and everything is computered but there are many others who will appreciate this info. Thanks for posting.

    Alan Hairston and Koyotekiller like this.

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