Fuel management?

[festfull]

I have a 92 5 speed festiva with 199,XXX miles. I go out to the car it fires right up and could run all day. In the event that I turn it off to get gas or run into a store the car becomes hard to start and runs like crap for a while. Acts like the car is flooded. It will get to the point that the car will not start. I leave it alone for a few hours and it will fire right back up.

I have done a number of things to it to fix/ID this problem. I'm looking for a fresh idea and a different perspective. I don't want to point anyone in the wrong direction so as ideas come in I'll go into more detail to what I've done. Thanks

[mudder]

I am having the same problem with my 93. In this current heat wave that is scorching Michigan if I park it in a hot parking lot on re-start it acts like the fuel is percolating in the system and making it run rich. Never had this situation before in other hot summers, I wonder if the evaporative emission control system is contributing?

[JohnGunn]

Sounds like an electronic component of the ignition system has begun to die and the first signs are failure at high temperature. This is a fairly normal pattern of failure for electronic components in computers as well as automobiles.

When you turn the engine off, you stop the cooling processes designed into the system -- the water pump stops and some parts of the engine actually get hotter due to that. This extra heat could be enough to push the failing component beyond the point at which it is capable of functioning.

My first guess would be the Crankshaft Position Sensor located in the distributor, which gets very hot because of its location. Touching the distributor is enough to demonstrate that. Next would be the Ignition Control Module which in earlier Festivas was located in the distributor, but was moved to a cooler location away from the engine in 1990 -- driver's side strut tower.

In your situation I would use some Brake Kleen or some other cooling spray to cool these parts, the outside of the metal part of the distributor and the ICM, to see if they recover more quickly in response. If you do this, disconnect all electrical connectors and be careful to keep the spray away from other neighboring electrical connections, especially any that have been wrapped with electrical tape. Otherwise the tape will loose all ability to stick and will have to be replaced.

On second thought, before using expensive sprays, I would first try keeping the suspect parts damp with water from a spray bottle. The effect will be less dramatic but still effective enough to establish whether extra cooling reduces the time needed for the parts to recover.

[Occhty]

Next time try taking the gas cap off, that will rule out vapor lock. I've never seen it happen on efi systems, but have seen it on carbys.

[festfull]

Thanks for the ideas. I replaced the ICM and still have the same problem. The car could be running for five minutes or five hours. It always stumbles on restart. You think a new disty will fix the problem. I think i can pick up a younger distributer. I've already replaced the coil, cap, rotor, plugs and plug wires.

[Pu241]

I'd clean the one I had before I'd buying a new one.
Unless you can get another known good one for reasonable.
Or borrow a know good one to see if this is the issue.

[Zanzer]

I had the same problem on my 93 until I swapped in the fresh Aspire motor. I highly doubt the Aspire motor was the fix but I did a couple of things while I had the engine out and when I put the new engine in. I cleaned the injectors and replaced the filter baskets in the inlet end. I don't think this effected it much since the old ones were quite clean considering the 208k on them. I also cleaned the throttle body and it need it pretty bad. The last thing I did was to replace the VAF (the cover needed re-sealing on my old one) and I cleaned the replacement VAF really well. It had some oil and other debris and crud in it so I took a can of carb cleaner and sprayed it out to clean all the gunk out of it until it looked new inside. I cleaned both sides of the door, everything in and around it, and every orifice I could spray out. I then verified the door operated smoothly and didn't have any snags or tight spots in it's travel.

Since doing all of this I haven't had the hot restart problem since. I'm wondering about the possibility that the door in the VAF could be sticking slightly open after the initial cool startup, so when the car is cranked again after a recent start, maybe it's getting a little extra fuel since the VAF may not be completely closed. A couple of theories on why it didn't do it when the engine was cold 1) A cold engine requires a slightly richer mixture so maybe it's not as sensitive to the extra fuel, or 2) When the car sits for a long period of time (long enough to completely cool) maybe the door in the VAF slowly goes back to it's home position.

As I said, this is all just theory and conjecture on my part so someone else may have a better idea of what the problem is. All I can say is that my issue went away when I replaced the VAF with another used one that I had thoroughly cleaned. So maybe try cleaning yours to see if it helps. Most I've seen have needed a good cleaning anyway so it's sort of a win/win situation. If it solves the problem, then great. If it doesn't, at least you know the VAF is clean and you've possibly eliminated a variable.

[festfull]

I swapped the VAF from my daily driver and the problem is still there. My daily drover runs great with the questionable VAF. Also replaced the valve cover gasket and pulled the throttle body and didn't notice any build up but can take another look. Thanks for the input.

[JohnGunn]

Thanks for the ideas. I replaced the ICM and still have the same problem. The car could be running for five minutes or five hours. It always stumbles on restart. You think a new disty will fix the problem. I think i can pick up a younger distributer. I've already replaced the coil, cap, rotor, plugs and plug wires.

First, I should tell you to consider very carefully everything Zanzer writes concerning your problem. He and I don't always agree, but his mind is clear and he's had a lot more experience and seen a lot more of these cars than I ever will. Certainly cleaning your VAF meter on his word alone would not be amiss.

The most important thing I take away from the description of your problem is that it is related to the running of your engine, and that suggests to me very strongly that heat is a key factor in triggering the problem. In your latest post you say that it stumbles on restart after running only five minutes. Maybe you could use this information to study the problem in more detail.

Of course, it's a lot easier to study a problem which either works or doesn't work as in, after running for an hour it refuses to restart until it cools down for a couple of hours. But that takes time to reproduce. If the problem evidences itself in a more subtle fashion after only 5 minutes, you could study the problem by backing away from that failure until you found the exact time were the problem first appears. Then by using your hand to measure the temperature of the distributor you could establish the relationship between your stumbling engine and the heat of the distributor.

Just had another thought which you need to answer for me. If the stumbling you experience on restarting after 5 minutes running, goes away as the car continues to run, then that would discredit the theory that the problem is heat induced, since after only 5 minutes running, on restart all parts are only going to get hotter. And if heat causes the engine to stumble you would expect the stumbling to continue or even get worse as it continues to run.

That being said, it occurs to me another electrical variable is at work when it comes to starting an engine -- the voltage provided by the battery. The thing that makes these cars fun to diagnose is the complexity of the system, but at some point, the smartest thing to do is to stop thinking and start acting.

After cleaning your VAF meter I would suggest you try and identify the exact point at which the stumbling, you mentioned seeing at restart after 5 minutes running, starts.

I might do the following:

When the engine has cooled over night start it. I assume that first start works perfectly every time when the engine is this cold. As soon as it starts, turn the engine off. Feel the heat of the distributor with your hand. Then do that again. I would expect the engine to continue starting for a long while if each time it starts you turn it off. Let's say in that process the engine runs for 5 seconds. In order to generate the heat of a 5 minute run you could start and stop the engine 60 times. Three or four more of these short restarts should be enough to establish that it is not something about the first start that is exceptional.

Then I would let the engine cool down for an hour or so until you can feel no heat at the distributor. Then start the car and allow it to run for 60 seconds. Feel the distributor and restart. If it starts correctly allow it to run for another 60 seconds and repeat that routine until you notice the stumbling. From that point on you would expect the car to stumble every time you start it. Test this by immediately starting it and turning it off, a couple more times. If it stumbles each restart, take a water bottle and spray the base of the distributor until you can feel that it is noticeably cooler to touch. Then restart and see if the stumbling has gone away.

Well, I'm sure from that you get the approach and can take the idea and use it in any way that serves you best. Good luck and keep us posted.

[festfull]

I have spent the better part of this past weekend. Working on this car. I started with the cheap and straight forward things. I am now to a point where I might start costing me a little money and time. So as always I'll have an open ear to an idea but I have the ability to filter out something that i believe won't help or is a non issue.

This car is 100 miles from where I live so I don't have the ability to work on it every-night after work. So the time I do spend with it needs to be well spent.

The car's first start is flawless. Any start after that is increasingly more difficult until it will not start. On the hard starts the engine will stumble for a while and put out a little black smoke. I believe this to be excess fuel. The car will right it self given time but as soon as you switch it off it's back to the hard start if it will start. I've ran the car for 30 min then restarted with little problems and I've started it up perfect and restarted just that quickly and nothing. There is a problem it's just hard for me to pinpoint as it is inconsistent. The things I've done have helped but not fixed. It seems to be a electronic/heat/fuel issue.

This is to me like a great book. It let's my mind think of things I wouldn't other wise think about. All the twists and turns that must end up in a happy running festiva.

Thanks for the ideas and input.



Thought I'd show you what were working with. It's the green car in the middle.

[fastivaB6TG25MR]

put a fuel pressure gauge on it and see if an injector is leaking after you shut it off