1mouse3

my brother got this 87 rx7 13b na with a rebuilt motor early last year. first we are back to having a issue with the fuel pump relay, he dont remember how he riged it at first. he had a switch for the pump an had a jumper that sometimes had to be remove to get it to start if it got to cold. to start it the pump had to be turn on for 2sec then shut off till it starts up, if left on it flud the motor. the relay decied to work for the past year but he'd pull it to start. it is timmed at about 30* to keep from having the header turn cheery red, it seems a bit ritch but if I pull the distubutor an drop it a tooth over it is at about 18*. that is lean an will have a red header, how it is set right now it wont idel an pules from 1400 to 2100 at no throttle(sometimes idels a 2000). plus a lot of stuff got striped of the motor, I am wondering what would be a good place to start with this

misterstyx69

iTrader: (142)

Your first concern would be to Time the engine to make sure that it is Correct.
The way it sounds is that someone rigged a fuel cut switch in it.That would be to deal with Leaky injectors.Your header glowing is saying that it is dumping fuel.
You also need to Compression test the engine to make sure that the engine is healthy.

1mouse3

what made me think it was lean was plugs would be grey when at factor timming but would have glowing header. at a tooth off an at about 30* it runs better till the plugs foul out from to much fuel. so I am wanting to pull the an replace the injectors, then reset the timming back to factor. is there a way around not have to get that $100 realy, like with a common relay. it dose not seem to low on compression, there is a hole lot of exhaust pressure

misterstyx69

iTrader: (142)

You can half *** fix it or fix it right.
which do you prefer?
COMP Check:Rotary Resurrection home of the budget rebuild.
Injector cleaning: WitchHunter Performance - Injector Cleaning & Flow Testing Services

1mouse3

thank for the links, I will see if he gots spare injectors for it an have them sent off. I will also run a comp test even though it sounds like a strong jet prop that sets off every alarm in said airea. what I am finding out about the fuel relay is, it gives wot 12v triggered by afm and a resistor that serves as a 9v bypass. if that is how it works I can use a ballast resistor as a 9v bypass an a standard bosch relay triggered by afm for 12v at wot. I have a bunch of them resistors an relays laying aroud, that would keep from having a failure prone relay that will over heat an burn out.

Aaron Cake

iTrader: (1)

Have you looked at all at the Haynes/FSM for timing and wiring diagrams?

The Factory Service Manuals for all years of RX-7 (and many other rotary cars) can be downloaded for free here: Foxed.ca - Mazda RX-7 Manuals . They contain all common service information information and more, and are an essential tool for any sort of service work that needs to be performed on these cars.

Additionally, the Haynes service manual for the 1986 thru 1991 RX-7 (both turbo and NA) can be found at most local auto parts stores or purchased from any good bookstore (ISBN number 1 56392 007 7). It is only about $25 and is a great quick reference for things like this. Not only does it contain most of the information in the FSM condensed into an easy to read format, but it includes full wiring diagrams as well.

These manuals will answer 99% of service related questions for the car and if you intend to do your own repair work, you will need at least one of them. Preferably both, since the FSM is a free download. The Haynes is a good quick reference covering 99% of questions, while the FSMs show complete and detailed procedures.

satch

iTrader: (1)

If you are referring to the fuel relay in the engine compartment then it can simply be bypassed for good or until you find a replacement. Jumpering the Blue/Red wires to the Blue/Green wires in the unplugged relay plug does the trick.

1mouse3

I got a haynes manual but it dont get into enough detal on stuff. the relay I am refering to is the one that was bolted to the column once apon a time, its black with a yellow plug and looks like the one used on fords. I know how to set the timing right, you set yellow line to pin then aline the mark on cas. but I had to move it one tooth from that to get it timed so it runs right, whitch is 25-30* and that dont seem right to have to set it that far off. almost every thing got deleted off the motor like the acuators, egr, oil/fuel mixer (2 stroke in gas is need), ect. it has a header with 3" back to a fart can an a bs electric fan that wont keep the motor cool.

satch

iTrader: (1)

The relay you are then referring to is the Circuit Opening Relay. W/key to start the top row far left wire, being B/W, should have at least 9 volts. If it does then the Blue/Red wire in the plug should have that voltage as well and this voltage then powers the fuel pump. There is a second coil within this relay that is specifically for the car to operate once the rpm rises to 500 or above. This second coil receives a ground from the AFM as a fuel switch within the AFM controls whether or not a ground signal is sent to the coil via the Brown wire in the plug. If the ground is there then the coil receives voltage from the B/W wire in the top row center position as powered by the 15 amp Engine fuse. If these two elements function as they should then the Blue wire powering the pump should have voltage. If the fuel switch in the AFM is faulty then it could cause the second relay coil to not have the necessary ground thus no power to the pump once the rpm reaches 500 or higher. A jumper could be placed in one of two spots. Either at the Fuel Check Connector or at the relay itself. This would be achieved by jumpering the Brown wire to the solid Black wire (constant ground) found in the bottom row far left position in the Yellow/Black relay.

1mouse3

thanks for the explanation, that means the afm is malfunctioning or the co relay is overheating. at wot the fuel pump will cut out with the relay in place. I did that comp check an it was good. I also hooked up a pressure gauge in the fule line, I got about 33 at idle an 39 with it off. it held pressure for a bit, so I would think the injectors are not leaking. so what else could cause it to run rich

1mouse3

just thought of somthing else, it has a 90 intake but I dont remeber what year injectors its got. would that cause an issue, the po throw ever mod/hack under the sun at it. is there anything I should pay attention to that it is done right

satch

iTrader: (1)

Early injectors were low impedance while later models were high impedance. Switch was made in the middle of 87. Low impedance injectors would have the resistor box while the high impedance model would not. Looking for the box near the passenger fender or taking the ohm reading of the secondary injectors could tell the story. Low have 2-3 ohms and high have close to 12 ohms.

1mouse3

it has the high impedance injectors and the resistor box box has been deleted. it has a 87 lower, 90 upper and 87 throttle body I belive

1mouse3

one thing that has happened twice but went away, is the leading an trailing plugs would fire at the same time. first time we put used controlers in, second time we put a used ecu in. it has msd coils that were new when got the car and they check out. would it be a good idle to put the actuators back in the intake, if so what all would be needed to operate them. the po gave us new aftermarket ones, and would it hurt high rpm power. would ether of cause the timming to have to be so far off, or the glowing exhaust