1991 Galant Electrical Problem w/MPI relay

[Floyd Harris]

I'm having a problem with my 1991 Galant, losing electrical power to the fuel pump causing the car to shut off. The MPI Control Relay (located under the glove box) clicks one time turning off the fuel pump which then causes the car to stop running due to lack of fuel. This occurs while stopped at intersections or while driving. I can also drive it for thirty minutes, park it for two hours then it will not run. The relay will only stay on for 3 seconds. Then it has to set for about ten minutes for it to crack. There is no pattern to it. I have replaced the MPI Control Relay, O2 sensor, and MPI Control Unit (the computor) an the car is still doing the same thing. I have the wiring diagram and it shows that the Blk and the Blk-Wht wire is common with the Fuel Pump, O2 Sensor, Ignition Coil, and Distributor.

Update info........ The Diagnostic Trouble Codes are 11, 13, 41, 42. Here's something else that I've discovered. If I take a test light an insert into the back of the wiring harness of the relay on the WHT-RED wire (to MPI Control Relay in the computor) the car will run. I assume that I'm giving the computor the ground signal that it needs to continue the curcuit, but once I remove the test light the fuel pump relay disconnects removing power from the fuel pump (car shuts off). I believe that the reason for my problems is the computor is disconnecting the fuel pump relay due to a missing signal from some related part such as the fuel preesure regulator or fuel injectors. I'm I on the right track?

I'm running out of parts to change out. I'm thinking about using a two pound hammer to repair it...... If you could help me I would greatly appericate it. Thanks and have a good day.... [email protected]

I had a problem with my fuel pump control unit clicking on and off[I take it you mean the large gold-coloured one secured by a couple of bolts vehind the glovebox ?]

I spent £80 on a new one from Mitsubishi, only to find it was actually a powere relay in the box under the bonnet; I had a spare one of these form my previous car, so I dont know how much these are, but I cant see them being too much

I have a 1990 Galant GTi w/4G63 engine, so yours may be slightly different but I hope this helps !

[Floyd Harris]

Thanks Japmetal... I'm not sure what the power relay in the box under the bonnet is. Are you referring to the MPI Control Unit (the computor) which is bolted to the drivers side kick panel?

Originally Posted by Japmetal

I had a problem with my fuel pump control unit clicking on and off[I take it you mean the large gold-coloured one secured by a couple of bolts vehind the glovebox ?]

I spent £80 on a new one from Mitsubishi, only to find it was actually a powere relay in the box under the bonnet; I had a spare one of these form my previous car, so I dont know how much these are, but I cant see them being too much

I have a 1990 Galant GTi w/4G63 engine, so yours may be slightly different but I hope this helps !

[BluFalcon]

Floyd,
Have you had a look at the capacitors in the ECU located in the passenger side kickpanel? There are three capacitors that provide power in the ECU, and they can begin to leak over time. The leaked material can attack the traces on the circuit board, and cause intermittent problems like you've described. Assuming everything else checks out, it wouldn't hurt to pull oth the ECU and crack it open. If it smells burnt or "fishlike" then chances are good that the caps are leaking. It's a simple matter to replace them. Go to: http://www.tmo.com/howto/ecu1g/caps.htm This refers to a 1st gen DSM ECU, but will also apply to your Galant ECU. The capacitor values may be different, but any competent electronics repair shop or elctronic hobbyist can replace these three capacitors for you. Anyway, hope this helps you out.