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Doug C.
Doug C., ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 6301
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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Mitsubishi eclipse: I am looking for the fuel pump relay..ground

Customer Question

I have a mitsubishi eclipse 2.4 nonturbo I am looking for the fuel pump relay. I am showing a weak ground at the fuel pump. Also the plugs and the injectors are not firing. I discovered they were not firing after I connected a ground to the pump to make it work for test purposes. So the pump works as long as I have the ground connected. the engine still does not start. I have tried another get help site and all I have gotten is loads of useless and incomplete answers. I have been working on cars and trucks all my life. If you have usefull and solid information I would appretiate the help. NO BABBLE PLEASE!!
Submitted: 3 years ago.
Category: Mitsubishi
Expert:  Doug C. replied 3 years ago.
Hi,

You have both a fuel pump relay and a module in this vehicle to be concerned with... the relay powers the module, and the module passing current and ground to the pump.

The fuel pump relay is mounted in the passenger side foot well area, behind the carpet of the center console just below the radio area.... it is attached to the MFI relay as a paired unit.
The relay module is located on exactly the opposite location, in the driver side of the console, again below the radio area mounted behind the carpet. Here is a picture to help a bit:
graphic


My concern at this point would not be so much about the fuel pump not coming on, but that you are not getting injector pulse either.
The fuel pump will only power up if RPM signal is detected in the PCM. Similarly, if there is no RPM signal, your injectors will not fire either. If the fuel pump relay is bad, you will still get injector fire (just nothing will come out); same goes for the module.

I would be focusing on your MFI relay (attached to side of fuel pump relay), the associated fuses, and making sure your crank sensor is working. If the crank sensor goes out, you will have no spark, no fuel, and no injector pulse. Similarly if key power lines are down to the PCM (via fuse or MFI relay failure), there will be no reference voltages, and therefor no spark, no injector fire.
Doug C., ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 6301
Experience: Mitsubishi employed and Factory trained ASE certified technician
Doug C. and other Mitsubishi Specialists are ready to help you
Customer: replied 3 years ago.

I have checked the crank sensor , I have checked the MFI relay. I have not been able to locate a fuse or relay for the ecm. Do you have a way to test the ecm to see if it is getting power.(a wire to check).The crank sensor is sending a signal and I put in a new relay to test the mfi. Still the same problem. Thanks for your help.

Expert:  Doug C. replied 3 years ago.
The best thing to do for that is real simple.... just look at the dash, make sure the Service Engine Soon light is coming. If it isn't, no power. Additionally if your crank sensor is working, the computer is getting power as well as the MFI relay is activating.
Actual computer operation your best bet is to use a scan tool to verify communication and manual operations, if possible.

What did you use to test the crank sensor... oscilloscope, volt meter, scan tool?

Any other information about what happened prior to the vehicle not running?

Are there any other issues known other than no start, no spark, no pulse, no fuel pump?
Customer: replied 3 years ago.
I checked to see if the service engine soon lights up and it does .I checked the crank sensor with a volt meter and a test light I also had a new crank sensor that I put in just to be sure . I used the test light onthe green signal wire while the engine was being turned over, it was sending a pulse. I could not tell what the pulse voltage was because i have a digital volt meter. there are no other issues that I am aware of . The problem started with my wife going to work the road leaving our house is dirt it has been very rough as in if you drive slow it would shake your teeth out if you had some loose. How advanced does the scan tool need to be ,one to receive codes or to watch specific operation.
Expert:  Doug C. replied 3 years ago.
Ideally I would like a full scan tool so we can see if you have any sensors that aren't registering or are out of range.
For now though, if you have a code reader, does it connect/communicate? If so are there any codes?

Have you gone over the fuse boxes and checked for blown fuses yet?
Customer: replied 3 years ago.
I do not have a code reader but I could find one to use to get codes. I have checked and double check both fuse boxes for blown fuses.
Expert:  Doug C. replied 3 years ago.
I would like to see at the least if there is any communication, and if so if there are any codes set.

As I mentioned before the only typical single issue that will drop spark, fuel and pulse is a loss of RPM signal.... excluding fuse/fusible link failures, broken wires etc.
Since we have a pulsing test light on the crank sensor, we can assume at this point the ecm is working.... this wouldn't help if the signal is dirty, however changing out the sensor already should have corrected that if it were the case.

The remaining issues would be a ecm fault... this is not very likely though, and odds are you would be seeing other problems (for starters, no 5V reference on the crank sensor).
For this reason is why I said it would be best to have a full scan tool where you can watch the data lists, see if the ecm is actually seeing the RPM signal or not.... if it is, whether or not it thinks it is activating spark etc.
Customer: replied 3 years ago.
I will try to get a scanner to use . I THANK YOU for your help I will let you know what I find out .Good night and thanks again.
Expert:  Doug C. replied 3 years ago.
No problem at all.... something else that occurred to me.... have you checked belt timing to make sure it is aligned? The reason I ask is we have a few vehicles that the ecm will shut down run operations if there is a cam-crank correlation error (to try to prevent valve collision). I don't *think* this version 2.4l does this, but something to keep in mind.... along the same lines, a cam sensor check for pulse would be in order too.
Of course if there is an issue here, you should see a P0335/P0340 in the system when you scan it, assuming the power hasn't been disconnected and codes lost.

Just something to keep in mind. I will be here tomorrow for half the day if you need help with any checks.
Customer: replied 3 years ago.

Good morning and good news .Last night when you said to check the cam sensor I realized I had been refuring to the cam sensor as the crank sensor. Funny right (not really) so this mourning I looked for the crank sensor and found it ,checked it and it was not sending a signal. So then I took off the timing cover and discovered that the timing belt was coming appart, so I started digging and here lies the problem. A piece of the timing belt bent the plate that triggers the crank sensor and the plate busted the crank sensor. So thanks again I am going to get parts.

Expert:  Doug C. replied 3 years ago.
That's good news!

I was getting a bit concerned as it really did sound like a bad crank sensor. Hopefully belt timing did not jump (sounds like the belt just frayed). Be sure you change both the main belt and the balance shaft belt when replacing.... if you have any questions about the timing or the oil pump alignment, let me know I'd be happy to help.

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