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Electrical & Idle problems with 1985 Rx-7 12A

Old 09-08-15, 04:23 PM
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CA Electrical & Idle problems with 1985 Rx-7 12A

Sorry for lengthy post, but i really appreciate any insight/feedback!

1985 Mazda Rx-7 12A. Was sitting for around 8 years and I dont know any of the history on the car.

I got it to start up so I know it runs. I just went through the car and did a basic tune-up (new battery, spark plugs, wires, oil, oil filter, fuel filter, air filter, fresh gas, new belts, flushed radiator, bleed brake lines and put new master cylinder.

Ive been thinking on changing the cap/rotor and coil next, thoughts? Does this car also have ignitors or are coils the same thing?



Problems:

Wont idle, dies as soon as i let off gas

The RPM gauge works but is sometimes jumpy and doesnt go up smooth. Also the warning buzzer goes off even when its only showing 3000-4000 rpm on the gauge (and it only sounds about that rpm, it dosent sound like its redlining at 7000rpm...but i could be wrong, im new to Rotary engines and how they operate)

I have it jacked up and took rear tires off and shifted through the gears easily getting it to register 50-60MPH on the dash...but rpm stayed around 3-4k and warning buzzer came on at that RPM so I would shift at that point.

MPH and odometer work, but just about all other gauges do not work (temp gauge doesnt work, oil pressure gauge doesnt work, fuel gauge doesnt work)

Battery dash light is on, but very dimly...you can barely make it out during the day. Like its not getting enough voltage or something. (I tested alternator and tests good at 13v+).

EXH dash light is on, lit very dimly as well (exhaust overheating system?)

When the car is off and i turn the key on none of the dashlights light up. Everything remains black until i actually start the car, at which point the battery and Exhs lights come on dimly.

The lights and headbeams work perfect, and the highbeam dash light looks bright and is working. The adjuster to change dimness of the dash panel works fine when the lights are on...but doesnt change the brightness of the Battery/Exs warning lights.

When i put the emergency brake on the Battery/Exhs warning light gets brighter and is easier to make out.

The emergency hazard lights work and lights show up on dash, but neither turn signal work or flash on dash.

The horn doesnt work

Radio turns on and works

The air system works including heat

When I push brake peddle the brake lights dont come on. But when i turn headlights on they light up as normal.

---

I checked the fuse box under the steering wheel to the side of clutch pedal and all fuses are fine.

So what could be going on here? Im guessing multiple problems...or could one bad sensor/gauge/wire be shorting everything out?

Possible bad coil/ignitor the reason why it wont idle? Or just gunked up carb? What about the RPM issue though

Why would battery light be on if alternator is putting out good and the battery is new? Coil/ignitor problem, bad voltage?

Whole dash panel bad and need to be replaced?

Im hoping I can salvage this car and im not getting myself into a real mess! The car is complete and would be a shame to not get it road-worthy again.


Thanks for any advice or input!

I might post take a video so you can hear/see whats going on.

EDIT: Here is a link to the video I just took so you can hear/see what it is doing. There is some sort of buzzing noise coming from the engine/under hood. Maybe just the fanbelt or a vacumn leak maybe? Also you can see how weird the RPM gauge is acting. The video cut off early but basically the warning buzzer for 7000rpm goes off when its showing about 2000-3000rpm on the dash...or sometimes sooner. The rpm gauge isnt really working. Maybe bad ignitors? I was going to switch them but it looks like the only way to take off the inner ignitor is to remove the alternator?

VIDEO: http://sendvid.com/4h1464es

Last edited by The1Sun; 09-08-15 at 09:29 PM.
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Old 09-08-15, 05:13 PM
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i would suggest getting a copy of the FSM first (Foxed.ca). you will likely need to refer to the factory wiring diagrams.

you should absolutely get a new cap and rotor as a part of your tuneup. you shouldn't need to change the coils unless they are bad. the ignitors are actually mounted on the distributor itself and given your tachometer issues, i would suggest taking a closer look at them. the tach signal comes from the trailing ignitor.

for the stalling when you're off the throttle, i would say start simple and check for vacuum leaks. they are easy to occur and can sometimes be hard to locate. after 8 years of sitting, hoses can become brittle and crack prone. it would also be a good idea to clean the carburetor thoroughly. a worst case scenario will have you cleaning the entire fuel system and rebuilding the carburetor. i can understand how daunting it might seem, but if you plan to keep the car, it might best to just get it over with.

for the gauges, i would say start with the associated sensors that feed them. check the connections there and make sure they are clean and secure.

this is sort of an abrupt end, i know, but i will have to continue this later because i have to go right now.
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Old 09-09-15, 10:08 AM
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Originally Posted by diabolical1 View Post
i would suggest getting a copy of the FSM first (Foxed.ca). you will likely need to refer to the factory wiring diagrams.

you should absolutely get a new cap and rotor as a part of your tuneup. you shouldn't need to change the coils unless they are bad. the ignitors are actually mounted on the distributor itself and given your tachometer issues, i would suggest taking a closer look at them. the tach signal comes from the trailing ignitor.

for the stalling when you're off the throttle, i would say start simple and check for vacuum leaks. they are easy to occur and can sometimes be hard to locate. after 8 years of sitting, hoses can become brittle and crack prone. it would also be a good idea to clean the carburetor thoroughly. a worst case scenario will have you cleaning the entire fuel system and rebuilding the carburetor. i can understand how daunting it might seem, but if you plan to keep the car, it might best to just get it over with.

for the gauges, i would say start with the associated sensors that feed them. check the connections there and make sure they are clean and secure.

this is sort of an abrupt end, i know, but i will have to continue this later because i have to go right now.
Great thanks for the info and the links, I'll check them out and see if I can make sense of the wires/hose. I also added a video if that helps
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Old 09-09-15, 08:59 PM
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regarding the noise in the video, maybe start by checking the coasting/shutter valve.
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Old 09-10-15, 06:31 PM
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Originally Posted by diabolical1 View Post
regarding the noise in the video, maybe start by checking the coasting/shutter valve.
Okay ill check into the shutter valve. Thanks

Anyone else have any thoughts? Maybe I should repost this in the 1st Gen thread instead of newbie thread now...
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Old 09-15-15, 04:45 PM
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well, i just happened across your repost in the Gen I forum. i guess i'll close this one now.

https://www.rx7club.com/1st-generati...7-12a-1089484/
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