Question about 1991 Mitsubishi Mighty Max

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

1991 Mitsubishi Mighty Max 2D 4X4 V6-(FUEL INJECTED) Hi, My truck acts like its starting but it wont start. Its getting gas (i know this because i took off the fuel pump hose off the motor and it is spraying) So the pump is working (but i dont know if its pumping enough) I also put gas in the air filter hose it did pop! Now im going to try replaceing the fuel filter, if that doesent work i will check the injectors. then a fuel pump if needed. I understand that this truck needs fuel pressure so i dont know if its getting enough pressure. Please help! Thanks!

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  • Nick Vellis Apr 26, 2010

    i can hear the injectors when i turn the battery on but it seams like they are erratic some go off at times then start clicking again. When i put fuel down the air intake it almost started, it popped ran for about 5 seconds and quit. I took the fuel line off the engine and fuel was pumping out but i could put my finger over the tube and stop the fuel. So im guessing that there is not enough fuel pressure. I replaced the fuel filter. Filled the tank. Still no start. So now im thinking about dropping the tank and replacing the fuel pump sense that creates the fuel pressure. So my question now is do i replace the fuel pump or the ECU?



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

Posted on Apr 23, 2010


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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

1 Answer

1991 mitsubishi mighty max want start in cold weather but will when its warm outside what could be the problem?

if this is carb motor than it needs a manual choke that mounts on inside of lower dash, the kind you see on lawn mowers,,,push and pull.

Mar 11, 2011 | 1991 Mitsubishi Mighty Max

1 Answer

I'm doing a valve job on my 1991 Mitsubishi mighty max v6 3.0L 4x4. I recently replaced my ECU the truck sat in the woods for 5 years so im wondering what I should I replace while I have it apart....

The problem with the truck sitting so long with any amount of fuel in the tank is that it turns into varnish. You may have to drop the fuel tank to make sure it is clean. Also the fuel pump may be locked up from the varnish. Make sure all the fuel lines are clear before you reconnect them. You may have problems with the injectors too. I am guessing this is a fuel injected engine? If not, you may only have to clean out the tank, fuel lines and carburetor.

Oct 03, 2010 | 1991 Mitsubishi Mighty Max

1 Answer

Where is the Fuel pressure Regulater on a 1991 Mitsubishi Mighty Max 4X4 3.0L V6?....can i get a picture of the whole engine pointing it out if you can please.

I found this picture. At the front of the engine to the left of the round opening on the square intake. The glove is sitting on the fuel rail. At the front is the pressure regulator.

May 04, 2010 | 1991 Mitsubishi Mighty Max

1 Answer

No Fuel??? Not starting.

You have fuel flow but the question now is are the injectors pulsing. Given the year of the truck my gut says your ECU, Engine Control Unit, has failed. Mitsubishi had issues with the capacitors in their early 90's cars, trucks SUVs. I have been thru this with two monteros and one 3000GT, very common. To check your injectors rent a set of NOID lites from Autozone our such. Remove an injector plug and itstall a noid light. Turn the engine over, if no flash, no pulse. Remove the ECU and carefully open it up. Look for the capacitors, there should be 3, look under the capacitors on the board; if there is a grease like substance, often time it has a green hew to it, then the capacitor(s) have failed. It may be possible to replace the capacitors or simply purchase a rebuilt ECU. Be ceratin the MD number matches on the new unit.
Please let me know your results and if this had assisted you.
Thanks, Tom

Apr 23, 2010 | 1991 Mitsubishi Mighty Max

2 Answers


your going to have to pull back carpet and clean any liquid up and start your truck and watch for original source of leaks,have you removed the plastic cover of the heat work on the drivers side to see if the heater core is leaking and running over to the drivers side.

Dec 28, 2009 | 1991 Mitsubishi Mighty Max

1 Answer

1991 mitsubishi might max hard to start when its cold out side.the colder the it wont start at all and its real cold!

problems with the choke, to low fuel float level in carburator, timing to retarded or just problems with your battery or starter if it doesnt crank fast enough

Dec 08, 2009 | 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

1 Answer

1991 mighty max

If it is 4X4 and you re not going far. Put the transfer case in neutral. If it is 2X4 standard transmission, put it in neutral. If it is an automatic transmission you need to remove the driveline.

Jul 10, 2008 | 1991 Mitsubishi Mighty Max

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