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Discussion Starter · #1 · (Edited)
My car started having issues a while ago where there would be a loud buzzing sound from the MFI when I would try to start it, but it would start eventually. The other day, it wouldn't start at all and the MFI would just keep buzzing. I replaced it today but the car still won't start and just keeps buzzing. Alternator, battery, starter, and ignition switch were all replaced within the current year. Is the only possible way to fix this with the fuel pump relay bypass?
 

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93 NA ATX 3000gt DOHC
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You didn’t give car details but looking back at some of your earlier post, I assume your talking about 1998 SOHC engine car. If so you don’t have a fuel pump relay to bypass, they’re only found on TT engines.

MFI buzzing indicates it’s either not getting full power to control circuit or a bad ground. Since ground is controlled by ECU that are not known to have internal problems on a 98 model year car, I’d concentrate on low power to MFI control circuit.

I don’t have prints available to me of 98 base SOHC cars, so the following may not be completely correct as I can only use component id’s from 94 model year SOHC prints.

First, you should pull the 20amp #1 Dedicated Fuse located in relay box under hood near air filter box (possible labeled ECI on cover), check socket retaining clips for not being spread open enough to cause poor connection to fuse legs. You can use a small screw driver to pry them gently closer together, closing the gap between them and making a tighter contact to fuse legs when its reinserted. But if you didn’t remove battery cable before doing this, be careful as one side of the clips have constant battery power.
Click on image to enlarge

Next, do same thing with 15amp #12 fuse in under dash fuse box. Not sure if below picture is same as your 98 fuse box.

Lets us know if this helped your situation or not.
 

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Discussion Starter · #3 ·
You didn’t give car details but looking back at some of your earlier post, I assume your talking about 1998 SOHC engine car. If so you don’t have a fuel pump relay to bypass, they’re only found on TT engines.

MFI buzzing indicates it’s either not getting full power to control circuit or a bad ground. Since ground is controlled by ECU that are not known to have internal problems on a 98 model year car, I’d concentrate on low power to MFI control circuit.

I don’t have prints available to me of 98 base SOHC cars, so the following may not be completely correct as I can only use component id’s from 94 model year SOHC prints.

First, you should pull the 20amp #1 Dedicated Fuse located in relay box under hood near air filter box (possible labeled ECI on cover), check socket retaining clips for not being spread open enough to cause poor connection to fuse legs. You can use a small screw driver to pry them gently closer together, closing the gap between them and making a tighter contact to fuse legs when its reinserted. But if you didn’t remove battery cable before doing this, be careful as one side of the clips have constant battery power.
View attachment 298320 Click on image to enlarge

Next, do same thing with 15amp #12 fuse in under dash fuse box. Not sure if below picture is same as your 98 fuse box.
View attachment 298321
Lets us know if this helped your situation or not.
Gotcha, I am going to check tomorrow morning. If one of the fuses is blown however, simply replacing it won't fix the core issue right? It could burn out again?
 

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93 NA ATX 3000gt DOHC
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Gotcha, I am going to check tomorrow morning. If one of the fuses is blown however, simply replacing it won't fix the core issue right? It could burn out again?
If either was blown, the MFI won’t even buzz. But yes if clips not tight to fuse legs, simply replacing fuse wouldn’t cure problem and the heat generated at connection point could cause fuse to eventually burn out.
 

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Discussion Starter · #5 ·
If either was blown, the MFI won’t even buzz. But yes if clips not tight to fuse legs, simply replacing fuse wouldn’t cure problem and the heat generated at connection point could cause fuse to eventually burn out.
If neither fuses are blown, what could be the next possible cause? Because after I replaced it with a new MFI relay, it just kept buzzing.
 

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If neither fuses are blown, what could be the next possible cause? Because after I replaced it with a new MFI relay, it just kept buzzing.
Next step would be to take voltage reading at MFI relay on Red wire with black stripe and Black wire with white stripe with ignition switch ON, to confirm full battery voltage is getting thru wires and connectors to the MFI relay.

If that test good then it would be looking for a bad ground point somewhere, but wouldn’t open that bucket of worms until full voltage is confirmed at relay.
 

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Discussion Starter · #7 ·
Next step would be to take voltage reading at MFI relay on Red wire with black stripe and Black wire with white stripe with ignition switch ON, to confirm full battery voltage is getting thru wires and connectors to the MFI relay.

If that test good then it would be looking for a bad ground point somewhere, but wouldn’t open that bucket of worms until full voltage is confirmed at relay.
Welp, I checked the fuses today and they were all intact. The car ended up starting today even though I didn't do anything at all to it after switching the relays.
 
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