My '84 12A has been running like a champ until all of the sudden tonight. Came home from work, it was finally a nice day out, so I hoped in and was going to take her out for a spin. Only, she didn't want to start. She'd turn over, then catch but just sputter and die real quick. Almost acted like she was a little flooded. So I pulled out the trusty ATF, and after just a little convincing, got her started (and scared some neighbors). And she was running fine. Let her idle for a bit then took her out for a drive. Came back to my apartment complex and I had to slow 3 times (stop signs and speed bumps) and each time she'd drop to like 200 rpm but I could keep her alive with the throttle. Then, as I got ready to park her, she starting backfiring a few times, then a few seconds later as I was coasting into a spot, she just died.

I tried turning her back over, and it didn't sound normal. Almost like the starter wasn't working as hard to spin the engine and it was just kinda freely spinning. Almost like it wasn't getting compression or something. So I have no clue, but it didn't sound good. Didn't like the backfiring particularly.

Any ideas? Thanks guys.

 

I'll give ya my 2 cents. It sounds like a fuel or carb problem to me. First step is replace your fuel filter. If that doesn't fix it make sure she's getting fuel by doing a quick volume test - pull the main fuel line (the big one without the little metal check-valve thingy) off the carb and rest in a can of some sort. Turn the ignition to "on" and you should get about a liter or so in the can in the time period of one minute.

If you've got fuel, it may be a carb problem of some sort. I can't really help ya too much there, but I'm sure other guys will be able to.

There is a quick and easy way to tell definitely whether you have done something serious like popped a seal. You may want to do this first for peace of mind. It goes like this:

Pull all the spark plugs out and disconnect the wires from the coils so you don't have any power running through the ignition system. Now let the starter turn the engine over. You should hear three loud and distinct "pffftt" sounds coming from the spark plug holes everytime the motor turns over. They should all sound exactly the same. Now, if you get something else, like 2 strong pulses and then a weak one, you know you have a problem. Assuming this test goes well, you can rest assured that your compression is fine and something else is the matter.

From my limited experience and what you said in your post, I don't think you have to worry too much. I'm not sure about the starter thing. But if your motor was seriously blown or something, it would run like real ****, have no power and you would know it.

Good luck!

 

Fuel filter is about a week old. It is a see through type though, so I better take a peak at it.

This is just happening because autocross season starts sunday

Thanks, I'll start looking at fuel.

Here's the interesting thing about my fuel pump. It doesn't always run when the ignition is on. Only when trying to start the car, or when it is actually running. Seems like that should be normal though.

 

No, that's not normal. Are you sure about this?

Your fuel pump should run anytime the key is in the "on" position. At least that's the way mine works and every other 12A I've ever seen. The stock pump is pretty quiet, are you sure it's not running?

 

CORRECTION

The compression test advice I posted above is slightly incorrect. Only pull the plugs out for one rotor a time (ie. 2 plugs). Do the test, then repeat for the next rotor.
The big thing to make sure of is that the power to the system is disconnected, so you don't start the car on 1 rotor lol.

Sorry guys, it's winter time and I haven't worked on my car in a while.

 

sounds to me like you just need a new dis/cap rotor,spark plugs and maybe even wires.

 

My '80 was the way you describe. My '85 is the way he describes... the fuel pump is only on when cranking or when the engine is actually running. It also comes on momentarily when you first turn the key to "on".

The later cars have this setup as a safety feature (I assume it was begun in '84). In an accident, the engine usually stalls, and the controller kills the fuel pump. That way if a fuel line is broken, fuel will not continue to be pumped out of the tank.

On EFI cars it also kills the fuel pump if the fuel line is broken, period, because the engine will stall rapidly with no fuel pressure. A carb'ed car will run for an amazingly long time with the fuel pump shut off.

 

Interesting interesting.... thanks!

I remember a furious argument a bunch of us had in the Canadian forum about just this topic. I guess we were all right lol.

 

The fuel pump is an aftermarket (holley of some sort I think). The wires and plugs are relatively new. I did the plugs roughly 500 miles ago.

 

I give up. Tried to start her tonight after doing nothing but checking a few things, she started pretty easily (amazing enough for my car), idled rough for a few seconds and put out some smoke, then smoothed out and the smoke went away. Ran fine all night. Sometimes this car just makes me shake my head in wonder.

 

Your carb is flooding, and at low RPMs you are running very rich. This is why it backfires.
I would start by checking the sight glasses on the carb. When running, the fuel level should be at the half way point in the glass. It usually is'nt exactly where it should be with the engine off, but if you can't see the level of fuel because the bowl is full even when the car's off, then you have a problem - most probably with your needle and seat.
If the level of fuel is too high, it chokes off the primary step airbleed for that primary venturi, and your carb is only recieving 1/2 of the air going to the idle circuit. (Both primary step air bleeds go to the idle. Why they chose two jets, and not one larger one, I'll never know!)

There is another little mischevis thing that can wreak havoc with your carb; and that is the "float bowl vent solenoid". It's the plug that located directly under the fuel in-line. It has one wire hooked to it that goes to ignition switched curcuit.
This is purely an emissions CRAP feature.
The vent is a valve that closes when the ignition is turned off. It prevents fumes from being released into the atmosphere. The carb can't work unless it can breathe. (It would be like pouring out a bottle of water...Cut a breather hole in it, and it comes out easier.)
But if it is'nt hooked up, the problems are many and varied.

I'm certain you're running rich, but you should check all of your carb linkages to be sure the butterflies are all down. If your linkage is hung up on itself, you'll never get an idle.

And no more ATF...It's not a carb fix!

 

Yeah, I think ATF is actually about as far opposite as being a carb fix as is possible. Just for some reason yesterday, she acted like she wasn't getting compression when trying to start (like she was flooded) which is why I tried the ATF. But I think you are right on the running rich thing. This started up after I changed my fuel filter, which was pretty clogged. Guess the previous owner didn't change it recently. With the less restrictive filter, maybe it's getting more gas up there making it run rich. But one think I noticed, I thought I was getting more "putt putt putts" on throttle lift than I used to, and correct me if I'm wrong, but I'm guessing that basically a little bit of unburned fuel getting through the engine and igniting in the exhaust. I turned down my pressure regulator a half a psi real quick. Not sure that thing does anything anyway, haven't notice a difference. She did run fine last night though.

The bigger problem is that I know jack about carbs. Almost nothing. I know the theory behind how they work, and that's about it. I wouldn't know how to adjust it is the problem. Also, I don't really know where to find the sight glasses

Thanks guys.

 

Cletus,
Do you have a stock carb and manifold?
How cold out was it when you had the problem?
hanman