2G 95 MFI/MPI Relay

[kahl23]

I know a lot of guys are trying to find the MFI/MPI relay, here's where it is and what it looks like on a 95 GSX.

 

[kahl23]

In case you were wondering, that last picture shows the two mounting holes for the relay. They're located behind the center console side panel (passenger's side) below the radio.

Sorry to keep posting but can anyone (i.e. Steve) tell me how to test this baby to see if it works?

 

[freshlane]

ps. I have some 1g MPI/MFI Relays laying around. If anybody needs them let me know. I am cleaning the garage out. (no charge)

 

[steve]

Testing the relay is a matter of applying power to the coil winding and making sure the contacts close. Inside the metal box are two relays, one for the MPI power and one for the fuel pump power. The fuel pump relay has two coil windings and energising either should close the contacts.

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This is the circuit for an 1G automatic car taken from the 1G tech manual. The manual cars have the starter relay and clutch safety switch replacing the AT Inhibitor switch for providing power to the second fuel pump coil to activate the pump while cranking the engine.

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Applying +12v to pin 10 and the ground (-battery) connection to pin 8 should make 12v show up at pins 4 and 5. Same deal for pin 3 and 7 causing 12v to show at pin 2. Applying 12v across pins 9 and 6 will cause continuity between pins 3 and 2. (on relays with the second input)

I haven't looked at the 2G wiring to see if the 95's still use the second input of if they use a different MPI relay. The later 2Gs don't, they use two individual relays.

Steve

 

[luv2rallye]

I haven't looked at the 2G wiring to see if the 9's still use the second input of if they use a different MPI relay. The later 2Gs don't, they use two individual relays.

Steve

I show the 95 still has both relays in the same unit but the FP relay now has only 1 coil (1 input). The 96-99 all have separate relay units.

 

[steve]

Yep, looking more closely at the OP pictures it looks like it's a different relay and connector in the 95 so the pins numbers are likely different too.

Steve


95

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96-99

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[Defiant]

Relays. Camshafts of the electronic world.
We got to the moon and back with those hideous things. I don't know how they managed it.

 

[kahl23]

Haha thanks for all the help guys.

 

[phillabaum03]

im not getting any power to my fuel pump either, took me days to think to see if these cars have fuel pump relays or fuses, im gonna try a friends and see if the car starts!! wish me luck fellas

 

[DSMunknown]

Make sure your pump is working correct as well (or first). I had problems with my pump during on. I hooked up an alternative power source to see if it was activating properly. Turned out that it was seizing up on me. Replaced it with an Evo 8 pump and all was well.

 

[phillabaum03]

thats what i thought at first, swapped them out numerous times now, is there a way to check these?/test

 

[white_dsm]

^

First test:
Have a friend untwist the gas cap and listen inside while you turn the key to the on position, if your friend hears whirling your fuel pump is working. If not go to step 2.

Step two:
Test to see if you're getting voltage at the pump. This can be done under the hood next to the battery. Get a jumper wire from the positive side of the battery onto the fuel pump check terminal. Get your buddy to listen again while you do this, If you still don't hear whirring the fuel pump relay or it's control circuit is faulty.


Step 3:
Check for voltage at the proper pins on the EFI contorl relay, the one in the pic posted above. If voltage is present go to step 4.

Step 4:
Check for voltage at the fuel pump electrical connector, since you done swapped fuel pumps already you should know what the connector looks like. If there's voltage replace the pump, if not there's your problem.

 

[imwigger0303]

ps. I have some 1g MPI/MFI Relays laying around. If anybody needs them let me know. I am cleaning the garage out. (no charge)

hey i could use one if you don't mind

i have like 4 of those relays that have that code on them but different codes for the bottom but none of mine work either i got them with the car when i bought it

 

[BoostedBeaver]

That is the same spot that the 1G MPI is located and it also looks the same.

 

[gcihlar]

Testing the relay is a matter of applying power to the coil winding and making sure the contacts close. Inside the metal box are two relays, one for the MPI power and one for the fuel pump power. The fuel pump relay has two coil windings and energising either should close the contacts.

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In this picture can someone please point to where I need to apply power to?
Thank you very much

 

[steve]

In that picture, nothing. Please read the rest of the post that picture is from. I seem to remember being specific about what pins to use to test.

 

[luv2rallye]

Here: http://www.dsmtuners.com/forums/newbie-forum/263224-mfi-mpi-relay.html#post151211808

 

[steve]

Here: http://www.dsmtuners.com/forums/newbie-forum/263224-mfi-mpi-relay.html#post151211808

You're too nice, I didn't think they needed a link to a post that can scroll back to since it on page 1 of this thread....

 

[NHerron]

Here is what the MPI/MFI relays look like on a '97 GSX.

Same place as the '95, only these are 2 separate relays and are behind that brace there, held on with the 2 bolts seen in the pic.

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The relay with red wires is the MPI relay. That relay brings both pins 12 & 25 up to +12 on the ECU, with key on and the 30A 'moteur' in place. Which is located - fuse box in engine bay. The other is the Fuel Pump relay.

When the MPI relay is activated, the ECU is in turn, activated. Once that happens, the ECU then turns on the OTHER relay next to it for a brief amount of time, which is for the fuel pump to pressurize (prime) the fuel system when the key is first cycled to the 'run' position.

So if you pull the 30A 'moteur' fuse in the engine bay, then neither of those relays will switch on = no fuel pump because = no ECU.

After wiring in a few things and fixing the ECU wiring, I wanted to throw this out there before I forgot

Any false info, please let me know and I'll edit

 

[luv2rallye]

When the MPI relay is activated, the ECU is in turn, activated. Once that happens, the ECU then turns on the OTHER relay next to it, which is for the fuel pump to pressurize (prime) the fuel system when the key is first cycled to the 'run' position.

Any false info, please let me know and I'll edit

YES - false info: The fuel pump relay is only activated by the ECU when the ECU receives CAS pulses (ie. engine is turning). This is true on all 1gs and turbo 2g's. On 1gs there is also activation of the fuel pump by the starter circuit.

Also here's a pic of those 2 relays (on a 96-99) installed and from a different angle: http://www.dsmtuners.com/forums/attachment.php?attachmentid=90631&d=1230882598

 

[NHerron]

Ah-ha! Cool, I did not know that...

 

[954g63gst]

What pins would I check on a 95 GST. I believe my MPI is malfunctioning or my ECU. Its one or the other cause the other relays work and my check engine light doesn't come on when my key is in the on position before I crank it.

 

[JFZERO ECLIPSE]

If the CEL does not pop up and go off after roughly 5 seconds. Check the ECU first, that's where I would put my money.

 

[luv2rallye]

What pins would I check on a 95 GST.

http://www.dsmtuners.com/forums/tun...-power-mpi-mfi-relay-issue.html#post152387614

 

[954g63gst]

https://mail-attachment.googleuserc...278&sads=k1zsEMzVZ3AOodXGzBmHshWIWYQ&sadssc=1

This is my ECU appears good. My fuel pump turns on and my starter clicks but does not spin. I ruled out clutch switch and starter relay and the one by the starter relay. It's the MPI/MFI that clicks after the pump turns on and the starter clicks once.

How do I test the MPI/MFI relay while its plugged in? Sorry I just want to get the problem figured out. The car jump starts. And will continue to idle. But wont start itself.

The battery checks out at 12.6. I've unplugged the clutch switch nothing changed. If I turn the key without pressing the clutch the relay under the radio clicks if I press on the clutch and turn the key the MPI/MFI clicks but the fuel pump turns on and the starter motor gear comes out but doesn't spin.