Dead again
 

I posted my original problem on the CR forum here and thought I had it solved, but my little black car left me stranded again today, although it did start up and run long enough to get home. Figured I'd throw it out to a wider audience (and I know Don Scott, DV, and the rest of the CR contributors keep an eye out over here for folks in distress!).

What happens is that I seem to lose spark. The engine just dies, and it doesn't matter if I'm running at x% throttle, or clutch-in coasting. I have an all-Mallory ignition system (HyFire box, ProMaster coil, and Unilite dist), and recalled messages here about Unilite durability problems. My failure is intermittent (aren't they just the best kind?), and because of that, I tend to rule out a module failure (though I'd be glad to hear from anyone who has solved an intermittent failure by replacing the module). What I found that I thought had solved it was that the coil-side boot for the coil-to-dist wire was too long to get good "positive-click" connection with the coil. I solved that by taking 1/4" off the boot so that it clicked into place before bottoming out on the coil.

I would like to think I've got a failure somewhere other than with the Unilite, and since the coil-to-dist wire is the cheapest and longest wire on the car (with significantly more resistance, as well), I'm going to replace that next. Do coil wires fail? Today, I detached and reattached both ends of the wire, and got it started.

In other potentially related info, I had thought earlier failures might be heat-related, but the car was running at a very happy 190 when it died today. And while I was sitting on the side of the road, I was able to verify that I had plenty of fuel coming from the carb shooter.

From this point, I'll start checking for bad connections from the key all the way to the distributor.

Any help and opinions will be greatly appreciated.

Thanks,

JLW

I have a Hy-Fire 1V. Mine left me a few blocks from my house .Turned out to be the power supply. I have the glass fuses and the contacts whent bad .I had to replace the fuse block. Cost me twenty in parts and one fifty in labor. I also had a time with a 77 Toyota .It turned out to be several fuses that appeared OK wern't .The caps came off when removing the fuses from the strip.

Unilite
 

John,

I am running the exact same ignition as you, right down to the ProMaster coil and I haven't had any problems with the system. I have read several negative posts over the years concerning the Unilite distributer and module. I think most of the problems are a result of poor installation or improper usage. I don't think the Unilite module is very robust when directly driving the coil primary, sooner or later a current spike might dammage the detector section of the module. It is also imperative that a ballast resistor be used with that setup to reduce the primary voltage, and some guys may not have done this.
When used correctly (as you are) with the HyFire IV ignition control box, the distributer (and module) become merely an ignition trigger sending a low current signal to the HyFire control box. There is also a bypass plug that will take the HyFire box out of the system. When using the plug, you must be sure that the ballast resistor (not needed when the control box is used) is back in the primary circuit. This could be a usefull troubleshooting tool. Next time it cuts out on you, bypass the control box and see if it runs.

Steve

Just a thought, in one of my previous cars I kept having a similar problem that turned out to be the fuel filter. It would become restricted and the car would die. Replaced many things before I realized what the real problem was. The good news was that fuel filters are cheap. Good luck and keep us posted.

Clois

My issue was close, but not quite what Clois had. My car died inadvertantly on the highway. The fuel tank was not properly vented (vent tube was run to the filler neck itself) to the outside and a vacuum formed in the tank. After running a separate hose from the tank to under the top side of the chassis the issue cleared. Where is your tank vented to?

J, These are always tough to diagnose. Do you have power to all other systems when the engine dies? If the power draw through the circuit breaker is more than 60 amps it will pop the breaker. It will reset after a few minutes. If this happens the breaker will tend to get weak and start popping with less draw. I have had the unilite module fail at random times. Generally heat related. I guess the other thing to check is the connections and the terminals. I haven't had a problem with the length of wires.
Don

Question I used to just set the engine at 12° btc and set the distrib with a plug in #1 wire grounded and look for spark. That was in the points age. Im at inital start up point. Alot of unknowns. Will the Mallory unit spark by turning the distrib or does it only work when being cranked?

Thanks for the replies - I will check out the fuel filter, and check the tank vent. Since the car is a turn-key CR, can Don or DV tell me where to check that? I don't think that could be a problem since opening the throttle at the carb sent gas out of the shooters just fine, but I won't rule anything out.

Thanks, too Don, for the breaker pointer, although I don't think that's a root cause - the starter still turns the motor over, it just won't fire. However, the "sit for a few minutes and it starts again" behavior is consistent with that.

One thought that occurred to me this morning is that maybe I have a short in the wires between the module and the HyFire - when we put the car together, the friend whose garage I was using did a great job of soldering the green and red wires between the HyFire and the module harness, but they happen to be wrapped together at the moment - if they touched, would this cause a short in the spark signal? I guess I'll test that this weekend. I'd also like to test that pulling the coil wire kills the motor (just for my own "OK, that's really what happens" satisfaction) - am I risking a shock if I do that while the motor is running? Is there a way to be insulated?

Thanks again,

JLW

PS - since nobody replied to say "coil wires fail all the time", I'm going to guess that while I should replace it with a higher quality piece, the coil wire I've got isn't a problem.

J, The coil wire doesn't usually go bad and if it does it is generally corrosion at one of the ends. I wouldn't pull the wire with the engine running, you can have as much as 50,000 volts there. You could use a very well insulated set of plug wire pliers but with the cd type ignitions the spark can jump a long ways. If the 2 wires are touching to the distributor that would cause the engine to quit.
Don
ps. The tank vent is located on the top front passenger side of the tank. It should have a hose up to the filler.

Don,

That was exactly my problem. As the vent tube connected to the top of the filler neck, when the LeMans cap is shut it has a rubber seal all the way around it. Once all of the air is extracted out of the tank, it creates a vacuum and can't effeciently keep fuel flowing. I used to go 20-30 minutes then the car would die. After I removed the vent from the filler neck and ran it under the car and above the differential so that it was high enough to not drain accidently and was getting air from the outside, my problem went away. This acts like a can with two holes in it. I can post pics if you like?

Regards,

Ren;
Excellent post..... I think I will go home tonite & re-route my tank vent to avoid the same problem.
BigMike

Thank you Sir,

It was a real brain teaser for awhile. It made me think that all modern cars have a vent to the filler but the filler cap is vented and the filler doors usually don't shut tightly. I'll try and take some pics tonight. But I just ran it out of the Right Rear wheel well along the frame keeping it tied with zip ties. Went above the differential to near the top of the upper trunk compartment on the underside of the car. Just zip tie it there. No way water or anything can get to it, it's too high and in the center of the vehicle.

Let me know how it goes.

Regards,

Guys, I thought the standard LeMans cap (if there is such a thing) was vented. :confused:


Steve

Doesn't appear to be on mine? If so, it isn't enough. Running some rubber 3/8" fuel line hose worked great.

Venting the Fuel Tank
 

Thought I'd post a pic or two of how I routed the venting on my fuel tank. Didn't have any under car shots yet. Just be sure and tie the vent line higher than the tank itself so that you don't end up with a siphon!
Pics are in "View my photo gallery", to the right.

Regards,

Running a tank vent/breather
 

If you find your tank or cap is not vented and you decide to run a breather hose ... be sure to fit a filter to the end of the hose, it can easily be an entry point for dirt or bugs to build homes in.
:)