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Thread: 1991 Mighty max

  1. #1

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    1991 Mitsubishi Mighty Max
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    I.D.K.?

    1991 Mighty max

    Why does my truck start up then die right away?I had the catalytic converter replaced in July.My truck ran great ,for a week.I started my truck and then it died right away.I had replaced the fuel filter before the catalytic converter.Along with plugs ,battery,fuses, then a new fuel pump.I even got a new part from a local auto store.For the fuel relay thats on the passenger kick panel.It did the same thing.I don't know what else to do.I love this truck.What is causing it to die right away?

  2. #2

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    1990 Mitsubishi Mighty Max
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    Did you do anything that might have changed your timing? Is the check engine light on by chance? A little more info like mileage, how much it was driven since tune up and reason for cat replacement would be help.
    1990 MM 4x4 3.0
    1991 MM 4x4 3.0 Diamonte
    1994 MM 2wd (work in progress)

  3. #3



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    What lush90 said or could be a bad module in distributor. If it is carbed, might try trickling gas into carb to see if it stays running that way.

  4. #4


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    1992 Mitsubishi Mighty Max
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    1991 should be fuel injected...ECU?

  5. #5

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    1990 Dodge Ram 50
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    Maybe loose connections on battery cables, could be corroded inside the terminals. Change them both, ground and power, be sure to clean the grounds until shiny. After that, look at changing the ecu or the little black cube near the distributor- ie ignition module. or TPS. thats my guess. Good Luck

  6. #6

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    1990 Mitsubishi Mighty Max
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    My truck is doing the same thing. It backfired one time through the intake the other day and started running worse and worse and finnaly got to where it would start up and idle for a few seconds then die. I thought it had maybe jumped time or something so I took it all apart and it looked like it was out of time. I ended up replacing the balance shaft belt because it was all dry rotted and then put everything back together and it fired up and did the same thing.

    It would idle for a 4-5 seconds then die again. It did this two or three times and then now it will start up and then die right away. It don't even try to idle.

  7. #7

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    Quote Originally Posted by vaprobe87 View Post
    My truck is doing the same thing. It backfired one time through the intake the other day and started running worse and worse and finnaly got to where it would start up and idle for a few seconds then die. I thought it had maybe jumped time or something so I took it all apart and it looked like it was out of time. I ended up replacing the balance shaft belt because it was all dry rotted and then put everything back together and it fired up and did the same thing.

    It would idle for a 4-5 seconds then die again. It did this two or three times and then now it will start up and then die right away. It don't even try to idle.
    your cat is probably clogged or melted.
    When mine backfired it blew a melted hole through the cat, I figured it out when I was chasing down a rattle in my exhaust that turned out to be melted porcelain 'marbles' that had made it all the way to the muffler.
    I knew daredevils and I ain't got nothin' against them, ........it's just they're all dead.

  8. #8

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    1991 Mitsubishi Mighty Max
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    I.D.K.?
    No i didn't do anything that i know of that changed the timing.Yes the check engine light is on.The truck was old and i have no clue about the reason for the cat to be replaced.It just started not having any power when i drove.So i took off the cat and muffler.Fired it up and it had power like i peeled out.So i bought a new one.Had Holiday muffler put it in for me.I always change the oil in my truck.Yes it's fuel injected.

  9. #9

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    I.D.K.?
    oh yea when i step on the gas it doesn't even rev,it just die's .But i heard a click sound down by the relay in the floor board.and everybody tells me its supposed to do that.But i never heard it do that before until it started then died.

  10. #10


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    My money is on the ECU...bad capacitors...Known issue

  11. #11

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    1994 Mitsubishi Mighty Max
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    damn rubycon capacitors, I changed mine out with panasonic

  12. #12

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    1990 Mitsubishi Mighty Max
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    Could be dirty EGR?
    1990 MM 4x4 3.0
    1991 MM 4x4 3.0 Diamonte
    1994 MM 2wd (work in progress)

  13. #13



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    1989 Mitsubishi Mighty Max
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    4G63-T
    Josh
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  14. #14

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    I think I may have my problem fixed now. I will just have to wait until all of this damn snow melts to test drive it though to make sure.

    My brother has owned a few of these trucks so I explained my problem to him and told him I thought I needed injectors and he said one of his trucks did the same thing and it turned out to just be a timing issue. I told him I thought my timing belt may have slipped before so I had already replaced both belts and set the timing but it still would not run. He said that when he changed the belt on his it was hard to get back in time correctly so I had him come over and we messed with the timing some and it fired right up and ran. He adjusted the TPS some and it is running and idling better than it has since I owned it.

    As far as we could figure it probably did slip a few teeth when I was driving it and then when I changed the timing belt it must have gotten off by a few teeth when I was putting the belt back on and ended up about the spot. I guess I should have double checked everything before putting the timing cover and everything back on but it was around 20 degrees outside and I was working with a flashlight when I did it the first time LOL

  15. #15

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    it was around 20 degrees outside and I was working with a flashlight
    Good lord! No one is going to hold Haste against you for this one!

    And glad everythign turned out alright.
    The greatest gift you have to give to the world is that of your own self~transformation.

  16. #16

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    Quote Originally Posted by LSR Mike View Post
    My money is on the ECU...bad capacitors...Known issue
    I'm with LSR Mike on this one. My 90 Max with the 2.4L manual was running, but terribly out of tune. i had put on a new head, exhaust manifold (old one was cracked), new O2 sensor and new exhaust incl brand new CAT. Still ran like crap until one extended run I got out and felt massive heat coming from just behind the cab - the exhaust became super heated from running way too rich.

    I always dismissed the ECU because "if it ran, the ECU must still be working". Well the capacitors indeed had leaked causing the rich idle condition. I shipped it to one of the many repair palces common in FL and had it back in 3 days for like $150.

    It'll take you 10-15 min to pull the ECU, remove 4 screws from the case and open it up to verify the condition of your capacitors.

    The truck runs a hell of a lot better know but still have flickering CEL from other things (see my other thread). but in the end that super heated CAT only last a few hundred miles before the itnernals disintegrated into chunks and rattled aroudn like mad. That CAT lasted only 1000 miles before I had to buy a new one. Check your ECU or just send it to be serviced unless there's evidence it was already rebuilt.

    If the capacitors are let go for too long, it will not only run like crap destroying exhaust components, but the leaking capacitors can and will eat away at the board and eventually it will be beyond repair.

    Good luck

  17. #17

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    This time is about the duration the electronics last. I third the motion.

    Hi, Jim.

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