not sure what i did to fix mpi

[Hesh724]

was driving along up a long smooth hill and car just abruptly shuts off and loses all power. so i pull off, check the fuses and mpi was blown. checked all wires and grounds for fuel pump rewire. pulled ecu and it looked and smelled fine. took off mpi relay to open up and inspect, the bolts were a little loose when i removed it but looked and smelled fine. popped in extra 20a into mpi fuse slot. i regained power until i tried to turn key then it immediately blew again.

so had car towed home. immediately rechecked everything and tightened the mpi bolts down that hold the housing to the dash frame and ecu bolts down better in case vibration caused something. and now the car starts and runs good just after taking it all apart and putting it back together. like fuel pump wiring and inside ecu and mpi all looked good. so it just magically worked after i put it all back together. so if any one has had the same problem let me know what you did just cause im curious.

 

[curt-s]

Possibly a break somewhere in the insulation of importanting wiring. Wouldn't cause a fuse to blow unless it came into contact with any grounded shielding which runs in certain spots (like for the oxygen sensor). With wiring this old, it can be a billion things.

 

[dgdsm]

I can't tell the specifics of your vehicle from your profile, and I don't remember ever experiencing this exact problem, but I believe the MPI relay shares this hard to reach ground that is underneath the radio on the floor with a lot of other components. I suspect any intermittent short anywhere in this circuit could blow that fuse. Maybe the MPI relay itself.

 

[dgdsm]

I once had an intermittent shorts issue in another vehicle that got fixed just by cleaning out the fusebox and contacts with electrical contacts cleaner.