Question about 1990 Mitsubishi Mighty Max

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Engine light and dont run

I have a 91 mighty max with fuel injection. the truck runs great until it gets warm and the engine light comes on and the the truck revs up and down and will only tac about 1000 rpms. changed plugs, wires, cap, and button. i have also changed fuel filter and gutted the catalytic converter. any suggestions or does anyone know how to get the codes for the check engine light?

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  • cwj83 Oct 12, 2008

    yes no vacuum leaks.


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Have you checked for engine vacuum leak and tested or checked airflow meter

Posted on Oct 09, 2008

  • tony yeatman
    tony yeatman Oct 13, 2008

    Is the pcv working .Not sure with your model but its usualy located on the top of the rocker cover .pull it out with the engine running engine should react to valve bieng removed also with engine running put your thumb on and off the end of the valve if no reaction you need to replace.the reaction should not be a delayed did you check for the vacuum leak?


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Mitsubishi mighty max

If your vehicle is fuel injected, Which I suspect that it is; It is HIGHLY DISCOURAGED to pump the accelerator pedal while starting--- This can cause a fuel flooding condition.

Nov 12, 2013 | Cars & Trucks

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I have a 1991 Mitsubuishi mighty max truck . The truck runs fine until I drive for about 1 mile and then the check engine light comes on and the truck starts shaking , but does not lose power.

Hi, I own an 86 Mighty Max truck myself. Is there anyway you can get the code number for the engine light coming on. It could be many things that cause this problem. Fuel filter, EGR, Clogged Catalyst, Sparkplug Misfire, Cracked Distributor Cap, the list goes on. It needs to be determined if the problem is fuel or electrical related to help diagnose the problem.

Oct 13, 2013 | 1991 Mitsubishi Mighty Max

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Truck wont start but spray a little ether in it and it will run until the ether is gone. I unhooked the fuel line on the fire wall and it only had gas come out of it when I cranked the motor over. I think...

When the key is first turned before cranking, the fuel pump comes on for a few seconds to prime the fuel system and bring it up to pressure and then shuts off. When you crank the engine, the fuel injectors start to function causing the fuel pressure to drop. So that's why the fuel pump kicks on while the engine is cranking and it will remain on until the ECM sees that everything is in working order and then commands the fuel pump to remain on until the ignition is turned off. Is this a 4.3L Vortec Engine? If so, the (CRAB) injection assembly under the intake is faulty. It looks more like a spider than anything else. Be sure that you have adequate amount of fuel pressure because the (Crab Injection System) won't work at all. If it's an eight cylinder, may need to use a injector noid light. It's a special design light that plugs into the injector harness connector and lights up in pulses when engine is cranked. If there is no light, trace and check all wires leading from injector harness to ECU. Hope This Helps.

Oct 02, 2013 | 1992 Mitsubishi Mighty Max

1 Answer

Where is the fuel filter on 1993 mighty max

The fuel pump is located in the fuel tank, and part of the Pick-up/Sending unit.

Jan 21, 2012 | 1993 Mitsubishi Mighty Max

1 Answer

1994 Mitsubishi Mighty Max, 2.4 injected. Truck would start but idle way up then down almost stalling. After warmed up it would idle decent and drive, but under load it had no "pull" and...

Hello brian..these are great little trucks, i have a 87 (hitachi carb) with over 300k on it---still going strong and gets good mileage. Sounds like a fuel delivery problem on yours--- You can test the fuel pressure and the pressure regulator with a manual gauge...autozone has loaner tools if you dont have a fuel pressure tester. You should have aprox 36 psi ---remove the vacuum line on the pressure regulator with the engine running, the pressure should come up about 5-10psi, if it dont the regulator is bad. (Make sure there is vacuum on that hose) Make sure the MAF sensor is clean, if dirty clean it with MAF sensor cleaner, don't use brake cleaner.

Check for vacuum leaks around the manifold and emissions hoses...a good way to do this is with carb cleaner...spray it on the areas you are checking, it engine rpm change, you found the leak.
Also check the coolant temperature sensor, if it is out of range it will send a false signal to the engine controller, the controller will not open the injector circuit to squirt enough fuel under a load.

I hope this helps & good luck with your mighty max.

Aug 27, 2011 | 1995 Mitsubishi Mighty Max

1 Answer

1991 Mitsubishi Mighty Max 2D 4X4 V6 3.0L No Start.

you can get pressure specs from your local parts dept, and check injector signal with a noid light

Apr 23, 2010 | 1991 Mitsubishi Mighty Max

1 Answer

91 mighty max wont start when cold

Next time when cold and it will not start remove a spark plug or two and see if the engines flooded. If so there are two things that come to mind; 1, worn injectors, leaking as engine sits with time causing difficult starts 2: bad oxygen sensor, if failed engines tend to run rich and the ECU may have your injectors pump heavy amounts of fuel to keep from running lean; often times you'll see poor fuel MPG if O2 sensor failed.

I hope this may have assisted you,

Oct 30, 2009 | 1991 Mitsubishi Mighty Max

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