mixed wiring
04-16-12, 12:39 AM
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mixed wiring
Does anybody know if swapping an 88 engine harness and 87 dash/engine bay harness into an 86 shell would make the car not start? I cant hear the fuel pump prime either when I turn the key to the on position. It seems like only half my harness is actually getting power. Could it be a bad ECU maybe? The heater and AC units that sit under the dash aren't plugged in either. would that make a difference?
04-16-12, 09:46 AM
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The fuel pump doesn't prime.
I can't think of a difference in the engine harness (are you sure you don't mean EMISSIONS HARNESS?) that would cause the car not to start. Heater doesn't matter.
Do you have fuel? Spark?
I can't think of a difference in the engine harness (are you sure you don't mean EMISSIONS HARNESS?) that would cause the car not to start. Heater doesn't matter.
Do you have fuel? Spark?
04-19-12, 02:35 PM
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there's fuel in the tank, and yes i have spark. would it not try to prime if there's no fuel? the harness that runs from the ECU, through the firewall and to the injectors and stuff on the engine. is that the emissions harness? in theory, everything i swapped over should work right? i got the 87 a few years back. it was running, but needed a tune up which wasn't too hard. the dude gave me an 88 parts car with it for free. had an engine/auto tranny and everything, just wasn't running. the 87 had been put into a wall on the drivers side so the main cross member was bent and the engine wall was cocked in a little. so i started cutting the front apart on both cars so i could put the good cross member from the 88 in the 87. everything was almost ready to be welded in, then my buddy calls me and says "hey dude, there's an 86 shell in sunnyside. lets go look at it cuz i don't wanna weld the thing". i was like, okay, i dont wanna finish cutting it, so we ended up going and getting the car. turns out, the dumbass who pulled the engine just cut the wiring harness instead of disconnecting it from the engine or ECU. so i cut my harness and spliced the two together. they matched up perfectly too, but the car wouldn't start. no fuel pump, no starter. so i pulled the harness out of the 88 and put it in the 86. still nothing. so i pulled the 20 foot long harness out from under the dash of the 87, fed it through the firewall, disconnected it from the engine bay, and plugged it into the 86 thinking that might be the problem. now im just stuck. i dont know whats wrong. its gotta be wiring. the little unit that sits on the engine behind the throttle body was making noise though. like some strange ticking sound i never heard before. could that maybe have something to do with it?
04-20-12, 09:41 AM
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Are you getting fuel to the injectors?
The fuel pump only runs while you are cranking the car and while the AFM detects airflow. There is no "prime".
The harness that runs to the ECU is the emissions harness.
Oh, you spliced the harness....well, you 're going to have to use a meter and check EVERY pin on the ECU to the appropriate pin on the harness and connector. There were some colour changes between years.
The fuel pump only runs while you are cranking the car and while the AFM detects airflow. There is no "prime".
The harness that runs to the ECU is the emissions harness.
Oh, you spliced the harness....well, you 're going to have to use a meter and check EVERY pin on the ECU to the appropriate pin on the harness and connector. There were some colour changes between years.
04-20-12, 12:48 PM
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u know how u can hear the fuel pump in the back when u turn the key to the "on" position but don't crank it yet? yea, I'm not hearing it. the emissions harness that's in it now is out of the 88 which had an auto tranny but that shouldn't matter right?
04-20-12, 02:25 PM
#6
If you run a jumper wire to connect the two sides of the fuel check connector (yellow two prong plug on passenger side by the strut tower) the fuel pump should run continuously when you turn the key to on. If not jumpered, normal operation, the the pump only comes on when the engine is drawing air and needing fuel. The 88 harness did have some differences from the 86-87 harness. The best bet is to get the factory wiring diagram on SgtFox's website and start tracing what goes where. I assume the 86 car and the 87 engine are both naturally aspirated? The turbo cars used a different ECU and I believe the NA 88 had a different ECU as well, I'm not sure on that last though, as I have the 87 NA. Yeah, cutting the harness was a bad deal. It's a long tedious process to trace down all the wires and pins.
04-20-12, 06:47 PM
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Take your fuel pump out. IF its been sitting for a while... Check to see if the in tank rubber hose has corroded or if the sock is rusty... ect.... start at the fuel tank and work your way back.
use a multimeter and a buddy to check for power at the plug during cranking.
use a multimeter and a buddy to check for power at the plug during cranking.
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04-21-12, 12:24 AM
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the fuel pump is fine. i used the one from the 87 which was running and has a brand new strainer on it. idk if its getting power though. theres no power at my ignition switch anymore either. everything on the harness plugs in to where it should go, theres just a couple extra connectors cuz the car had power windows and stuff
04-21-12, 08:11 AM
#9
If you had power at the ignition switch at one time but presently you do not then check the Main fuse. Then if that is okay check the outbound Black wire from the engine fuse box (wire comes from the side of the fuse box closest to the windshield. This Black wire drops below the fuse box and plugs into another wire via a Black connector a foot or so below the fuse box, and this wire then runs to the ignition switch to power it up.
04-21-12, 12:34 PM
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THE FUEL PUMP ONLY RUNS WHILE YOU ARE CRANKING THE CAR OR WHILE THE ENGINE IS RUNNING.
As others mentioned you can jump the yellow test connector to cause the fuel pump to run anytime the key is on IGN.
If there is no power at your ignition switch, then you need to backtrack with a voltmeter through the wiring until you do find power. Then figure out what's wrong.
01-15-13, 02:23 PM
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New problem. My cluster and heater are not working. Is there a main relay somewhere? Also, when I turn the key to ign., I hear a single click (sounds like a relay) coming from somewhere under the hood. Is that normal?
01-15-13, 11:30 PM
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Similar Issues
Thanks for the information, I am having simliar issues with my recent S4 13B T swap in my S4 vert. Except I have a white ecu connector next to the yellow and green receiving connectors on the passenger kick panel, that I have not connected yet. I am unsure where to connect it. My motor cranks but will not start and my dash and gauge cluster do not light up. I will plug it in and see if that makes a difference. I also need to wire the alternator to the ignition and dash, I am sure (hoping) that those unfinished steps once complete my car will fire up.
04-08-13, 09:16 AM
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Next problem. I got the gauge cluster working. There were 3 fuses that were blown. The blower motor for the heat/AC doesn't work though. The thick blue wire with the white stripe that goes to the plug on the motor is supposed to be the power wire right? Also, the 7.5 amp fuse marked "room" in the block to the left of my clutch pedal keeps blowing. I even threw a 10 amp in there to see and it blew too. So it must have way too much amperage going through it then right? Why could that be? What does "room" mean anyway? I just recently went through my whole brake setup as well. The pedal is fine, the booster I "think" is fine (seems to be functioning alright), the master cylinder is new, the lines are bled, the calipers and brackets that mount them to the car are sliding on each other fine, the caliper pistons themselves are moving fine, the pads are cheap Duralast brand, but new, the only thing that isn't legitimate is the springs that go between the pads. I only have 1 out the 4 that should be there. Anyway, I am hearing the rotors rub as I'm rolling down the street in neutral like the pads are still touching the rotors after I let off the brakes. Are the springs really strong enough to push the pads back apart so they don't rub? In other words, are they really a necessity? Could it maybe even be something else and not the springs? Thanks =)
04-08-13, 09:41 AM
#20
Room fuse powers: Clock, stereo, interior lights, alarm, ECU. The wire is Blue/Red. Apparently this wire is shorting out so you'll have to locate this troublesome spot. And you should not place a larger amp fuse in place of a smaller rated one.
Fan related info. Take heed to what Hailer's suggests.
https://www.rx7club.com/2nd-generati...arched-584424/
Fan related info. Take heed to what Hailer's suggests.
https://www.rx7club.com/2nd-generati...arched-584424/
Last edited by satch; 04-08-13 at 09:43 AM.
04-08-13, 07:27 PM
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[QUOTE= The pedal is fine, the booster I "think" is fine (seems to be functioning alright), the master cylinder is new, the lines are bled, the calipers and brackets that mount them to the car are sliding on each other fine, the caliper pistons themselves are moving fine, the pads are cheap Duralast brand, but new, the only thing that isn't legitimate is the springs that go between the pads. I only have 1 out the 4 that should be there. Anyway, I am hearing the rotors rub as I'm rolling down the street in neutral like the pads are still touching the rotors after I let off the brakes. Are the springs really strong enough to push the pads back apart so they don't rub? In other words, are they really a necessity? Could it maybe even be something else and not the springs? Thanks =)[/QUOTE]
This is one area I do know in general to all automobiles. There is residual break pressure in all break systems that take up slack so brake pads and shoes do not have to travel far (eliminates brake pad/shoe travel delay when the pedal is pushed) so your pads will have slight contact, especially when new pads, or shoes are installed. The shims on your brake pads have nothing to do with the pads being in contact with the rotor, and should always be used to absorb the pressure and contact from the caliper piston. If your calipers are old and worn (piston seals), more than likely it's time to rebuild the caliper, or replace them. Also be sure to apply some contact grease on the caliper pins as your RX7 has floating calipers that slide back and forth during break application and release. When the pin is dry the caliper can get stuck, or bind. And one last note, be sure to use the glue for the brake pad shims, that keeps the pads in contact with the caliper piston so they do not sit inside the caliper loose and rattle.
This is one area I do know in general to all automobiles. There is residual break pressure in all break systems that take up slack so brake pads and shoes do not have to travel far (eliminates brake pad/shoe travel delay when the pedal is pushed) so your pads will have slight contact, especially when new pads, or shoes are installed. The shims on your brake pads have nothing to do with the pads being in contact with the rotor, and should always be used to absorb the pressure and contact from the caliper piston. If your calipers are old and worn (piston seals), more than likely it's time to rebuild the caliper, or replace them. Also be sure to apply some contact grease on the caliper pins as your RX7 has floating calipers that slide back and forth during break application and release. When the pin is dry the caliper can get stuck, or bind. And one last note, be sure to use the glue for the brake pad shims, that keeps the pads in contact with the caliper piston so they do not sit inside the caliper loose and rattle.
04-09-13, 09:27 AM
#24
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Hahaha! Thanks misterstyx69. Okay, so I have no glue on the pads/caliper pistons, but two of the four little metal clips inside each caliper that hold the pads in place have a bend in them from the factory that keeps pressure on the pads and holds them in place. In other words, there inst any rattling. I've never heard of using glue though. Is it still necessary you think? If so, what should I get? Oh, and all the calipers on the car are single piston. Not the 4 piston ones. Would I still need the little springs then if I use glue? I greased all the pins a few days ago. =)
