smile444

Umm,

My Rex is experiencing all of these problems:

- lurches at times [MAJOR LURCHING],
- stalls when stopping at stoplights,
- stalls when starting at stoplights [1st gear].
- stalls when turning corners quickly,
- backfires so bad that it feels like someone is kicking the back of my seat, scares other drivers
- backfires often
- sputters terribly for intermittent periods [sputtering = loss of power, stalling, lurching, no acceleration]
- experiences power loss and decelleration on the highway at high speeds, slowing down slower than 30 mph,
- bogs down if I floor it
- multiple backfires on decelleration,
- engine is loud (makes me think there could be a hole somewhere under that heat shield?)

Her are its current exhaust components:

- stock exhaust manifold with heat shield,
- catalytic converters have been removed,
- replacement muffler not blown up yet,
- air pump has been removed.

Please help. I am looking and learning all I can. It may be running rich or lean? Are there more emissions devices that I need to remove/plug/disconnect?

Ack!

Joe in KC

damon

sound like it is running rich and your timing is off, or a really bad vaccume leak

is your fuel system all stock? Have you done any modifications to the car/emmisions? since you have removed the cats I assume you no longer have a rats nest (if you do, do a search for rats nest removal). You may want to get a header for your car since you are going that route. On the carb there are two windows , you want to get in there and see that they are showing fuel up to the halfway point on the glass, if not post a reply and let us know what it is doing and we can help further. also if you do not have a fuel pressure regulator (not the cheap dial type from auto zone) you may want to get one.

peace

jeremy

iTrader: (1)

or all three. have you done a tune up: cap, rotor, plugs, wires? make sure you are getting a good spark. then move to fuel. if you are running rich and have a holed exhaust you will get backfires out the wazoo. backfires when letting off the gas are a normal occurence with a rotary, especially the 1st gens. checking timing should be pretty simple and straight forward.

racermike

Definantly sounds rich. May have a stuck float. Check the overflow inside the carb. You say "engine" sounds loud but do you really think it is the exhaust? It would make sense concidering the back-fire. And just to be sure,,,,, we are not REALLY talking about "back-fire" which technally means it would be firing through the carb right? What you are really getting is unburned fuel in the exhaust, which when it ignites, goes boom! What happens is the unburned fuel builds up in the exhaust (like when engine braking) until enough "air" gets mixed with it for ingnition. If you have a hole in the exhaust system it will occur much more often because it is easier to find the extra air needed for ignition. If the exhaust is completely sealed, it is more likely to happen when you turn it off. Because it has happened frequently, it is quite likely that you now have a hole or blown gaskets. You also say it happens on turns, so it sounds like float levels or stuck float, again running toooo rich.

xman

Also check your fuel filter and make sure it's not plugged. That could cause the major lurching when accelerating. Also do the checks for good spark at the plugs, mixture/idle checks as well. The backfiring could be caused by a bad shuttervalve. If you hear a whooshing/honking type noise when accelerating that's a good sign it's bad. This valve is suppose to lean the mixture upon deceleration to prevent backfiring, but they seem to go bad after about 80K.

smile444

Ok,

Damon: The fuel filter is stock. Only the cats are gone, the rats nest is still there. I would remove it, but I don't have a header yet (I want to get a Racing Beat Header). Can I safely remove the rats nest with the stock exhaust on this car? The two lines that used to go to the cats were already capped off when I got the car. I had the cats removed. The carb is kinda intimidating to me. I am learning. I do not see two windows on the carb. I don't have a fuel pressure regulator, but I will get one tomorrow! How do I use it?

Jeremy: I had the spark plugs replaced with top of the line stuff. I believe I am running rich. I played with that screw in the carb, and I can't get at it to tighten it anymore. Without applying some serious torque, it would be hard to screw it down any tighter to get it to run lean. The constant sputtering/lack of power is the worst. The Rex has no get up and go. I am suspecting that is the fuel filter (have to learn to replace that tommorrow). It may be plugged because I put carb cleaner additives in the last three tanks of gas.

Racermike: Ah the float. I don't know yet what that is, but being the good teacher that my Rex has been, I am sure I will know very soon. Also, is the overflow in the carb that little screw that I can turn to run it richer or leaner? The backfires that I am getting are definately the unburned fuel in the exhaust. It goes "boom" real well. I have to re-bolt the joint at the gasket, it is currently not tight (= air for backfiring). I suspect that there could be a hole(s) in the exhaust pipe up front under the heat shield (I am getting noise from there). How can I fix/replace a float, how hard is it, and how much would it cost me?

Xman: I will check the filter tomorrow. I think is by the back driver tire. Is it hard to replace? Spark plugs are brand new. Also this shuttervalve thing you mentioned is probably jacked as well. I have experienced the "whooshing" sound with the backfire 3 or 4 times. Is it easy to get to and replace? Is it part of the carb?

You guys are so damn cool for helping. I don't know anyone else who has or loves 7's. I look forward to being able to help others with knowledge soon.

One more question::

I just disconnected my air pump, and removed it. I plugged the tube that runs to the carb after I removed it. During my 3-4 hours of searhing the threads last night for info, I thought I saw something about it being very bad and/or dangerous to remove the air pump without also disconnecting or doing something else as well. Umm, what would that something else be? I don't want anything to not get enough air, heat up, and catch fire.

HELP!

Merry Christmas ; )

85RX7GS

iTrader: (1)

Check the dashpot to be sure it's getting a signal at the correct RPM.

inittab

dash pot? signal? Surely you're kidding right?

85RX7GS

iTrader: (1)

Come to think of it, rebuild the carb.

nimrodTT

Did you ever check your timing?

smile444

I will try to check the timing today. I've never done it before.

Hey y'all, what about the removal of the air pump? Is there anything else that I need to do when I disconnect it?

xman

Smile444, if you've experienced the "whooshing" sound from the shuttervalve then that is probably why you are getting the backfiring. this valve leans the mixture on deceleration. When they go bad-mixture's too rich and voila, your neighbours curse your name if you work early in the morn! Check out this site for more info on the valve and how to replace it:

http://www.mazdatrix.com/faq/shutter.htm

I live in CANADA and when mine went bad I did a price check at the local Mazda shop, and unless the old guy was trying to jack me the quote was around $260.00 for a new one!!!! Seems way too high, but you might be able to fandangle one for a better price down there. Just some advice. Don't wast your time removing it if you're going to try and replace it with a used one, cause it's not that easy to remove unless you have the right tools (the carb nut that's closest to the driver's side/firewall is a !@#% to get at!
What you can do is plug the rubber tube that comes off the valve with a large bolt (make sure it's air tight) and plug the hole in the air filter housing the tube attatches to. This is easier than replacing the valve itself.

As far as the air pump goes. It basically just blows air into the exhaust for emissions purposes. Removing it will gain you only around 1hp, so removing just gives you a little more room to work around in the engine.

The fuel filter is located under the car on the driver's side just before the rear wheel. It will have two fuel lines clamped on to it on either side. If it's been changed with a new one it should be white or clear plastic. You will need to jack the car up and have some pliers to remove the clamps. Not very hard to change. Make sure you have some rags to catch the fuel when you've removed the clamps. A new filter should cost under $5.00. You should check this out before messing with your carb if your car is having problems accelerating (i.e. doing the "herky-jerk" when you punch the gas. Try changing the filter every tune up (at least once a year) or more if your gas-tank is rusty, etc.

As far as rebuilding your carb. Get a cheap used one from a wrecker and try rebuilding that one if you haven't done it before. At least that way you can replace it with your old one and still have you vehicle drivable if you've messed something up.

As far as removing the rats nest and other emissions items. If your not sure about it better ask/find someone who knows what must still remain connected. There are a couple of vacuum hoses that still need to remain attatched or your ride will not work well. Not sure if there are any good posts regarding this. Mine is removed, but it's been a while, and I can't quite remember what needs to remain. Removing the ACV (air control valve) also accompanies removal of the rats nest, and this requires you to cover the hole with a blocking plate (these are sold at Mazdatix), or you could fabricate one yourself if you've got the tools.
Anyway, hope this helps.

85RX7GS

iTrader: (1)

Check both anti-afterburn"er" valves too. It's really easy - in the Haynes manual.

racermike

The overflow is inside the carb on the drivers side, triangular "bucket". Normally it will be dry. With engine running, check to see if there is gas / gunk in it. It was the "going around turns" that make me believe you have carb prob.. Messing with the floats you do during a rebuild or cleaning. The sight glasses are on the side of carb (front and back),,,,you can probably only see the front one, and will probably have to clean it off to see the gas level.
Shutter valves ARE expensive. Even disabled I have seen them stuck in the wrong position. It opens an airway (inside itself) AND opperates a butterfly in the intake manifold by the mechanicl linkage.

smile444

This morning, I went to a salvage yard and pulled off a carb. It was a biotch to get at (driver-side firewall bolt). I decided it would be fun to remove a rats nest. Out came the hammer! Wham Wham! It was fun bashing it (ha ha), but I also got to see where all of those hoses go. It turned out that they were too proud of that carb, so I am going to go to a different place in a few hours and pull another one. I also ordered a rebuild kit. Target is Christmas morning to have a rebuilt carb. Family will probably delay work.

I did see the shutter valve, and it might still be in my toolbox. I'll hafta check. It seemed broken/stuck, perhaps it could be cleaned/rebuilt?? My friend and I will see if we can do that.

Also, I have an 83 GSL that runs fine, which I am planning on selling. It has a new sweet iradescent silver paint job. I plan on putting it on Ebay to see if anyone loves it like I do. I will try tp put pics up here in a few days when I get it back.

xman

Back in the day I tried to replace my old defective shuttervalve with one that I thought was in good working order......turned out that it was a dud too! What big waste of time!!! Since the carb is so difficult to remove without the proper wrenches I would be hesitant replacing it with a used one unless you knew it was good and came from a working X.

smile444

There has to be a way to test a shuttervalve before you put it on. Any ideas?

racermike

Sure, the vacumn hose (small) is the control. When you suck on it , it does 2 things, it opens the airway connecting the big hose (to air cleaner) to the valve body (allows straight air into the intake) and it pulls in on the linkage which controls a butterfly in the intake (this restricts air/gas from the carb and directs the straight air instead).
The usual failure is that when sucking on the small hose, there is no restriction, so NOTHING works.