1983 Mazda RX7 GS - new clutch needed and think fuel pump is going

Spice_Rack

Active Member
Joined
Mar 11, 2007
Messages
188
Location
Boise, Idaho - USA
Car(s)
2004 Nissan 350Z Roadster, 1983 Mazda RX-7 GS
I got an 83 RX7 to play with a few months ago... GS model with 1.1L motor, 144K miles, carburetted... Only paid $800 for it but i'm thinking this may be a waste of money. I don't really have any major plans for the car since I don't have the money. Perhaps I should just sell it since I don't need it, but its kinda fun to drive around and has potential to become a good project car. Anyway it has a few problems and i'd like some advice and what to do about them.

The clutch is slipping badly on 1st gear starts with anything more than 1500 RPM. Also the pedal has been sticking to the floor after a gear change as of recent. I have to pull it back up with my foot, requires a lot of force. I think it's about to go... Anyone ever replace a clutch in these cars? Have any recommendations on what to get and from where? I don't really want to spend more than $250 if I can avoid it... I plan on having my buddy help me out, he has a shop with plenty of tools more than I.

Also the car has this problem with whenever 30% throttle or more is applied in 2nd gear above 5K RPM, 3rd gear above 4k RPM, or 4th gear above 2.5k RPM the car chuggs badly like it wants to stall. Feels like the fuel pump is going out, or at least it isn't getting enough fuel. It is worse the more throttle you give it. The other day it the engine stopped and I had to stop the car and wait about 30 seconds before it would start again. If I short shift into 3rd, 4th, and 5th keeping the RPM's below 3K but at WOT the whole time it does fine. Any thoughts on this? I've been too lazy to check the fuel filter too damn cold, but it looks like i'm going to have to do it anyway. It could also be the carburettor but I know nothing about them and am not that inclined to take it apart. So has anyone experienced this problem or have any ideas here?

I kinda knew the problems were there when I bought it, but they have been getting steadily worse over time. I'm certainly not going to be able to sell it for $800 at this rate unless I fix it. I'm not sure what I want to do at this point... hoping some feedback will help me decide...
 
Clutch is pretty easy and straight-forward to replace. I did it in a driveway with nothing but a couple of jack stands. Before doing that though, your problem sounds more hydraulic. Check to make sure the master and slave cylinder are not leaking, then move from there. If you do end up having to replace the clutch, do everything including the pilot bearing and the release bearing.

Sounds like your nikki carb may need a rebuild. My car is EFI so I've never done it. If it isn't the carb, I would suspect your ignition. Test the plugs first, then move to the leads. It might be a bad ignitor. The RX-7 club is a great source of info for these cars, and you can find shop manuals on that site pretty easily.

My advice: Don't sell the car. They are extremely good cars and very reliable once sorted. I've daily driven my SE for 2 and a half years (through snow, sleet, 100+ degree weather etc) and it hasn't missed a beat.
 
I have a recently rebuilt and hardly used Nikki. Though I'd want a couple hundred bucks for it, and there is a bit of a drive (unless you already plan to go to the meet in Portland).
 
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Clutch is pretty easy and straight-forward to replace. I did it in a driveway with nothing but a couple of jack stands. Before doing that though, your problem sounds more hydraulic. Check to make sure the master and slave cylinder are not leaking, then move from there. If you do end up having to replace the clutch, do everything including the pilot bearing and the release bearing.

Sounds like your nikki carb may need a rebuild. My car is EFI so I've never done it. If it isn't the carb, I would suspect your ignition. Test the plugs first, then move to the leads. It might be a bad ignitor. The RX-7 club is a great source of info for these cars, and you can find shop manuals on that site pretty easily.

My advice: Don't sell the car. They are extremely good cars and very reliable once sorted. I've daily driven my SE for 2 and a half years (through snow, sleet, 100+ degree weather etc) and it hasn't missed a beat.

I'll have to find the slave cylinder... is it easy to get to? The only leaks i've seen are from the oil pan gasket. But wouldn't the clutch slipping issue indicate clutch and not hydralic issue? The clutch feels like crap and has no grip at all, can't even do a burnout on slick water soaked road surfaces. Of course trying wore the clutch even more... but hey. But i'm not saying that there isn't a hydralic problem, I just don't think its my primary issue here. I could be wrong...

I replaced the plugs when I got it, they were pretty nackered. Didn't check the coil and the leads look brand new. I looked at RX7 club forums when I got it but forgot about that... thanks.

I don't really plan on daily driving it, its just a fun car to have on the side. It is incredibly light fun to chuck around. The weight balance is also great, tail always wants to come out and play even though it has an open diff so its hard to get a nice drift going.

No where near as powerful as my Z, but it sure is quick on its feet. The Z feels like an enormous rock sliding and struggling to gain grip on the track compared to the RX7... If I were to do anything to this RX7 though it is to replace the shocks and springs as the ride is way too soft and the car bounces around a lot, pitches and dives during acceleration/braking. Not much roll though, stock sway bars helps out there. Fun car, a little down on power though as someone may have pointed out.


Anyway i'll see if I can find that slave cylinder and check for leaks, but I still know the clutch has to be replaced very soon. I'll check my ignition as well and maybe have a friend look at the carb.

BTW what is your sig from?
 
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I have a recently rebuilt and hardly used Nikki. Though I'd want a couple hundred bucks for it, and there is a bit of a drive (unless you already plan to go to the meet in Portland).

I'll probably pass... unless I were to find out mine is completely hosed. But I don't have spare money sitting around and my cash is probably going towards a clutch kit. Thanks for the offer though.
 
Ok well there are no leaks at the master or slave cylinder. Fluid level was fine. I bled the system and only a little air came out, was done by 4-5 strokes of the clutch pedal. Clutch movement felt good while engine was off, but as soon as I started it I felt the clutch pedal kind of "suck in" a little, in other words got pulled down to the floor more. It was a little hard to get into gear and once I started moving, pushed the clutch to the floor again and the car stalled. So something is definitely wrong here.

I'm not exactly sure what to do except change the clutch and related parts for new.
 
Your pressure plate (aka 'clutch basket') is hosed. New clutch time.
 
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Yeah, if it drops more when it starts then there is a problem that requires taking it apart and you might as well get all new bits.
 
Hmm well from my research the pedal issue points to hydraulics most of the time. A new master and slave is only about $55 so i'm going to replace those as well. Might as well replace the whole system and not have to mess with it any longer.
 
Well.... all done. Took about 14 hours total over 4 days (relaxed mechanic here). Replaced the clutch, pressure plate, release bearing, release cylinder, and master cylinder. Hardest part was the master cylinder actually because it is held in place from inside the cabin up at the clutch pedal. Incredibly tight surroundings and it took me over an hour to get the stupid thing out. It's amazing , all the hours of work to remove part of the exhaust, heat shielding, drive shaft, and transmission out... AND back in, was less stressfull than getting the master cylinder OUT. Ridiculous...

Anyway it is all back together now and feels good, clutch has lots of grip. Only problem I had was once i was done putting it all back together the engine wouldn't start. It would crank but just wouldn't burst to life. I ended up replacing the spark plugs which are only 10 months old with less than 2,000 miles on them. But after replacing the plugs it started right up. Old plugs looked fine though... weird.

Anyway here is a few pics... sorry they suck, my real camera is broken all I have is my crappy mobile phone camera.

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Flywheel has some minor burn marks. I cleaned it up with some rubbing alcohol to get it as much grip as I could.


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Old clutch disc... not nearly as bad as I thought it would be. Probably has another 10-20K miles in it?


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Old pressure plate... same scorch marks as the flywheel but the spring is much weaker, this was probably my problem all along.


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Old vs. new.


So there ya have it... glad I did it, learned a new experience and saved probably about $500. So thanks to everyone for helping me diagnose the problem.
 
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Rotaries can be flooded easy, I bet that is what ruined the plugs.
 
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wow, you're gentle on your clutch! i'm used of seeing those spring completely loose and sometimes even falling out :lol:
(and are that 2 types of springs? haven't seen that before)
 
bone, i'm not gentle on clutches... well I can be, but usually choose to abuse them, when appropriate of course. Anyway i'm thinking maybe the reason it didn't wear so much is the clamping force on pressure plate was weak.


OK, now the starting problem is back. The car ran ok for a day, but every engine start felt like a weak battery. Then last night when I tried to start it, it would not start. Engine turns over slowly, but it won't start... same thing as after I replaced the clutch and tried to start it. So I pulled the alternator and had that tested, came back a pass... So the starter and alternator have been tested and both passed. Everything is hooked up right as far as I can tell, I even bought a new battery and that had no effect. Instrument panel voltmeter reads about 9 to 9.5 volts, even when trying to get jumped and even with the new battery. Engine still slowly tries to turn over but refuses to start. So WHAT is going on here?!?!!??! The only thing I can see wrong is a grounding wire that goes from one of these electric modules to top of the transmission where the lift hook is at is broken and not attached anymore... not sure what these electric modules are but there are 6 of them. Anyway here's a pic for reference:

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I can't imagine it is this grounding lead though preventing start though, but i've been wrong before. Anyway i'm not sure where the problem is but i'd like to get this thing running again instead of collecting dust in my driveway. Anyone have an idea here?
 
sorry double post... was getting 503 service not available errors
 
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I'm guessing a ground for the starter is bad. Trace it and clean it.
 
I'm guessing a ground for the starter is bad. Trace it and clean it.

Could this problem still allow the motor to crank but not start? I'll try this though and let you know... thanks.
 
Check your voltage at, say, the cigarrette lighter with a digital multimeter. Dash voltmeters are notoriously inaccurate.

If you really are running at 9-9.5, you need to (as argatoga mentioned) check and clean your grounds; you should also check and clean both ends of your positive battery cable. Failing that (or while you're at it), check the battery cables for resistance; they are supposed to be replaced after a while and high resistance can be the cause of a lot of idiocy.

Low voltage can cause an engine to crank but not start, especially fuel injected cars. Recent cars include a voltage-sensing circuit protection function that won't let the engine start if the battery drops below 11.7V - but it will still let the starter turn, which confuses people.
 
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His car should be carb'd. Mazda didn't move to fuel injection until '84 or '85.
 
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