Stalling after long drive - Coils?

Hey all,

So I've had my 1978 308GTB on the road for a couple of months now and I've driven her about 300 miles. Thursday I took her on my first long road trip, 2.5 hours. Everything was going well until the end of the drive when the car started stalling as I pulled up to stop signs. The car would start right back up and seemed fine, power-wise after pulling away.

While all my engine temps were spot on, I'm wondering if the coils were starting to go after getting really hot. They look like they're very old, perhaps even original.

I went to start the car today and everything seemed usual. Is this something I can test or check? Does this sound like a coil issue?

I'm a little concerned about getting back home on Sunday!

Thanks,

E

 

What is your idle set at. Also are the carbs clean and linkage all working correctly. When was the last time the carbs were tuned . Did this happen with AC on or off. Is the timing correct and is the advance working correctly. What about points.

 

I have the same issue with my 348 once it hits about half a tank, when fuller than that it never does it.

I'm wondering what it could be.

 

Hey Steve,

Thanks for the response. I was visiting family up in the mountains of NC without any specialty tools to speak of. I went the MacGyver route, removed the caps and cleaned the contacts with a penny. I then lit some votives around a picture of Enzo and set off home. Car made it back without issue, although idle was rough it had quite a big of popping.

Time for an electronic ignition!

E

 

Sounds like the R1 points are going if it only happens at idle....

 

I've been thinking about your stalling problem. I had a similar issue with my '77. I even followed your thinking about maybe it being coils. The thing is that it is unlikely that both your coils would fail at the exact same moment. I would take a look at the ignition control relay. I had a condition where the car would start and run fine, then when warmed up, it would stall when I went to idle. In my case, it wouldn't start again until cool. I scratched my head for a while over that one.

I think what was happening is that when the relay got warm it would get hung up between its two states and so I would not get clean power to the running state and I wouldn't get any power to the starting state. I am running with a single set of points per distributor. The ignition control relay switches the power between straight 12v to the coil to start and then to a ballast resistor mounted on the coil that gives you 9v when running.

It was such a cheap and easy thing to replace that I figured what the heck, replace it and see what happened. I haven't had any stalling since and I'm probably running a little cleaner, so it worked out for me. Maybe that will help you too.

 

Hey David,

Thank you for your reply. I made it back and haven't really driven the 308 much, as I've been wrenching hard on a '72 E9 coupe I accidentally purchased.

Getting back into the 308, I was trying to find this relay. Is it in the engine compartment or in the fuse box? I can't seem to track it down. I figure if it's easy to find and swap, I might as well go ahead and do it.

Thanks for your help,

E

 

It is where the relays are. Located behind the panel on the passenger side that you remove to see the fuses. The two fuse boxes are at the right side. The relays are all located to the left. I don't have my manual in front of me so I can't guide you to the exact relay. If you have the manual you should find it easily. If not, let me know and I or someone else will give you more info.

 

If you have a 1978 you don't have one -- that "put extra voltage on the coils for starting thru a ...006 relay" architecture was only used up thru 1977 models.

However, david's point about ensuring +12V power is present to the coils is still valid -- what's important on a 1978 is that the top terminals of fuses #1, 2, and 3 are well connected together electrically -- and this relies on the rivets+plates on the fuseblock which are known to get flaky. A good reliability improvement IMO is to add a better form of high-current-capable electrical connection between the male terminals at the top of fuses #1,2,3 (like either soldering the rivets to the plates and/or soldering some busbar across the bottom of the male tabs) rather than just relying on the mechanical contact at the rivets to also be the electrical connection. If you search on something like "solder rivets" you should get (probably too many ) prior threads with photos/discussion.

 

@Steve - Thanks for chiming in! I was going through the manual and trying to find it and just couldn't... now I know why!

I checked the fuses boxes the other day and everything looked to be in really good shape. I will give them another good once over but I really haven't had any running problems since I returned from my trip.

On a related note, Tim from BSM in Australia expects to have some of the 308 single distributor electronic ignition systems ready in the next month or so! I've been pestering him hard about them so hopefully I can get one of those installed this winter.

Thanks for all the help guys!

E

 

Always a good thing to not have any obvious evidence of things melting/corroding/burning, but that really doesn't confirm that a good electrical connection exists (nor inspects the backside of the fuseblocks).

Putting in a "better" ignition system can actually make this problem worse as, typically, a "better" ignition system draws even more current than stock = increases the I^2*R heating at the rivet connections between the tops of the #1 and #2 fuses.

 

Steve, That is a subtlety I wasn't aware of. I know the 77's have some unique features, and now I've added another one to the list. Thanks for chiming in on this. I would have hated for Evan to have spent half a day looking for something that didn't even exist on his car. Although it sounds like he may have done just that.

I still stand by my reasoning that it is highly unlikely that both coils decided to fail at exactly the same moment. I like the thought of making sure the mechanical electrical connections are actually solid electrical connections. And I certainly agree that just looking good doesn't insure that it actually is good.

 

I'm not a 308 owner so forgive me for not knowing this offhand, but is your yours a single or dual distributor car? If it's single distributor, consider the pickup coil inside the distributor. It is not uncommon for those to show the exact symptom you describe. Ditto ignition modules, if you have one if those.

One way to isolate the problem is to carry a can of component freeze (available from electronic supply houses and some car parts stores), along with enough tools to access the distributor pickup coil(s) and modules (if applicable). When the problem presents, freeze each component in succession until you find the culprit.

Good luck and please post what you eventually find. .

 

North American cars are dual coil, dual 4 pole distributors (to make room for two sets of points in each one!)..

So, to the OP, simultaneous failure of both coils would be very high odds.

Now, vapor lock, from heat on fuel lines, or modified/plugged tank venting tubing, or something like that...more likely.

 

After reading again the initial post, I say "fuel supply".....

The old rubber lines rot inside, so rubber bits (or just fuel tank trash) can impeed full flow.

It would be a good idea (on age of you car) to redo all of that system, but if the filter has become loaded (or the fuel pump is failing) then a lack of fuel pressure would present itself as you have described......

 

When long periods betwen drives, the ethanol can seperate out, in the tank and the boundary layer (between alcohol and gas) is VERY corrosive, attacking the tank itself.

So some Stabil type fuel products, or fueling up between drives (to move the layer location in the tank) is a good idea.

 

I agree with the fuel issue. Another might be some fouled plugs. They may just show up at idle. An easy way to see if your fuses are lacking is to touch them during a long dive. If the are hot you probably have a bad connection.

 

Check fuel pressure. Make sure the check valve after the fuel pump holds pressure. You can check ignition by simply pulling the spark plug wire and having someone crank to car to see if you have consistent spark (play end of plug wire near a valve cover nut).

 

Quick update as I have chimed in earlier on this thread. I had initially suspected a relay issue, which sounded pretty intelligent. But... First the OP's car isn't carburated, so he doesn't have the relay. Second, this was a solution that I thought solved my stalling problem.

I was wrong.

I took my car out a while ago and it up and died on me despite my new 14 dollar relay. So I went back to the drawing board. A number of people have suspected fuel delivery issues. So I thought I'd replace the fuel filter and see what happened.

Fuel filter replacement was made very easy by some step by steps on this site. (Thank you.) I did the clamp on the inlet line and undid the fuel filter. Very little spillage that I caught in a pan. The housing for the filter held about a cup of gas. And that was it.

I just took the car out for a test drive and tried to make it stall or die. So far, so good. I think I'm going to dial the idle up just a bit. It's probably around 700 RPM, so I'll maybe get it to 850-900 and it will be a little happier. But it does lump along at 700.

I think I will have to take a few more test drives before I'm 100% convinced that the fuel filter was the problem. But I'm certainly more optimistic. Note that I have new fuel lines from tanks to carbs. And I use ethanol free gas. So it could have been bad gas or an old filter, I don't know. It's been said many times, this board is an amazing resource. Thank you.

david

 

Well David,

Did your fuel filter solve the problem?

 

When the engine cuts out, put your hands on the coils and they both should be cool. If 1 is hotter than the other then the hotter 1 is the problem. Normally when this happens you get it misfiring but this is not your case.
I used to have mine cut out when i took my foot off the gas, but mine was the injection mondial- it turned out to be the injectors, we cured this by putting a shot of redex injector cleaner in the fuel tank every year and no problems.
You might want to try the redex carb treatment or what ever you have locally, easier than taking it to bits as a first try.

 

When the engine cuts out, put your hands on the coils and they both should be cool. If 1 is hotter than the other then the hotter 1 is the problem. Normally when this happens you get it misfiring but this is not your case.
I used to have mine cut out when i took my foot off the gas, but mine was the injection mondial- it turned out to be the injectors, we cured this by putting a shot of redex injector cleaner in the fuel tank every year and no problems.
You might want to try the redex carb treatment or what ever you have locally, easier than taking it to bits as a first try.

 

So far, so good.