injector and Fuel pump wiring

tibo · Post by **tibo** » Thu Jun 24, 2004 12:31 pm

I am currently having a few troubles/questions with my relay board.

First: For the Fuel Pump, How does the Mega Squirt turn it on? I have no power to the FP terminal on the board with the key in "Off." I can turn the key to get the switched 12+ volts and still not get power to the FP terminal. I get power to everything else though. It sounds like the FP relay is clicking in place, but then againg I do not know which relay is which. I might have heard that it only activates with a tach signal, is this correct?

Second: How are the fuel injectors wired into the board. I am using a GM harness that has each bank of fuel injectors starting out from just two wires (+, -,). But I see 4 spots for injectors 12volts+ and two for inj1 and two for inj2. So how do I wire them?

Thanks for replies.

TT350chevelle · Post by **TT350chevelle** » Thu Jun 24, 2004 9:43 pm

Pin 37 of the MS is grounded when the fuel pump is commanded to run. Did you read the wiring section in the Megamanual?
http://www.megasquirt.info/manual/mtabcon.htm

Brad J.

tibo · Post by **tibo** » Sat Jun 26, 2004 3:42 pm

I have read that and have just re-read it. It still did not answer my question. I found out the fuel pump will come on with a tach signal, by performing different tests on the relay board. I still would like to know how to wire the injectors on the relay board. There are many diagrams of how to wire the injectors to a DB-37 connector, but not to a relay board. Would someone please tell me.

tibo · Post by **tibo** » Sun Jun 27, 2004 10:13 am

Thanks Lance. You cleared it right up. I went out and played with it and got all of the right voltages. Another question for you though, why not go with a GM TPI or aftermarket set up instead of making your own manifold?

Post by **efahl** » Sun Jun 27, 2004 11:35 am

lance wrote:

> When the time comes to add turbochargers to my set-up, I will probably fabricate a manifold, using dual Ford 70mm throttle boddies to take the air from the intercooler to feed each bank of cylinders.

Lance,

Are you some kind of maniac?

I thought the 'Vette was staying NA and
the Honda was getting the turbo. So, you're looking for what, maybe
700 HP from the small block?

Eric

--
Eric Fahlgren http://www.not2fast.com/

Post by **efahl** » Sun Jun 27, 2004 1:36 pm

lance wrote:

> The Vette is NA for now, the Honda will be a test project for my turbo fabrication and tuning skills.

Lance,

Ok, that make sense. I just thought that the turbo in the Honda was
for parity, so it didn't feel like a 98 lb weakling on Muscle Beach.

> maybe a carbon fibre hood and an aluminum block are needed...

Yes, you definitely need an aluminum block and carbon hood. You can tell
your wife I said so. Oh, maybe carbon fenders, too.

> BTW, I'm still working on the MegaTune manual we talked about - I haven't forgotten! I have about 30 pages (w/o illustrations), but it's pretty rough. I'll clean it up and pass something by you in the next week or so.

Excellent, I'll look forward to reading through it.

Thanks,
Eric

--
Eric Fahlgren http://www.not2fast.com/

280zen · Post by **280zen** » Thu Apr 14, 2005 10:17 am

I'm a visual person when it comes to doing things like wiring and such, so I made my own diagram for use with the relay board. Before i start soldering up sensors and injectors I figured I would toss this pic up and see if im correct or once again totally clueless

Jack · Post by **Jack** » Thu Apr 14, 2005 11:38 am

28ozen,

What software are you using to creat/modify that schematic?

Thanks in advance,

Jack

280zen · Post by **280zen** » Thu Apr 14, 2005 11:53 am

just used paintshop pro 5 and copy/pasted the megasquirt diagram.

Jack · Post by **Jack** » Thu Apr 14, 2005 12:59 pm

OK - paint programs. I should have realized that. I should have just asked my kids.

jib

280zen · Post by **280zen** » Thu Apr 14, 2005 1:29 pm

LOL, well, Tis ok to have brain farts now an then! So is the diagram accurate?

Jack · Post by **Jack** » Thu Apr 14, 2005 3:37 pm

The injectors are right. At work I don't have easy access to the rest of it, but the board is labeled. It should be hard to mess up. Then again, I'm just wiring up my first relay board now.

jib

280zen · Post by **280zen** » Fri Apr 15, 2005 4:46 am

Thanks, my only question would have been the injectors and the grounds The rest is easy enough, but I would rather ask then do something really stupid and burn up my car!

Jack · Post by **Jack** » Fri Apr 15, 2005 6:26 am

My only question on your grounds is the TPS ground tied to all of the sensor grounds. I think it's ok, but I'm not certain.

I apologize for not looking all of this up last night. I was in the garage until 11 welding up a car floor <Uggg!> and didn't touch the web or email.

jib

280zen · Post by **280zen** » Fri Apr 15, 2005 7:35 am

The B&G drawing for the relay board says TPS return to pin 14, Air temp return to 17, Coolant Return to 19. The drawing then shows pin 14, 17, 19 all connected in series and running to pin 19 on the DB37. Which really confuses me when it shows all the pins from the relay running to the DB37.

Mephisto · Post by **Mephisto** » Fri Apr 15, 2005 9:06 am

im planning use staged injectors mode, 4 for normal use and more 4 on the hi boost mode, total 8 injectors.

my releay board have se follow plugs

INJECTOR #2
INJECTOR #2
INJECTOR #1
INJECTOR #1

and there is a INJECTOR +12V with 4 pins

How i wire the injectors ? like these ?
INJECTOR #1 - 2 low injectorss
INJECTOR #1 more 2 low flow injectors
INJECTOR #2 - 2 hi flow injectors
INJECTOR #2 more 2 high flow injectors
and the Injector +12V, how i wire it ? i have 4 pins on relay board and 8 injectors

tanx

Mephisto · Post by **Mephisto** » Fri Apr 15, 2005 9:34 am

lance wrote:Mephisto,

INJ1 and INJ2 refer to the drivers for the injectors. In dual table mode (which I assume you will use for staged injection), each VE table controls one of the drivers. So put your 'low flow' injectors on INJ1 (2 injectors on each of the two terminal block connections), and your 'high-flow' injectors on INJ2 (2 injectors on each of the two terminal block connections).

The 12 Volts from the relay board needs to go to each injector, but they all come from the same source, and are all powered whenever the switched source is on, so it doesn't matter much in which order you connect the injectors to the terminal block, just connect two injectors to each.

I think this is what you had in mind, so your thinking looks correct!

Lance.

thanks a lot ! is exactly what i was looking for

i was confused about the +12V 4 pins, so, why 4 pins ? i can use only 1 +12v wire to all injectors too, right ? its obvious, must have some bad thing about this, but i dont know what.