MS2Extra and Fuel Pump Mod - '90 MX5

[robd]

Hi All, I'm new to the forums and I'm currently working on building my DIY MS2 V3 kit for my '90 Mazda MX5 which I'm planning to run on GSXR600 ITB's.
I just had a question that I hope someone can help with, for my car year I believe I need to do a fuel pump mod so I have a relay to control my fuel pump, as at the moment the fuel pump is controlled by the AFM and I'll be doing away with that.

I've been reading through this mod here which makes sense(kind of), but my main question is, it says to take power from S12c for the 12V supply but I've already jumpered S12c to JS9 as needed for my MS2 build. Can you jumper two 12v supplies to S12c or do I need to use another 12v supply now instead?

I've built my board based on this guide here but I won't be using an ICV and I'm going for the standalone harness.

Also a few other questions on this, in the text of that FP mod guide it says to use S12c, but then in the pic it has S19 but I can't see that anywhere on the board! Also it says to use R26 which I believe is a 1k resistor, whereas then above it it shows 2.2k!

So yeah I'm slightly confused as to what to do next, or even if there is a better way to control my fuel pump that doesn't involve doing that mod?!

Hope someone can help and apologies if this is in the wrong place or has already been discussed.

P.S. Also any tips on cleaning the board, I've already lightly scraped off the flux but just want to make sure it's clean before I try turning it on!

[dontz125]

P.S. Also any tips on cleaning the board, I've already lightly scraped off the flux but just want to make sure it's clean before I try turning it on!

I can't comment on the other stuff right now, but for board cleaning use 95 or 99% isopropyl alcohol. You do NOT want to use 50 or 70% rubbing alcohol, as they tend to have things like camphor oil - it might help soothe your skin, but you don't want that kind of residue on your electronics!

[SymTech Laboratories]

I just had a question that I hope someone can help with, for my car year I believe I need to do a fuel pump mod so I have a relay to control my fuel pump, as at the moment the fuel pump is controlled by the AFM and I'll be doing away with that.

If you'll be doing away with the AFM and you want a relay to control your fuel pump, you should probably skip this modification altogether.

I've been reading through this mod here which makes sense(kind of), but my main question is, it says to take power from S12c for the 12V supply but I've already jumpered S12c to JS9 as needed for my MS2 build. Can you jumper two 12v supplies to S12c or do I need to use another 12v supply now instead?

You can connect two jumpers to S12C.

Also a few other questions on this, in the text of that FP mod guide it says to use S12c, but then in the pic it has S19 but I can't see that anywhere on the board! Also it says to use R26 which I believe is a 1k resistor, whereas then above it it shows 2.2k!

The numbers in that diagram don't seem to correspond to the parts on a v3.0 board (e.g. D7 isn't a 1N4001 diode either), so you should use a 2.2k ohm resistor.

So yeah I'm slightly confused as to what to do next, or even if there is a better way to control my fuel pump that doesn't involve doing that mod?!

You can easily control your fuel pump using the standard fuel pump driver and a relay. Connect pin #37 on the DB37 connector to one side of the relay's coil, and a switched/fused +12 source to the other side. Connect the relay's COM pin to a switched/fused +12V source and the NO pin to the fuel pump's positive lead. The fuel pump's negative lead should be grounded.

[robd]

Thanks very much for the replys, appreciated.

I still don't fully understand why you'd want to do that mod on the MS board if you can just simply run a wire from pin37 to the standard Fuel Pump relay, doesn't make much sense to me, but I spose it's whatever route you fancy I guess.

I've just been speaking to someone over on an MX5 forum and they've said the same, just run wire from Pin37 of DB37 to the Light Green wire on my standard Fuel Pump relay and that will work.

So I don't think I'll bother with that TIPS125 mod and just run the pin37 to my existing relay.

Here's the other post I was referring too if it's of any help to anyone.
Clicky

Thanks again, I'm sure I'm going to have plenty more questions soon enough!