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!
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
Testimonial: "Thanks! I will try your ideas and get back to you shortly!!!"
You mention you could hear the injectors? I expect the engine was being turned over and you could hear the click of the injectors? Also I believe the fuel pressure at start is @ 50PSI and runs @ 30PSI. Another way to check the injectors: if after turning over are the spark plugs wet? (flooded) It would appear you have spark as when you some gas in it, it did run for a brief moment?
I would not expect touching that line to the battery would damage things; however with computers one can never tell. If you do need a new ECU you can try AutoZone or some other national chain.
Please let me know what you have to see if we can narrow it down.
Thanks,
Tom
If the injectors are firing it would appear the ECU is good. Could you check the plugs to see if any fuel is getting in to the cylinders. Crank the engine over for 3-4 seconds, stop, pull a plug or two and look for gas, plugs may even get flooded. If no gas entering and injectors are firing off I'd say the fuel pressure is low; I just confirmed with my manual: with the 3.0 V6 the fuel pressure should be @ 38PSI, with the vacuum hose disconnected from the fuel pressure regulator the pressure should be @ 47 to 53PSI. Also check the Pressure regulator, this is the piece that bolts to the fuel rail assembly, the return fuel hose connects to it, remove the vacuum line that connects to it, if the vacuum line has gas in it this regulator has failed. It is very possible then that raw gas may be headed right back down this vacuum line, thus low pressure. In checking my manual I am uncertain of accessing the fuel pump on the Pick-up. On the Montero's there in an access cover under the rear carpet. Once the rear carpet is pulled back you simply remove the access plate and you're looking down on the tank with the fuel pump location, no need to drop tank, just pull pump from there. Does the pick-up have an access plate to the tank/fuel pump in the bed?
Thanks,
Tom
Good luck with it, please let me know if this may have assited; always hoping I learn a bit more. I'd try with the regulator first, then see if fuel in cylinders, lastly check the fuel pressure. Hopefully one of those will give you your troubles and answer.
Best regards,
Tom
The injectors could very well be plugged, however my gut still goes back to if the injectors are firing properly. Any chance you could rent a set of NOID lights from an AutoZone or such parts store. Typically you pay the $30 or so dollars and when you return them you get your cash back. I go there because of the year of the truck I have owned two montero's one a 90 the othe a 91 and one Dodge Stealth (our son's), a 93, that seemingly had same issues and in the end it was the ECU. You could inspect the ECU by removing it and carefully opening it up to look at the capacitors; if you see a liquid under them (looks like pale green grease) the capacitor(s) are bad and the ECU requires either rebuild or replace.
Your thoughts?
Thanks,
Tom
As you noted crank her over for a bit, then remove a plug or two. If no gas either plugged injectors or no injector pulse. If no gas my two cents are on no injector pulse and the ECU.
Please keep me informed on how it is going.
Thanks!
Tom
Im pretty shure the injectors are fireing, i put a voltage tester on them and it said they had power. I hear a clicking when i crank the engine for 5 seconds then stop but leave the battery on. Are those the injectors? I will check the plugs for fuel. This truck has been sitting for 3 years and had very bad gas in it when i started working on it so im pretty shure the injectors are plugged.(i did change the fuel filter) Also i have 1 bad clyinder would that cause the truck not to start??? im really hoping not. I pretty shure the ECU is good because the truck was running great before it was parked. Thanks for your help, Nick
Im pretty shure the injectors are fireing, i put a voltage tester on them and it said they had power. I hear a clicking when i crank the engine for 5 seconds then stop but leave the battery on. Are those the injectors? I will check the plugs for fuel. This truck has been sitting for 3 years and had very bad gas in it when i started working on it so im pretty shure the injectors are plugged.(i did change the fuel filter) Also i have 1 bad clyinder would that cause the truck not to start??? im really hoping not. I pretty shure the ECU is good because the truck was running great before it was parked. Thanks for your help, Nick
NIck, With age of the fuel it may have very well gummed up the injectors. With one bad cylinder she would still fire, run poor, but still run. My buddy purchased my first Montero, drove it out one day, parked it for 4 hours went to start and no dice... the ECU went bad. Just sitting, with time and variable temps could make the old capacitors go bad. To hear the injectors you typically need a mechanics listening device (looks like something your doctor uses to hear your heart, less a different end to it ) My opinion on the old ECU is not if but when it will go bad. If you can I'd try a set of NOID lights or look for fuel in the cylinders. If you have fuel, spark and compression only thing then could be timing.... did timing belt slip?
My two cents still say ECU....perhaps.
Thanks,
Tom
Nick, yes the capacitors alone can be replaced. I have the capacitors and would be happy to send you a set no charge. T tried rebuilding an ECU once but the board was to fried out from the leaking capacitors. Also you can test your ECU (stupid of me, I should have gone here first!) where your computer test plug is (In the montero down by front passenger feet) you can use an anolog test/multi meter. There are two points where you hook the meter up and the ECU sends back a type of morris-code showing what may be bad... such as sensors or such, the ECU has its own code if it is bad. Please get me your email and I'll scan some documents on how to test. It is very easy to do and requires no tools (other than the meter.
Thanks,
Tom
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Today I turned the battery on and I could hear the injectors. Also, the guy that had the truck before me touched the end on the hose(the metal part) to the battery and it sparked. it hasen't ran sence. Could that make the ECU quit? if so, where can i get a new ECU? and how much?
-Tom Yes 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?
Cool. No this truck does not have a access plate. I will probably have to drop the tank.
Thanks Tom i will get back to you once i try your ideas Thanks!
Tom, I filled the fuel tank and it still didnt start. I checked the fuel pressure it is at 50psi. when its cranking. This tells me the fuel pump is ok. I also checked the regulater there was no fuel in it. So regulater is ok. I still need to check the plugs for fuel. Anything else i can check?? If not i will tow it to the shop and put it on a computer.
Im thinking that the injectors are pluged.
Tom, If the ECU is bad can i just replace the capacitors? or do i have to replace the whole ECU? I will try to rent a set of NOID lights. First i will check the plugs for fuel, then check if the injectors are plugged, but i cant check the timing because the truck doesn't run. i don't know if the timing belt slipped because i haven't seen this truck running. I bought it non-op. Lastly i will put it on a computer. And do you know how to take the injectors out? so i can check if there plugged. And the check engine light is on so im pretty sure that whatever is wrong its stored in the ECU.
Cool thank you Tom my e-mail is [email protected] (the L is a lower case tho) i will test the ECU when i get the e-mail Thanks a bunch, Nick
Tom, today i took out the ECU and took the lid off. Its clean but by the capacitors there is a brown grease like liquid but its dry and sticky. It looks like it came out of a little tiny hole. It didnt eat the board away. So i dont know what to think. A capacitor might have leaked. I can i will send you some pictures on your e-mail.
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