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Thread: Mx32 4m-g

  1. #1
    Join Date
    Mar 2011
    Saskatoon, SK

    Mx32 4m-g

    Got an mx32 for the girlfriend. Engine runs like crap. It is not a spark or fueling issue as I've resolved those. Singled it down to the carb. Went to install a brand new factory replacement that doesn't quite have the same vacuum hookups. This engine has an ancient belt driven air pump to suck exhaust gasses and pump them into the intake. I plan to delete as much of this crap as possible. My main questions are;

    What vacuum components are essential, what can I delete?
    Choke plate seems to stay closed unless i manually jam a screwdriver in there to hold it open. The wiring connecter was a different size so I have yet to splice the old end on. Does the wire going into the factory harness normally hold the choke open? If not i'll have to just bypass it and tune it without a choke.

    Also any information on tuning these old carbs or these old engines would be helpful. I'm not used to this old tech.

  2. #2
    Join Date
    Jun 2004
    Victoria, BC
    Id almost bet that theres no-one on here with 4M experience.. you MAY find someone on one of the supra forums.. I dont know if the first gen supras even came carb'd though..

    Also not sure what vac stuff the carb itself might require.. might've been an idea to go weber rather than a factory reman.. but whatever..

    Really, all you'd have to leave on, as a guess..

    Brake Booster
    Cruise Control (assuming a its vac diaphragm.. which may be hosed anyways?)
    Vac advance on dizzy.. (if present)

    Im assuming the choke is electric? So the choke plates would be closed until the motor is warm, yeah? make sure you've got 12v on the choke power line..

    also.. other M engines will mechanically bolt in place eh.. Using the 4m's pan and pickup you should be able to drop a 5MGE in with some fuel piping and some wiring.. if all you're looking for is a more reliable smooth daily..


    '87 AE86 - GTSR5 - Daily Driver
    '72 RA21 Celica - 'Ill build it one day'
    '73 RN27 Hilux - Restomod in progress
    '80 MX32 Cressida - Next in the project queue
    '91 SV25 Camry All-Trac - Winter DD

  3. #3
    Join Date
    Nov 2008
    Quesnel B.C.
    Wow i dont think many of us are used to these carbys. What are the chances of making an adapter and installing a webber?

    P.s. either your hate your gf or shes a keeper.
    81,84,87, 88 toyota cressida, 84 bj60, 85 bj60, 86 hj60soa, 71 datsun 521 pickup

  4. #4
    Join Date
    Mar 2011
    Saskatoon, SK
    So I disconnected everything vacuum related that isn't needed. Spark advance, dash pot, pcv and booster are all hooked up. I made sure there are no vacuum leaks. Set the engine timing to 10 degrees with a timing light. Got it running half decent until rust started plugging up the fuel filter. So I took the filter off and dumped out some of the rust and dumped some fuel from the good side of the filter into the carb to fire it up and prime the fuel system in the process. My girlfriend saw me do this. So after that it ran again and fuel flowed through the filter. So I park the car and tell her not to drive it. What does she do, gets it stranded. So I go look at it, the fuel filter is cracked and she put it on backwards, so all the rust is now pushed into the carb. So I then tell her what she did and commenced to pull the fuel tank, and pressure wash it out, dry it, and vacuum all the rust out of it. I replaced the fuel filter with a cleanable glass one. I took the carb apart and cleaned all of the passages and re assembled. Filled up the tank with new fuel. Fired it up and it ran. Still ran like **** though but stayed running. I have to set the idle at around 1300 or it stalls out. It pops every few seconds like a misfire. I watch the idle mixture in the carb and it looks good, and it looks like the metering rod is jetting the right amount of fuel under throttle. Then as I tune it half decent, its driving home normally, accelerates good under throttle and sounds good also. Then out of nowhere it starts losing power like the battery is dying or its not getting fuel and falls flat on its face. I tried cranking it but it fires a few cycles and dies. I got my friend to come give me a boost and while the cables are hooked up same ****, stumbles and falls flat on its face, i watch fuel come out of the idle port, so that rules out it being a fuel issue. Just left it at the parking lot and got a ride home.

    This car is turning into a total basket case.

    Im ruling out mechanical issue, because if it was a valve or piston issue it would run like **** all the time. Only thing left is electrical. I know the coil is putting out juice because all the plugs are firing decent and i watch the spark jump on the wire. I have an intermittent starter solenoid issue as well but im thinking its just going bad and is a separate issue all together.

    I guess ill have to go back with a volt meter and start checking **** over. I would hope that there isnt a computer or something shutting the coil down. I dont really know how the coil or electrical system works because i cant find a diagram on this old car. Ide really like to just get this engine running , like i didnt think an old carb engine would be such a difficult **** to diagnose. Its getting to the point where I want to rip that engine out and throw it in the bush and replace with 1uz. But thats an entirely different can of worms
    Last edited by S3dan; 10-09-2014 at 11:22 PM.

  5. #5
    Join Date
    Aug 2010
    Toronto, ON
    Maybe its a relay issue?
    I had a relay that was going bad, and it would work....heat up and fail....was an intermittant thing. I don't know....?
    I have hanes manual for the 4m somewhere....I'll look tonight and see if I can post the electrical diagrams for you.
    1979 Cressida JZX3 VVTi

    2econd Heart Garage

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