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mpi relay extra ground wire

gotbl4d3

Active member
Joined
Feb 28, 2012
Messages
36
Location
billings montana
alright here is the story i got off work drove to the gas station filled up a full tank made it to my friends house and then the car died i started it up and it would only run for about three seconds then die again so i checked my stock pressure regulator my fuel filter and checked that i was getting voltage to my pump and could here my pump running but would only run for about three seconds then my car would run an extra couple seconds then die so i ruled everything out and i found out it was my mpi relay so i swapped that out and its up and running but there is an extra ground wire the orginal owner ghetto rigged into the mpi relay that runs through my firewall and drops down and bolts on to the oil filter housing and it will not run unless i have this ground secured could anybody help me out with this i will put up a pic and show ya what it looks like. and I also did check my ecu while i was removing my relay and i do have leaky cappacitors i got another one on the way but is that would caused it to go out so the guy decided to put another ground off the relay i am so confused with this issue i am having anybody please get back to me and chime in that would be great


here is a pic of the ground wire i am talking about that runs through the firewall and ran down and grounded out to my oil filter housing its pulling it off the pink and white wire
 

DynastyLCD

Well-known member
Joined
May 12, 2006
Messages
761
Location
Harwinton, CT
^x2

why cant you just run that wire to the body, or somewhere closer than the oil filter housing?

if it just needs a ground, i would just ground it to the frame inside the car to un-clutter things.
 

mikus

Well-known member
Joined
Jan 11, 2007
Messages
2,763
Location
Aurora IL
the enter key is your friend

Pin 7 white/red on MPI runs to pin 56 on your ECU where it's also white/red. The ECU grounds pin 56 when car is running, allowing the fuel pump to run.

What you are seeing is one of two things:
- someone was working around an ECU issue (likely) or
- someone wanted the fuel pump to be able to run when the ignition was turned but car not running (dumb, unlikely)

First get your ECU sorted out.

Then, when you get it back, check for continuity between ECU 56 and MPI 7. If they're not connected for some reason, connect them, and undo the ground that's rigged up now. Be sure to SOLDER for a reliable & quality connection, OR, both of those harnesses are easy to de-pin if you want to pull a fresh white/red wire off a donor car. If they are still connected, be sure to tape up where that vamp clamp cut the shielding.
 

gotbl4d3

Active member
Joined
Feb 28, 2012
Messages
36
Location
billings montana
Alright sounds good. Thank you guys so much for all your help it was bothering me so much why the car was running like it should with that stupid extra ground wire still attached thank you guys
 

gotbl4d3

Active member
Joined
Feb 28, 2012
Messages
36
Location
billings montana
Alright, here is my update.

I got the new ecu in I have noticed it does not pull as hard as it used to, but I am not worried about that. The ecu fixed my problem with that extra ground wire i am able to remove and it is still running. But since i got the new ecu in my idle is all over the place and I have idle hunt now every time I am at a stop then goes away after a couple seconds. Could anybody give me any kind of advice to where to start looking to fix this new issue I have with my idle. Thanks it is much appreciated. Oh and I also noticed that the upper honey comb has been removed on the MAS. Thanks guys
 
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