1G 1st gen MFI relay problems

[92ViperRedGST]

Ok, its all pretty simple you would think. I have 92 GST that I am losing the fuel pump and pressure after car runs for about three seconds after start. I hear the MFI relay click then fuel pressure drops and car dies.

I have gotten a new MFI relay and tried that but car stills continues to die after a few seconds. I have opened the MFI relay and watched the circuit open back up after a few seconds but I can close circuit and it will keep the fuel pump on and it will stay running but with a horrible miss. Problem started out of no where and there where no indication of error or problem before starting the car and finding problem the other day.

I need help here I am completely stumped.. Has anyone scene this before?

 

[yokotabrat]

Check your ECU for cap leakage. The fuel pump portion of the MPI relay is controlled by the starter and the ECU. The starter portion turns the MPI relay on when you first start the car. The ECU is then supposed to take control and keep the MPI relay active, but when the top electrolytic capacitor fails, it tends to take out the trace that control the relay.

 

[92ViperRedGST]

Ok im not real hip on dsm yet so im not sure what cap is. I have not figured out how to communicate my snap on verus scanner with my car... lack of a certain hyun-2 plugin.... I can get ahold of another fwd 92 turbo ecu to try... what do you think>?

 

[LiquidX]

Cap is short for capacitor. When they get old, they start to break down and leak onto the circuit board causing problems and possible shorts which is not good. You can open it up and I think the 1g ECU is under the hood and look for off colors on the board; browns, off greens, bubbling etc.

 

[yokotabrat]

Check out this site for information on the capacitors in the ECU and what they look like.

89-94 Capacitor Replacement

The ECU is in the center console behind the radio. If you have access to another known good 92 ECU, that would be a good way to check if it's the ECU.

 

[nightracer91]

I would swap ECU's and see what happens...

 

[LiquidX]

Check out this site for information on the capacitors in the ecu and what they look like.

89-94 Capacitor Replacement

The ecu is in the center console behind the radio. If you have access to another known good 92 ecu, that would be a good way to check if it's the ecu.

I know the 2g ECU is behind the radio, I heard the 1g ECU was under the hood. Was my info incorrect?

 

[yokotabrat]

I know the 2g ECU is behind the radio, I heard the 1g ECU was under the hood. Was my info incorrect?

Yes, that's incorrect. 1g ECUs are behind the radio as well.

 

[talontsi4g63t]

hi guys hows it going I have a problem with my 90 Talon TSi. I got the car couple days ago and it would not start. I got the car to start by switching my cam sensors with my other Talon I had and it fired right up but the problem is that it wouldn't stay running. I have to keep playing the throttle to keep it from dieing and every time I let of the gas the boost gauge goes to -7 vacuum and when I floor the gas the throttle bumps up to 2k and drops to 600 stays for a second and dies.

I'm not sure ### to look at next checked ECU it's still good getting spark and fuel compression is perfect some one please help.

thanx in advance

 

[92ViperRedGST]

i need a diagram of my ecu... opened mine up and found one of the six little black rectangles on the right burned up... therefore burning part of my board.... what are those????

 

[yokotabrat]

They are drivers used to control various solenoids. Check out this site to help you figure out which driver is blown:

http://www.dsmtuners.com/forums/art...585-troubleshooting-fried-ecu-components.html

If the right most one is blown, that's probably why your car doesn't keep the fuel pump on.

 

[92ViperRedGST]

Just wanted to thank all the fellow DSM'rs who helped me figure out my car. It turned out to be burnt fuel pump driver in the ECU. I bought an ECU from someone who said it ran, put it in and no dice, car had fuel pump but no spark. I opened the ECU and all three caps leaked on main board. Then I cleaned and replaced caps and car started and ran good but just so happens I was at a jobsite by a salvage yard the other day and thought to ask them about an ECU for my GST. They then told me they had a rebuilt one for 60 bux, so I picked it up.

ANYWAYS THANKS TO YOKOBRAT AND ALL THE OTHERS ON THE TECH INFO.... ANYONE NEED A 1G FWD TURBO ECU LET ME KNOW!!!!

 

[yokotabrat]

No problem. Glad you got it all worked out.