83 Mazda Rx7

[Brandon.Nutter]

Hello all. I have recently acquired my drivers license. And with that given a car to drive. But as you all know, free things dont come easy. This car was used as a daily driver for a few years, but then my father, Scott Nutter, started racing and just happened to need "spare parts". So long story short, my once daily driver had become a parts car. Over the past several months I've replaced a starter, 2 fuel tanks(one was a 84 tank), a fuel filter, drive shaft, a carb, brake lines, spark plugs, and a few other misc items.
I've come to a problem. The carb. Stock carb idled fine but my father said trying to take it up to 45mph, it died. It had a bad accelerator pump. I switched the accelerator pump. Before i switched the acc. pump, i had to pump the gas a few times to rev it up or it would die. Now the problem is fixed with the acc. pump. But now new problems have arose.
1. Car will NOT idle.
2. Car now has extreme backfiring. (didnt before)
3. When RPMs are held at 5k for 10-20sec, car dies out and stalls.
I myself being new to messing with things of this sort cannot figure out what to do or how to fix this problem. And my father, the Rx7 guru has been out of town and unable to assist me. So i look to the expertise of the IT Forums. Can anyone help? Feel free to email me at [email protected]
Thanks.

[Scott Nutter]

Hey... I resemble that description.

Please, any one, I have a 16 year old with a freshly printed license wanting to cruise in a sweet 83 Rx7. Amazingly parts pulled from plastic bins don't jst bolt together and go. I'm long distance, due to work so any suggestions are greatly appreciated. Things described in a different manner sometimes make it all fit together.

This is a stock car except for a header.

[CRallo]

Way to go kid! That's awesome! You'll love the car :) they really are a treat, it will be worth the work!

I am lucky, I've never had to mess with the carb on mine... So I'm not much help but check out rx7club.com, it is a really good forum!

Good luck!

[BruceG]

Way to go kid! That's awesome! You'll love the car :) they really are a treat, it will be worth the work!

I am lucky, I've never had to mess with the carb on mine... So I'm not much help but check out rx7club.com, it is a really good forum!

Good luck!

Chris...If that kid comes east to LRP, he can watch me go into Big Bend with flames shooting out the exhaust of the #10 12a....awesome...LOL:eclipsee_steering:

[CRallo]

Chris...If that kid comes east to LRP, he can watch me go into Big Bend with flames shooting out the exhaust of the #10 12a....awesome...LOL:eclipsee_steering:

haha, that is awesome! need some pics man! My exhaust is stock so it doesn't shoot much flame but it sure makes some noise some times!


as far as those cars go, let me put it like this: I own a 400+ hp Camaro I've been driving since I was 16 and the bone 85 rx7 GS I paid $300 for is just as much fun to drive!

[ITA_honda]

Hey... I resemble that description.

Please, any one, I have a 16 year old with a freshly printed license wanting to cruise in a sweet 83 Rx7. Amazingly parts pulled from plastic bins don't jst bolt together and go. I'm long distance, due to work so any suggestions are greatly appreciated. Things described in a different manner sometimes make it all fit together.

This is a stock car except for a header.

and im having problems of my own now.
:(

[JLawton]

And NONE of you guys are helping poor Brandon!! :p

[ITA_honda]

And NONE of you guys are helping poor Brandon!! :p


Ive noticed that, but I just had to put my two cents in anyway

[Marcus Miller]

I'm not much help, because Carbs on these cas are the devil :)
Find Sterling & carl on Rx7club, and buy a carb from them....

Make sure your coils, plugs and plugs wires are good and away you go. Does this car still ahve all the smog equipment on it? If so, does it have to? The rats nest is a pain in the butt.

[Spikep]

It sounds like you have a lean condition. Check fuel flow from the electric pump, you may have to jumper the fuel relay, it's under the dash on the right side of the steering column. Check the vacuum hoses for leaks or open ports on the carb. The Nikki carbs are not that hard to work on, NAPA can get the carb kit, and it's not that difficult to clean up and re-gasket. Helps if you have a shop manual but the instructions with the kit are good.
Check the spark plugs, they foul easy, especially if you have flooded it, also make sure you have the plug wires on the correct plug.
I hope this helps.

Spike

[lateapex911]

Check the fuel filter, of course. The old tanks are rust buckets by now, so it's coomon to clog a fuel filter with rust. And if there's no filter, well, a carb teardown/cleaning might be in order. I run a filter right at the entry to the carb, and I use the clear type. Easier to check. There is one stock on the car under the drivers butt, or a bit further back. It's easily ignored.

As mentioned, check the vacuum hoses. They are old, and prone to cracking, stiffening, etc. There are some oddities like the "flapper valve" that can malfunction, but this doens't sound like that's happening.

[tom_sprecher]

Like some have said, rebuilding the carb is not hard, especially if it has been prepped for racing. ;)

[ITA_honda]

Hello all. I have recently acquired my drivers license. And with that given a car to drive. But as you all know, free things dont come easy. This car was used as a daily driver for a few years, but then my father, Scott Nutter, started racing and just happened to need "spare parts". So long story short, my once daily driver had become a parts car. Over the past several months I've replaced a starter, 2 fuel tanks(one was a 84 tank), a fuel filter, drive shaft, a carb, brake lines, spark plugs, and a few other misc items.
I've come to a problem. The carb. Stock carb idled fine but my father said trying to take it up to 45mph, it died. It had a bad accelerator pump. I switched the accelerator pump. Before i switched the acc. pump, i had to pump the gas a few times to rev it up or it would die. Now the problem is fixed with the acc. pump. But now new problems have arose.
1. Car will NOT idle.
2. Car now has extreme backfiring. (didnt before)
3. When RPMs are held at 5k for 10-20sec, car dies out and stalls.
I myself being new to messing with things of this sort cannot figure out what to do or how to fix this problem. And my father, the Rx7 guru has been out of town and unable to assist me. So i look to the expertise of the IT Forums. Can anyone help? Feel free to email me at [email protected]
Thanks.


Brandon - when can we expect you on the track at Nelsons? If you drive as good as your Dad Im going to have to watch my back! :D

[Brandon.Nutter]

Thank you all for the help and ideas. I will try all of them and come back with what results i get.
As for being on the track, that might take as long as it takes to get my car running Haha.

[lateapex911]

Hey, sorry, just reread your first post, I fail for comprehension! I see that you replaced the carb, filter and tanks. I still worry about what's IN the carb, and the vacuum hoses, and of course proper ignition.

[Redshift]

Have you checked the timing? My carb'd 13B did pretty much the same thing when the timing was screwed up.

[dyoungre]

Brandon,
Runs for 5-20 seconds then dies? Can you watch the front float level while you do this procedure with a mirror? With the air cleaner off, hold it at load, and watch 2 things - is there fuel still in the float bowl (1/2 way up the glass), and does the stalling go hand in hand with the secondaries opening?
Do you have a fuel pressure gauge set up at the carb? Again, watch while you hold the RPM up, and make sure it is not dropping off. With stock jets, you want a constant 3 PSI or so.
On the other side, pull off the distributor cap and rotor, steal the ones off your dad's race car, and try it again. Listen for 'ticking' under the distributor cap at idle - if you hear it, it is arcing, and your coils are spending all the energy arcing in the distributor instead of at the spark plug!

[Brandon.Nutter]

Well. I feel quite silly for not catching this one. The problem i described as revving up to 5k and it dieing out, well i only had about 1.5 gal in the tank... So one problem solved.
Now its an idle problem. I have the throttle cable set up so it gives a little gas to it to keep it running at 1k. But i think there is some other solution I'm unaware of. Can anyone help me with this? I think it might have something to do with the screw on the drivers side of the carb? Its a long screw with a metal pin on the end. The fuel mixture screw i believe.
And what nozzles should i block off with the caps? All, or only some? Once again thank you all for the help and input.

[dyoungre]

Here's a link for you:
http://www.sterlingmetalworks.com/Nikki_Carburetor_Manual.pdf

You don't want to use the throttle for idle, if you can get the carb set up for enough air without it. There is an idle circuit that doesn't use the venturi for fuel, and you want it to use that circuit as intended. Vacuum leaks will make life very difficult at idle, as it will make you run very lean. Make sure you don't have any vacuum leaks before trying to adjust your fueling.

One issue - if you have low compression, then you might not be able to keep the engine running at the stock idle speed. At any rate, check ou tthe link on how to adjust the carb. The second thing - spark advance at idle will help make the most of the air/fuel that you have. If you have the vacuum advance (on the primary ignition) disconnected, reconnect.

[Brandon.Nutter]

You don't want to use the throttle for idle, if you can get the carb set up for enough air without it. There is an idle circuit that doesn't use the venturi for fuel, and you want it to use that circuit as intended. Vacuum leaks will make life very difficult at idle, as it will make you run very lean. Make sure you don't have any vacuum leaks before trying to adjust your fueling.

One issue - if you have low compression, then you might not be able to keep the engine running at the stock idle speed. At any rate, check ou tthe link on how to adjust the carb. The second thing - spark advance at idle will help make the most of the air/fuel that you have. If you have the vacuum advance (on the primary ignition) disconnected, reconnect.[/QUOTE]


Everyone has been saying something about a vacuum leak, How do i check for that and what do I check?
How do i check for low compression?
What is spark advance?
Sorry for all the questions, no one here to explain. Reading is just gibberish to me, I prefer to learn by doing/watching.

[dickita15]

An old trick for checking for vacuum leaks is to let the car idle and spray carb cleaner on various lines and connections. When you spray the area with a leak the idle speed will change as the cleaner is sucked in.

[Scott Nutter]

Brandon,
The spark advance is adjusted by rotating the distributor, that is where you loosen the 10mm nut at the base of the distributor. Hook up the timing light to the front leading plug and check the front bottom pulley while twisting the distributor. I believe this has the aftermarket small pulley that I have marked as per the Yaw instructions (years ago). I don't remember what the markings are, I'll try to find the old documentation. It is quite possible that the distibutor is off by one tooth, because I'm sure it has been removed in the past.

[kbailey]

Congrats on the license and the car! I had the pleasure of running with your dad out at Nelson Ledges last year...well I was in the same run group, can't really say I was running with him :)

Anyway my 83 street car had a rusty tank. It got to the point I had to change the filter every 2 months. (The stock filters are really small). As people have already warned you: make sure you have good fuel levels in the bowls even if you have already checked it before.

What is the lowest RPM it will run?

I would start by setting the idle mixture screw to the initial position. Do you have a Mazda manual or Haynes? After that adjust the throttle stop.

There are about 4 miles of vacuum lines in the emissions systems. A small crack can easily mess you up. If you so start replacing them be very, very careful removing them from the plastic solenoids. Those plastic valve bodies are 26 years old and very brittle now. I slit my hoses with a razor before pulling them off and replacing them. (well after I broke half of them I started slitting the hoses).

There are also several big valves on the outside of the carb that work with the air control valve. Checking them is time consuming, but pretty straight forward. I am not a huge fan of the Haynes books, but they are pretty good at describing how to check that whole mess out.

If all the emissions stuff checks out, then check the timing and vacuum advance.

If it still does not work then it could be carb rebuild time. I messed two up before I got it right.

Moron move #1: do not wait for your mom to leave the house and then put the carb body and horn in the dishwasher to clean them! While it cleans them very, very well, the dish washer detergent is corrosive to the aluminum and pits the sealing surfaces.
(okay, hope everyone had a good laugh and no one peed their pants...)

Moron move #2: there are some very small balls inside the carb. I can't remember exactly where, but they are very easy lose when disassembling a dirty old carb. Work on a big clean surface, take pictures and make sure you can find small parts that you drop.

Good Luck!

[tom_sprecher]

IIRC, the balls are in the accelerator pump circuit and act as check valves to make sure gas refills the pump diaphram instead of air.

Unless your state requires emission inspections on older cars (25 yr cutoff here in GA) I'd get rid of all that crap and be done with it.

[Brandon.Nutter]

Well thank you all for the help/ideas. They all helped in my never ending struggle with the 26 year old beast of mine. As of now it runs great. Takes a little bit to warm up and idle, but it does. The only problems now are a missing brake pad clip, the driver rear brake pad clunks up and down when going down the road. And the exhaust is still a bit on the loud side, the neighbors only complain twice a week now...haha just kidding. But again, thank you all for your help and knowledge.