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Doug
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8538
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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My 1992 Mitsubishi Montero four wheel drive will run couple

Customer Question

my 1992 Mitsubishi Montero four wheel drive will run for a couple days then I'll go out and try to start it will crank but wont start if I leave it the next day it'll will run what could it be
Submitted: 1 year ago.
Category: Mitsubishi
Customer: replied 1 year ago.
it runs great for a day or two then it cranks over but wont start then when I try it the few hours later it starts and runs great
Expert:  Doug replied 1 year ago.

Hi,
This can be a very difficult and frustrating sort of behavior to resolve when it is intermittent like this. The best thing you can do is try to be prepared with some spare time when you go to use the vehicle in case it acts up... then when it does you can start checking for problem areas.

The engine is going to run as long as it has Spark, Fuel, and Compression.... any loss of one will prevent the engine from running. We can rule out compression right off the bat as there isn't really anything that is going to cause a sudden loss of compression nor would it come back afterward in most cases.
So when the problem occurs we would want to first check for spark operation. If there is no spark, then we would want to check our crank sensor operation. The crank sensor is on the front bottom of the engine behind the pulleys, but has a pigtail leading up the engine to a three pin connector. There will be 12V, 5V and ground there when unplugged with the key on. With the sensor plugged in and the 5V wire back probed, you should see on/off 5v-0v-5v-0v operation as you rotate the engine by hand (not by starter). If you do not see the on/off behavior then the crank sensor is failing... a common fault area. If you do see it then you would want to look into coil or ECU issues.
If you do have spark then you will want to check your fuel pressure to verify fuel pump operation and your fuel pulse to verify fuel delivery to the cylinders. Fuel pumps are common to fail in this nature where it will suddenly just not work then a day later work OK. This is similar in nature to when a power window motor sticks intermittently. You can often slap the bottom of the fuel tank when this happens and free it, though not always.
The fuel injector operation is a bit less common but on this generation it was somewhat common to see the ECU fail in such a way that the injector drivers would stop working. This did not usually happen many times though... it was usually 3-4 times and then it was done and would not work again. This is related to the same condition that would cause your spark drivers to die on these.... the capacitors were failure prone inside the ecus. If you can find someone that does low level electronics repair they can be fixed luckily, and usually for not too much money.

For the most part though you aren't likely to get that far... most often intermittent crank no start on these will be either no spark from a failed crank sensor or no fuel from a seized pump.

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