Mitsubishi Montero & Montero Sport This sport utility vehicle offers more size than the other Mitsubishi SUVs, but manages to keep a sporty look and comfortable feel, unlike many larger SUVs.

'91 Montero RS - Bizarre fuel pump issue

Old 01-08-2011, 08:17 PM
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Default '91 Montero RS - Bizarre fuel pump issue

I'm hoping someone can provide some insight into a bizarre [to me at least] fuel-pump problem I am trying to trouble-shoot in a friend's '91 Montero RS. The vehicle has been stored outside for approximately two years and until a few months ago, started on a semi-regular basis. THere was about 1/3 - 1/2 a tank of fuel during this time.

The vehicle is getting no power to the fuel-pump and even when power is put directly to the pump (via the harness connector at the fuel tank) the pump does not seem to run. I have followed all of the trouble-shooting steps Mitchel's lists for both the pump and pump relay. The fusible link at the battery terminal is good. The relay tests correctly and can be heard to shut and open as the key is turned to on or off. As well, I have verified through continuity testing the harness from the fuel-pump relay connector to the tank.

I have also checked the power at the relay connector while it is connected, and pin 3 (Ignition power to the relay) shows 12.6 volts. When I meter pin 2 (relay output power to the pump) it shows about 0.8 volts. In desparation, I removed the relay and jumped pin 3 to pin 2 directly, and still only got 0.8 volts output.

The only conclusion that I can draw from this is that the Engine Control Unit is at fault, but looking at the Mitchel's Schematic this doesn't make a lot of sense (although I will confess that I'm far more a mechanic than a computer guy).

Are there any known fuel-pump or electrical issues with these vehicles? A Google search didn't seem to reveal any.


Last edited by tirediron; 01-08-2011 at 11:21 PM.
Old 01-08-2011, 10:35 PM
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If you can't find any help with this issue here, try the guys on the Wire.

Good Luck
Old 01-08-2011, 11:14 PM
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Will do; thanks!
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