80 project

When the car is cold (motor has not been run in more than a few hours) it will not maintain an idle until it warms up. After that, it will idle fine. I replaced the fuel filter, cleaned the carb and linkages, did the timing, checked the plugs and they look fine. The choke will close all of the way, so I am assuming that it is ok. I pulled off the air cleaner and checked for vacuum leaks and could not find any. I even sprayed "quick start around the carb and on the lines to check for a change in idle. I cannot find the problem. I have already searched the forum.

I have to get on and off the gas rapidly to get it to run. If I give it part throttle it will die. I cannot just hold the gas. I have to feather it constantly.

The car drives fine and has good power. I just got the car a few weeks ago, and don't know the history of it, or how long this has been a problem.

I need some help.

zookeeper

Although you said the choke closes all the way, it still sounds like classic choke-no-work syndrom to me. Does the choke close when you pull the choke ****? or just when you manually check it at the carb? Does it stay closed when you start it?

Try this: Remove the air cleaner. Start car when cold. Cup your hand over the carb opening so you block off a good % of the air. (If it'll run long enough for you to get out, if not - get a friend to help) If the idle increases and smooths out and then drops and/or dies when you take your hand back off - you've got a fuel problem. Choke? Partially clogged filter? Flaccid pump?
Partially clogged carb jets? Those are what I'd look at.

80 project

The choke operates when I pull the ****. It closes fully. The rpm's climb with the choke pulled, but it still quickly dies. If the car is warm and I pull on the choke, the rpm's will rise to about 2500. If I had a bad fuel pump, wouldn't it act up when the car is warm?

racermike

Even with the choke working, and you have to pump the throttle, means it's still running lean. (unless of course it runs better with the choke off)

80 project

When I covered most of the carb it ran, but smoked constantly and chugged. It was definately running rich. I pulled the plugs the next day and they were all black and fouled. I think it might be a spark issue. Would it make sense that if the plugs were weak, it would be hard to start when cold, but run fine after it warmed up?

racermike

Yes! Get new plugs and try again. If it still happens, you will at least know what it is not. You could also have a coil or ignitor problem. Put the new plugs in first. Then check them again after running a little while (a full heat cycle). Note what EACH plug looks like. If the plugs on one rotor are different than the other, it will help trck down the problem. Are you certain the timing is correct? If so try the timing light on all 4 plug wires to see if they all trigger the light and have no missed flashes.

80 project

I have double checked the timing on the trailing and leading #1 with the light. I have not checked #2 on each. I will do the plugs tomorrow to see if it solves the problem. Also, Do most RX-7's blow blue smoke on start up? Is that a sign of worn apex seals and oil into the combustion chamber? My 84 GSL-SE did it.

racermike

Most WILL give up some oil smoke on start up. It IS oil smoke, but it isn't apex seals but rather oil ring and side seals that leak. Oil is also injected into the enginge by the oil metering pump (OMP). Excessive smoke is a sign of age.

80 project

When I drive the car after it is warmed up it does not smoke at all. Even at WOT. Is that a sign of a good motor with good seals? I am still trying to figure out my hard cold start problem, but want to also know if I have a decent motor on my hands. Like I said before, it runs perfect with lots of power after it is warmed up.

80 project

I changed the plugs. It runs a bit better on start up, but will not maintain an idle and stalls until it is warmed up. I checked the vacuum lines again and found nothing wrong. I need some more suggestions.

racermike

I 've been trying to see if you have stated HOW you start the car and I don't think you have, so maybe we should talk about the proccedure. ((forgive me if I get too basic)) When you start the car cold, 1st, turn the key to "on". 2nd, pull out the choke all the way. (((the choke will NOT stay out if the ignition is not "on"))) 3rd, crank the motor. Depending on the individual car, it may or may not need to have the gas peddle pumped a couple of times. To help prevent flooding, crank the motor for 3 - 4 seconds and if it hasn't fired up by then,, give it a couple of pumps while you CONTINUE to crank it. IE... Do not stop cranking before pumping, keep the motor turning! If it hasn't started within a couple of seconds, pump it again a few times,,,,ALL OF THIS WITHOUT STOPPING THE MOTOR FROM TURNING WHEN YOU FIRST TURNED THE KEY TO "START". If it has not started within 10 seconds (from the time the key was turned to "start"), STOP, and let the starter have a break to cool down. Then try again.
Since you DO get it started, here is what to do next. Keep the choke pulled out for a while. Depending on temprature and other things, it should be "idleing" at OVER 1,000 rpm. If you do nothing else the "idle" speed will continue to rise as the engine warms up, up to over 3,500 rpm if you let it. It does NOT need to turn that fast so push the choke in PART WAY to lower the speed to about 1,800. You can "lower" the idle speed again when it climbs above 2,200. (((The "choke" is not "on-off", but variable))) Do NOT push the choke in all the way. It will go in by itself when the engine has warmed up and will not stay "out" if you try to set it when starting a "warm" engine.
If you are already doing these things (sorry) and the engine will not idle after the choke automatically goes in by itself, you have "other" issues. The temp. gauge should be in the "normal range" before the choke resets, although maybe NOT as far up as when it is completely warmed up. If you have had the plugs in for a few days, pull them out and note their color as well as their position to help diagnois the problem further. The best way to determine the condition of the motor is by doing a compression test. If you haven't done that yet, or do not know how (it is different than a piston engine) do it! You will eliminate a lot of guessing and have a much better idea about seals and such.
Good Luck! And let us hear back from you soon!
PS... If the only way to keep the motor running is to continuously pump the gas,,,,,,it is running too lean! Pumping the peddle "richens" the mixture because you are actually pumping "extra" gas into the intake.

80 project

When I start the car, I pull the choke and it stays closed even when it is warmed up. I am pretty sure that the automatic return is faulty because when the engine is warm, I can still pull the choke and it will stay out. Regardless of this, even with the choke fully closed on start-up, it will stall. It runs the best when I hold the gas at 3K rpm without the choke to warm it up. I have experimented with different ways and this is the best.

Once it is warm it runs great, but if I hold the rpm's between 1K and 2K it seems to stumble a bit. This makes it hard to engage the clutch on take off and it will stall unless I give it some more gas. Normal driving is great otherwise.

I don't know if it is lean or rich on start-up, or just an inconsistant fuel delivery. My next step will be to tee in a pressure guage on the fuel line to see if the pump is good.

I think it may be a carb problem?

I am fairly handy with cars. This is my 11th car in 9 years and my third rx-7. Don't worry about being too technical, I know the basics.

Any more advice would be great.

racermike

Well if the car runs best in a "choke" stituation without the choke,,,,it stands to reason that the "carb" is running rich. I wouldn't discount the "auto-return" on the choke as not being part of the problem, still. Adjusting the carb. may help with stumble.
Have you pulled the plugs again yet??? You don't have to replace them or maybe even clean them, but you need to pull them them to have a look see. You can sometimes tell by the condition and positions of the plugs what is wrong. Good time to do a quick compression test too! Do these things and you may pinpoint the problem. (((and fix the choke)))