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Doug C.
Doug C., ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 6403
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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Mitshubishi Galant: I have a 2000 mitsubishi galant with the

Customer Question

I have a 2000 mitsubishi galant with the 2.4l. We bought the car under the assumption that all it needed was a fuel pump. Well we went and replaced the relays for the fuel pump and MFI, both under the hood and the two relays that are in the passenger compartment to be safe. Still had no fuel pump kicking on. Next we took the access cover to the fuel pump off and took my multimeter and checked for power coming into the fuel pump and got nothing. I took the fuel pump out of the tank and took jumper wires and ran 12v to the pump and it runs so the fuel pump is good. I am at a loss on what could be the problem. My only experience with this issue was with my mustang and it ended up being the ECU not sending the signal to the fuel pump. Can anyone give me any guidance on this please?
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Doug C. replied 1 year ago.
Hi,

The fuel pump is driven by the crank sensor.

When the computer sees RPM signal from the crank sensor, it sends a ground to the secondary fuel pump relay. This allows the current from the primary fuel pump relay (powered by the ignition switch) to pass to the fuel pump.

In nearly all cases of no fuel pump operation, where the pump can be verified out of the vehicle (no melted connector on the pump housing, etc), the problem comes down to either an issue in the crank sensor or a wiring issue on the fuse panel in some rarer cases.


So with all that being said, are you able to verify RPM signal from the crank sensor via scan tool?
Customer: replied 1 year ago.

Unfortunately no i am not able to do that. is there any way to do that with a multimeter?

Expert:  Doug C. replied 1 year ago.
Sorry if you got that last post, I misread a portion of your question.

If you place your finger on the fuel pump relay while a helper cranks the engine, do you feel the relay click when the engine begins cranking?
Customer: replied 1 year ago.
All three relays under the hood click when you turn the key.
Expert:  Doug C. replied 1 year ago.
I am only interested in if the fuel pump relay clicks when the key is in the Start position.... no interest in the others. If you need to know which one is the fuel pump relay let me know and I can get a diagram for you.
Customer: replied 1 year ago.
The relay doesn't click when the engine is turning over.
Expert:  Doug C. replied 1 year ago.
Thanks.

Please go to the crank position sensor connector, which is the three wire connector at the front corner of the valve cover, just in front of the oil cap area.

Use your meter and check each of the three wires for voltage with the key on. Let me know what your readings are.
Customer: replied 1 year ago.
With the key on ir in start?
Expert:  Doug C. replied 1 year ago.
Just On for right now.
Customer: replied 1 year ago.
Blk - 0v.

Red - 12.3v

Green with red stripe - 0v

Also the car will run briefly with fuel put in the intake
Expert:  Doug C. replied 1 year ago.
Thanks.

Unplug the crank sensor connector and check the Green/Red wire again with the key On and see if you still have 0V even unplugged, or if you get a different reading.
Customer: replied 1 year ago.
Unplugged its reading 5v
Expert:  Doug C. replied 1 year ago.
Thanks.

Please plug it back in, then measure the reading while cranking the engine. The reading may fluctuate, if this is the case do your best to describe the fluctuation.
Customer: replied 1 year ago.
It bounces around at first from 1.8v to 2.9v. Then after cranking for a few secs it stays above 2.6v.
Expert:  Doug C. replied 1 year ago.
Hmmm.

Full the fuel pump relay out and tell me how many pins have voltage with the key On.

graphic
Customer: replied 1 year ago.
The two pins closest to the inner fender have 12v
Expert:  Doug C. replied 1 year ago.
Thanks.

One last time, feel that relay to see if you can feel it click when cranking the engine.
Customer: replied 1 year ago.
No clicking when cranking
Expert:  Doug C. replied 1 year ago.
Thanks.

Last thing to check.

With the fuel pump relay removed, use your meter to check for ground on the other two pins that did not have voltage previously. You can either set your meter to continuity/ohms and hook one lead to ground and the other to each pin, or set to DC Volts and hook one lead to battery positive and the other to each pin.

Tell me if you have ground on either pin, both key off, key on, and cranking.
Customer: replied 1 year ago.
The pin closet to the firewall has no continuity to ground in either key position

The pin closest to the front only gets continuity to ground briefly with the engine cranking, none in on or key off
Expert:  Doug C. replied 1 year ago.
Interesting!

As I mentioned before, the computer activates the fuel pump when it detects RPM signal from the crank sensor. This is why you are only seeing ground on the one pin in the cranking position.

Two follow up questions....

If you hold the Start position and keep cranking, does the ground maintain?

Have you reinstalled the fuel pump and plugged it in?

Thanks
Customer: replied 1 year ago.
Holding in the start position the ground holds for about a sec then goes away.

I haven't reinstalled the pump because its disassembled as I was only going to replace the pump itself and not the hole assembly.
Expert:  Doug C. replied 1 year ago.
Thanks.

I asked about the pump, because the other pin (with no ground) was checking the circuit through the pump.... that is the output to the pump, however disconnected continuity would have checked from the pin through the pump and to ground. This explains why we had no ground on that pin, which was my reason for asking. Obviously if it is unplugged that is the reason for no ground there and not a concern.


At this point, you are going to need a scan tool to go any further to verify the crank sensor 100%. You should have ground full time while cranking the engine, not just for one second. The only things that are going to prevent that are the crank sensor, the computer, and the wiring between. We can fairly safely rule a broken wire out, since you do see ground briefly. We can not rule out either the computer or the crank sensor at this point however.

Testing the crank sensor with a meter we have an 'ok' reading, however it is impossible to accurately test the sensor without either a scan tool or an oscilloscope. A test meter can give us an idea, but that is it.

When checking the low voltage line on the crank sensor, we would normally want to see a 5V square wave while cranking. That is to say, the line will pulse 5V on for a few milliseconds the 0V off for a few milliseconds, repeating infinitely while cranking.
Using a meter to measure this, we saw mid 1 to 2V readings, which is good to tell us 'something' is happening there and it isn't totally dead, however do to the very slow sampling rate of multimeters we don't know if it is giving a good 5V square wave or if the 1-2V readings are actual readings and not just averages of the 5V due to the sampling speed.

The only further thing you can try on this is to spray some starting fluid in the intake to see if you can keep it running that way. If you can not, you know the crank sensor is most likely at fault as the poor reading will affect your spark timing as well.
If the engine runs fine on starting fluid, then there is a problem with the fuel pump relay driver circuit in the computer... either by bad driver or in rare case the wiring between.


Your best bet from here since you know you do not have power at the pump (so melted connector is out), you know the relay is not energizing properly (while ground is there momentarily, apparently not enough to latch, or you can't tell anyway), and the crank sensor has not been 100% diagnosed, is to get it on a scan tool and check the crank sensor output.
If you see full RPM while cranking (250+), then you will want to go over your checks to make sure you were accurate in your previous checks.... specifically testing for voltage at the pump harness while cranking. If there is voltage and you were incorrect previously, then inspect the module/housing for melting as is very common on these (pump motor will not fix this, you need the whole assembly). If there is no voltage, and the relay is only getting that ground for a brief second, then the computer is at fault. Note that the computer on this model must be replaced with the immobilizer ecu at the same time as they are married permanently, and also the keys must be reprogrammed.

If you do not see proper RPM signal from the crank sensor, and/or you see a P0335 fault, the crank sensor is faulty and requires replacement.
Doug C., ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 6403
Experience: Mitsubishi employed and Factory trained ASE certified technician
Doug C. and other Mitsubishi Specialists are ready to help you
Customer: replied 1 year ago.

Thanks alot for all your help. I am going to try and get a scan tool tomorrow to pull the codes. You have really provided excellent service tonight! My fiance and I really appreciate it!!

Expert:  Doug C. replied 1 year ago.
No problem. Hopefully we find a bad signal from that crank sensor, as things will get expensive quickly if the sensor looks good. However as I mentioned before, if the sensor reading is good, double check your other inspections just to be safe before jumping to any conclusions.... a computer issue is quite expensive on this model, so we want to exhaust our testing first.

If you need further help, just let me know.
Customer: replied 1 year ago.

Doug,


 


I got a code scanner and the only codes that came up where the throttle position sensor and the immobilizer code. po1610. I read on here where you had helped someone else with how to override the immobilizer for a one time start. I noticed this morning that the key is not an original mitsubishi key and was wondering if it possibly could be that its not programmed to the ecu and immobilizer ecu. Would the override procedure work for this vehicle? I checked the glovebox and there is a sticker there with the following number on it


 


A9X248A1


 


Is this the correct number off the sticker?

Expert:  Doug C. replied 1 year ago.
Hi,

The immobilizer will not prevent the fuel pump from running, it will only ground the injector circuit so that the injectors will not operate. If you are certain that the fuel pump is not getting 12V in the crank position, while the immobilizer may be an issue, it is not the reason for the pump not working.

The P1610 certainly is reasonable to expect an incorrect key or that someone tried putting a different computer in the car as this will set a P1610 as well.... and also pretty much make it impossible for you to get the car running without the old computer as well. If you have a flat metal key, then it is a no-brainer on that one. If it has the rubber shield shaped head, just not a Mitsubishi one, it is a transponder key and may or may not be programmed.

If you wanted to try the over ride, your code would be 4188 and you would use the same brake pedal procedure you saw previously.

Worth noting about this, though: If the computer was changed, you will have a mismatch between the computer and immobilizer ecu (setting the P1610)....nothing will make this work other than putting the old computer back or replacing both the computer and immobilizer ecu with new one. If the computer was changed and the immobilizer ecu was replaced with it's matched unit, the serial number on the glove box is no longer valid, as it is tied to the immobilizer ecu. And finally, again the immobilizer system has zero control over the fuel pump, only the injector rail.... so if you are certain the fuel pump is not getting power, this would be an additional problem, not the cause.

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