Ignition trouble when hot

[kustom]

I am stumped! I thought I had things figured out on my 1981 electronic ignition spider, so we went on a 4 hour road trip. Everything was good until about 1 hour in, the engine started to sputter and die. The coil was super hot. Luckily I was close to a Napa, so I bought a new coil, and continued. Another 45 min down the road, the same thing happened, the coil was super hot again. I switched back to my original coil, and continued switching as necessary until we got where we were going. My 2 coils are 1.7 ohm across the primary. I have 12 volts off the positive cable, so I thought I would try a 3 ohm coil. Now my car will start and immediately die! My friend who was with me on the road trip said I should have bought British as he laughed at me and flew past in his Spitfire. Help me prove the limey bastard wrong!

[Danno]

Are you sure it was a spitfire? usually the cloud of burning oil makes identification pretty hard.....

Also, are you sure it was the Dizzy getting too hot that was the problem? I mean the time it took to change it out each time could have allowed whatever else was having issues to cool off.

[kustom]

Unfortunately, yes it was a Spitfire and I was choking on the smoke! I'm sure the dizzy isn't hot, but I'll check it out. I didn't want to admit to this, but one of the road side fixes I did was putting the coil in a slurpee cup with cold water to help cool it. It actually helped get me home.

[Danno]

I'm sorry, I mistyped. I didn't really mean to aim you at the dizzy. I was typing dizzy when I meant your coil. I was trying to point out that in the time you replaced your coil something else could have been cooling off just enough to make the difference.

[So Cal Mark]

ignition coils do get hot! That's why they are filled with oil; to help cool them. My bet is that the ignition module that mounts under the coil on the heat sink is failing

[billstyer]

Just throwing in my two cents worth. Mark is the expert, but I'm thinking hot coil is just a red herring. While you are busy changing the coil, the pickup inside the distibutor has a chance to cool off. My '81 FI would run fine, and then die when it got good and hot. I could make it all the way to work in the morning, but it would die halfway home in the afternoon. Let it cool off for 10-15 minutes, and I could make it the rest of the way home. Changed the pickup and problem solved. For what it's worth, I'm betting on the pickup.
Good Luck!

[zachmac]

Also, now don't get mad, make sure you don't have the wires reversed where they hook up to the coil.

Don't laugh, I found this out the hard way on an E-type Jaguar. If you happen to reverse the neg. and pos. leads to a coil the car will run BUT you are now using the coil as a step down versus step up transformer. It will do exactly what you describe, run okay while cool and get real hot real fast until it quits. I had a friend point this out to mo on the Jaguar as when he was a teen he picked up a brand new E-type with his rich girl friend in manhattan to drive it out to her dad's house in CT. they got about halfway there when the car quit. They finally figured out that the factory had wired the coil backwards. Revese the wires and Bingo! off to the races.

[baltobernie]

Also eliminate the possibility that the ignition switch is not intermittent. When the car dies, leave it coasting in gear. Wiggle the ignition key back and forth (caution - don't go too far counter-clockwise that the steering column lock is engaged , or that you engage the starter going clockwise ). If the car comes back to life, rebuild the ignition switch.

For you guys that are beginning ground-up restorations, unless your intent is concours, consider rewiring the car to modern specs, and get all those switch-destroying items off that circuit. PM me for conversion details for carb cars; FI guys maybe take a look at my article and contribute for Your Generation.

[mcane227]

I'm certainly no expert, but I had this situation with my 82 spider shortly after I obtained it last year. Car would drive fine for 45 minutes, then lose power and sputter out. Let it cool for 10 minutes and I was on my way for the next 10 minutes, only to pull over coasting to a stop with a dead engine. On my second trip to the shop, my mechanic checked everything and finally checked the fuel pump which had recently been replaced by another mechanic. They put a gauge to measure the flow and ran the car until it got hot. Low and behold, the flow dropped off when it was hot. The fuel pump was bad, and apparently they can partially fail when hot, and when cooled, will operate OK. When they replaced it with the correct part ( the first replacement was incorrect), they not only replaced the filter between the fuel pump and engine, they added a second filter between the gas tank and the pump. No problems since then!

Just a thought. Goo luck.

[james124]

they not only replaced the filter between the fuel pump and engine, they added a second filter between the gas tank and the pump. No problems since then!

That is a great idea mcane. With our old rusty fuel tanks, we should all be considering adding the extra fuel filter. James

[Danno]

they not only replaced the filter between the fuel pump and engine, they added a second filter between the gas tank and the pump. No problems since then!

That is a great idea mcane. With our old rusty fuel tanks, we should all be considering adding the extra fuel filter. James

not discounting the filter before the pump, but pumps are better pushers of fuel than pullers of fuel, so adding resistance before the pump might shorten its life. although, the point being made is that crap in the tank could also shorten the life of a pump if it's continuously sent through it. I guess the best case scenario is to not have a rusting fuel tank, then it's not a worry.

[htchevyii]

Richard Ridge on Mira came up with this prefilter from an Audi. It is more of a strainer and should flow pretty good.
Here's the link:
http://www.flickr.com/photos/rridge/4607639950/

I think the Fram number should be G6399

[kustom]

I have an ignition module and pick-up coil on the way from IAP. Hopefully they do the trick. If not, I'll be trying the fuel pump. Thanks for all the tips so far!

[kustom]

So the problem is finally fixed! I installed the new ignition module (worked fine) and pick up coil (was faulty out of the box from IAP), so put the old coil back in. Things were running ok, but not great. We left on our annual trip from Southern Alberta over the Logans Pass to Kallispell Montana with the Spider,Triumph Spitwad, and Mini Cooper S. This is one of the nicest mountain road trips you can make. The Spider ran great going down, but started missing pretty bad on the way home at the end of the weekend. It made the 340 mile return trip, and stalled outside of my house. I got it back into the garage, and had to wait for the replacement pick up coil from IAP. Sure enough, that was the problem... The new pick up coil worked like a charm and the spider is purring again . Thanks to everyone for the input, it's nice to have help from such an experienced group! If you're ever in Northern Montana, I highly recommend that drive! I'll post some pics later.