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Need refrence pictures for 81 wiring, vacuum, and ignition?
I just recently bought a 1981 Rx-7 and the wiring, vacuum, and ignition/timing is iffy at best. Ive tried looking at manuals and diagrams but most of them dont include some of the parts im seeing or I cant find them for the 1981. Ill add a few pictures of its engine bay, and if I need to get a better angle let me know and ill take more. The plug wires are flipped for leading/trailing, so thats one of the reasons why im trying to get pictures since its easier to match my car to another car VS a black and white diagram from the early 80s. Its got issues idling and wont start without starting fluid so im not sure if thats vacuum or carburetor or something else entirely. Any pictures or help is appreciated!
I think the disconnected line in this one is cruise control, correct me if im wrong
Good timing! Getting my 81 ready for a Breakfast Club drive tomorrow. Here are some pics; tried to match to the ones you took. Let me know if any particular angle needed.
Is that idle control? I thought it was cruise so I put cruise on it. Where does cruise control go then? Still no clue why my leading and trailing have to be inverted to run right, I don't think vacuum could do that.
Blue is where that line thats supposed to go there goes, and red is where i think it needs to go. Question is then what replaces where that red line goes?
Did some digging and found this. Says it’s for an 83 and I believe that makes it a 12a and the same as a 81. But that’s an educated guess at best. Compare to what you have and see if it matches.
It was the throttle opener, had no vacuum line to it. It idles now! Still trying to find where cruise control vacuum goes, and it still wont start without carb cleaner or starting fluid, but its getting there. Found out my spedometer cable is missing the pin that does into the sensor on the transmission,so there is my lack of spedometer. Drove it home so I can work on it with more tools, now to figure out my tachometer and the leading / trailing swap. Thanks for all the help so far!
For the only starts with cleaner or starter fluid. Two quick kills...
- How is compression? If unknown, do you know the trick for using a cheap standard compression tester to get a quick and dirty idea of how your compression is?
- Once started and running on idle, and you jab the accelerator hard with your foot, does the engine stall or accelerate nicely?
I don't know compression, but jabbing the accelerator with the timing flipped the way it is does just fine. If I swap it to what it should be it stutters bad and feels under powered (tachometer won't work so not sure rpm) but it feels ok when given gas and driving
The jabbing test checks the accelerator pump diaphragm. My 81 had similar 'would start only with starter fluid 'issues, but would also stall if accelerator flooded. Is an easy fix, but sadly not your problem as does not have the stall when accelerator jabbed symptom.
Next, would be good to test compression, since this is a new car to you. Will tell you if your starting and running issues are worn apex seals / damage to inside of housing. And like the accelerator jab, is an easy test. There are compression testers specific for rotary, but you can do a quick and dirty using a standard compression tester. They are under $30 from Harbor Freight. Get one where you can remove the none-return valve, as you will need to remove it from the hose. Once none-return removed from the tester, pull all four spark plug leads and remove one spark plug. Screw in the compression tester to the empty plug hole, then crank the engine using the starter motor for a few seconds filming the compression tester using your phone. Do this on both rotors. The tester should pulse regularly like a heart beat, hopefully 90 psi or above. If the pulsing is irregular eg 90 90 50 90 90 50 90 90 50, or all pulses are under 80 psi then prob looking at engine rebuild. There are some miracle method fluid additive fixes that others may recommend, but have no personal experience with them.
Some potential problems I noticed in your picture, in no particular order;
1) Your Alternator Positive lead is very close to your spark plug leads and could be causing cross-talk, i.e., carrying current from one to the other. If nothing else, you need air gap between them, so route your wires carefully, including each individual spark plug lead (*problem #2l.
2) Spark Plug leads are all over each other. As mentioned above, any time you have high tension wires in contact - even with their silicone insulators - you can get arcing between them, which could be felt as timing off due to spark when you don't want it. Easy fix: add looms or just install them so they dont touch one another.
3) Your Fusible Links, aren't. Someone has just cut wire and spliced on terminator ends to fit where the Fusible Links should be. This will carry far more current under shorted load and will lead to wiring system fires at worst, and overload of these old circuits, at best. Search here for BUS Fuse retrofit for literal plug and play simplicity to replace these with real Fusible Links, which are designed to burn out in the event of a short. You're risking fire...
Thanks for both suggestions! I will do a compression test soon, but could it also be a FPR or a carb base gasket for starting issues? I might be leaking fuel from around the carburetor base since its a bit moist around there. My spark plug wires are pretty bad, I will try to fix them but I still have leading and trailing flipped and I'm hoping to figure that out and maybe my tachometer along with it. The fusible links I was pretty sure were an issue either way, whats a factory equivalent replacement? Something it would have rolled off the assembly line with. I'll try some fixes today when I get home.
These are the fuses I used to replace my OEM fusible links:
Retractor was "Brown" fusible, is now FLF type, 30A (Pink)
Main was "Black" fusible, is now FLF type, 60A (Yellow)
Head was "Brown", is now FLF type, 30 A (Pink)
Ohh, I see how its gotta be now. Im back home so I can finaly look it up and I see pictures of the conversion. Any reason why they used wire type links instead of box fuses originaly? Took it for a drive again today to see if punching it in gear would cause it to stall, and it had no issues at all, felt quick to go (Still looking for an affordable spedometer cale or if I can repair my current one) so I guess that eliminates the accelerator pump diaphragm. I have no clue of the condition of the spark plugs in it if that could be something, was going to change them after I figured out the ignition and timing flip. Could that be why I have no Tachometer? Id like to get that working as soon as possible so I have another but of data I can go by to fix issues (and make shifting at the right time a bit better).
Having been down a similar road, I would do a compression test, even though it’s more likely that your issues are carb, timing or spark wiring issues. It’s such a cheap quick useful test… and good to find out sooner rather than later if you have a compression issue or not. I ended up pulling and rebuilding the engine, then fixed the carb, wiring and timing issues as I reinstalled the engine. Would be a pain to do it the other way around.
Do the easy/cheap tests first. A wise mechanic once told me fault diagnostics are more about working out what it isn’t rather than working out what it is.
Yeah, I will do a compression test soon. How can I test my ignition system? I'm hoping that's why I don't have a tach and that it should be easy enough to fix. I'm also going to do a transmission fluid change soon, so any quick need to knows?
Just had a thought…. If there is an OReillys near you they ‘rent’ compression testers for free. They have loaner tools that you rent by paying for, then refunding when you bring them back. I know they have compression testers but don’t see a timing light on their list, but they are not too expensive, under $50.
By testing ignition system, so you mean timing? And usefully you don’t need the tach to test timing. Hardest part of testing timing is working out if your main pulley is original, then finding the timing marks. Can you post pics of your main pulley?
And just in the theme of quick/cheap methods of ruling stuff out, someone waaaaay more experienced than me mentioned replacing plugs and leads. Do ahead and replace all your leads from coils to distributor and from distributor to plugs. And replace plugs too. Fairly cheap and easy to do, and fingers crossed maybe that’s the fix!
And on transmission fluid, only special tool needed is a pump to reach the fill hole which is high up on top of the tranny. Harborfreight for around $10.
Yeah, I will probably just rent a compression tester. And I want my tach working and I'm thinking my ignition is the solution, so that's what I mean. I have the leading and trailing wires swapped on the motor side of things, upper is swapped with lower, and if I don't have it like that it runs like they are flipped. Not sure why, just runs awful. I'll look for timing marks on the pulley when I get home. I'm thinking this because I believe the tach comes off the trailing coil, so if its messed up could that be why its not working?
If still working on vacuum hose routing…. Just found this under the hood of my car. Staring me in the face! This should be the definitive for vacuum hose routing, since it came from the factory glued to an 81.
09-08-23, 04:08 PM
