Relay under the air box
 

What the hell does the relay and that thing that looks like an amplifier under the airbox do?

My car idles fine till that relay clicks, then it idles like crap.

Jarrett

If it is in an shinny box it is your fuel pump relay pack. I believe it does this. When your cranking the car it feeds full voltage to the fuel pump. When crusing it drops the voltage to the fuel pump (fuel economy reasons), and when you get on it it then again feeds full voltage to the fuel pump for saftey.

Now why it screws up your car. Dunno.

James

On your turbo car? Just infront of the afm and below?? Fuel pump resistor relay.
https://www.rx7club.com/forum/attach...postid=1451613

Makes the fuel pump run at approx 9 volts at idle and when not under a load. Put the car under a load and the voltage to the fuel pump goes from 9 to 12plus volts(battery voltage). Something like that. Frankley I forget how it works during startup. Whether it has 12v and then after a period goes to nine. I done did forgot. Big ass heat sink with it. See location Ba-22 next jpg
https://www.rx7club.com/forum/attach...postid=1451661

Have you ever counted how many seconds after the engine starts, til the car starts idling crummy?? Do it and let us know please. Maybe fifty seconds?

not even that, maybe 10-20, then the relay clicks, and it changes the idle. If I am idling, and I BARELY tap the gas, it clicks. Hmmm...Strange

I am just trying to figure out why, If I dont rest my foot on the clutch, and rev the motor, it wont idle down. Once I give the clutch pedal a SLIGHT touch, it idles down. Wierd...

Jarrett

Measure the voltage at the fuel pump. It should be ~12V during cranking, ~9V at idle and ~12V under load. Tell us what you're getting. It may be a faulyy relay not letting full voltage through.

Come on, Rat. Admit it.

You just can't drive worth beans.

;)

If It Is clicking like crazy, expect to replace It . Your car won't run with out It functioning correctly.

If you had a 87 like in my schematic, the relay should be pulled in at idle. It appears there is 12v coming from the Main Relay, and what makes the relay come and go is the ground signal from 3D of the ECU. Sooooo if the wire from the ECU was cut, the thing would default to the 12(battery voltage) all the time.

At idle there should be a ground coming from 3D to pull the relay in and put that resistor in the circuit and make the pump put out 9 instead of 12volts.

I'd put a meter on the pump and see what the voltage is at startup and what it is when the relay clicks.

Or you could put a ground on that green/red wire and see if the relay still clicks like it was. If it does, then its the voltage source from the Main Relay that is buggering up things.

But you've probably already done that.

This is kind of screwy. The rail pressure should be the same at idle whether or not it has 12 or volts. That's why they make fprs. YOurs is the stock one, right?

No Waldo fuel pump, right?

You using a turboii boost/pressure sensor? Or something else like one from a n/a.?

And I might add.....darn you have good hearing to hear that relay with the engine running.

EDIT: So that's what a message icon does. Thumb up.:cool:

Here is a series five schematic:http://www.teamfc3s.org/forum/attach...&postid=115249

Pin 1K is the one on a series five that puts a ground on the relay: http://www.teamfc3s.org/forum/attach...&postid=115252

You must have read my 1/4 mile thread...

Jarrett

Its not clicking like crazy, it just clicks when I tap the gas pedal.

Jarrett

No, admittedly, I havent done that yet. Ive been incredibly lazy this weekend. I dont know about the pump. My guess is that its a Walbro, because this car had an FMIC and all the other goodies at one time. As I said before, the car is in good shape, but the chassis wiring harness was attacked by a gang of angry ricers. There is no telling how much damage has been done. I am gonna check the pump voltages today.

Jarrett

I'm just testing, don't pay attention to this. Just wonder if I can put a img here from the other site.
http://www.teamfc3s.org/forum/attach...&postid=115252

Ok, it can be done. Shoulda known.
http://www.teamfc3s.org/forum/attach...&postid=115249

So when we relay the fuel pump aren't we defeating this unit's purpose?

Not if you do it properly, like this.

I did the fuel pump rewire similar to the above thread.......but I got to thinking about it before I did it. I looked at the schematic and said to myself "Self, the real problem here is that the power for the fuel pump is also supplying power to other things, so instead of going to the rear of the car with a big ass wire, let's just do basically what the diagram(in the post above) does, but leave everything up front, new relay and all, but just run the big ass new wire to the right front of the car instead of all the way to the rear of the car. So me, myself and I agreed to do it our way.

You know what. It works just fine that way. Its the other things on the power wire to the pump that drag the voltage down. I.E. the Main Relay and the coil in the Fuel Cut Relay.

All I have said above makes sense to me. May not to anyone else. Bottom line is there is NO sense moving the whole shebang to the rear of the car to get the higher voltage on the fuel pump. In fact its a bloody waste of time and effort.:o: :D :eek:

But that means you're still relying on the factory wiring from the relay/resistor all the way back to the fuel pump. Relocating the relay/resistor to the rear means you can feed the pump direct from the battery with a much thicker and shorter piece of wire, meaning less voltage drop. :)

I like my factory wiring. :p: The removal of the relays makes a big difference in itself. Tomorrow I'll post what my voltage is at 10psi. It's over 12volts by a good margin.:o: Dadgum Wombats from downunder a making me second guess myself :confused:

what if your battery is already back there :D What would be the down side to bi-passing that system? I don't think my old nissan or my talon had anything like that. All just seems like a waste of space and the original owners money

Wombats are from AUSTRALIA! :spank:

Mazda say this system is there to improve fuel economy and pump life. So I guess if you bypass it you'll use more gas and your pump will die sooner. Mazda engineers are more creative than Nisssan and Mitsi ones... :D It's not really all that big...

Ha, I suppose. Know you know why that car stickered for $25,000 back in 88. Aluminum this, aluminum that (not complaining about that part :D ) Rubber boots for the struts, under belly pans, loomed everything with clamp downs ever 6 inches, air duct for the battery....battery cover. Stuff like that.

******Wombats are from AUSTRALIA! *************
In a little known clause in the Treaty of Waitangi , Australia was to become a state/province of NZ (The Maori had a historical claim to Australia). I distinctly remember reading that in world history in high school. Therefore Wombat applies (best I can do on short notice).

:o: :o:

Have no time to check my voltage today, maybe tomorrow. Too busy finding a substitute for Wombats today.

:mad: