Stalling E-type

E-Type
1

My 1969 FHC has been a thorn in my side as long as I’ve had it.
I bought it at a collector car auction about five years ago.
I drove it home on the highway, a distance of about 30 miles, and then into my garage. Only about one mile on surface streets before parking.
The engine was flawless until I pulled into my driveway when there was one slight ignorable stumble.
The next drive, and every one since then have resulted in a stumble after about six miles or 25ish minutes, followed by more stumbles, backfiring and stalling within two more miles.
The car will only restart after a good rest, about 20 minutes. It will then repeat the symptoms after a shorter drive than the last.

It has lived much of its life in garages and being targeted by parts cannons fired by mechanics who routinely work on e-types and similar vintage sports cars.

Fuel delivery aspects of the problem have been eliminated with a thorough cleaning of the tank, a new pump, and a clear terminal fuel line delivering a constant 5psi of fuel with no air bubbles.

We’ve gone through many electrical parts including a new ignition switch, battery, grounding straps, 2 Pertronix ignitions, back to original points, multiple coils, with and without a ballast resistor, plugs, cap, rotor, plug wires, etc.

Today I decided to check the voltage to the coil with the engine off, and running/driving.

With the engine off, and the key in the run position, battery voltage was 13, and 11.5 at the coil.

While driving, coil voltage (no external ballast resistor) started at 5 volts and dropped to 4.4 while moving. When the engine revved prior to shifting, voltage dropped to about 3.2 and came back up to 4 with lower engine speed.

I’m hoping that this voltage is too low for the coil and it just gives up at some point.

If this is the case, could the tachometer be the culprit? If so how should I address it?

Grateful for all advice,
Dave in Miami, Fl.

2

I want to ask how you are measuring the voltage at the coil whilst driving and which coil terminal you are monitoring.
But to aid your fault finding why not try a jump lead from the battery positive terminal to the coil and see if your problem goes away. If so it’s just a matter of tracing the wiring and fixing the poor connections?

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Or it could be ground problem if the above jumper doesn’t help.

4

If you have repro Champion plug caps replace them with something else.

5

Yes, could be the tachometer if still the original your car would have been fitted with. I had to have mine - which like yours is the pulse type - converted to electronic after having installed a Pertronix distributor in order to get the car to run right.

One of the most difficult problems to find is an intermittent electrical short. These almost always occur at female spade terminals where the wires have undergone stress cracking. I would check the integrity of the wire terminals at the coil and distributor in particular but also the ignition switch and the bayonet connector for the tachometer.

Your symptoms also sound like fuel starvation. You say fuel delivery has been ruled out but don’t mention the fuel filter. Some of the aftermarket replacements don’t work with the E-type glass settling bowl arrangement, inasmuch they filter from the inside out rather than outside in. A suitable replacement is available from Carquest, p/n 86034. Best way to rule out fuel starvation is to take the top off one of the float chambers and take a peek right after the engine has died.

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6

Assuming that this measurement was taken at the negative terminal of the coil, I’m not sure that you can deduce much from it. One would expect the voltage there to be a complex waveform that ranges between 0v during the dwell period, and up to several hundred volts at the instant the points close, and back to battery voltage at the end of the cycle, all repeating 3 times per engine revolution. The meter will simply see the average of this waveform. Here’s a video with more detail:

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7

Many years ago my brother had a 69 mustang with the same problem. Run for bit, run rough then die. Wait 20 or 30 minutes and it would start but the same problem. I replaced the fuel filter and it ran great.

8

Some disambiguations:

  • It doesn’t matter whether the filter element is inside out, it still works. The only difference is that you wouldn’t see junk gathering on the element. That said, replacing the filter isn’t a bad idea. More about fuel filters:
  • It’s not the tachometer. The primary circuit loops through the tachometer, but doesn’t connect directly to the tach circuit. A bad tachometer will manifest as a bad tachometer, with no effect whatsoever on the coil primary.

I would be inclined to take out the ignition switch and test resistance across the contacts. It would seem that all the other logical stuff has been replaced at least once. Otherwise, my first shot would have been the coil.

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Are you able to duplicate any of the problems in the driveway and determine if when it will not start if it is a spark problem ? I have had a bad ignition rotors cause running/ starting problems. I have also had leaking floats in the ZS carbs to cause running problems. Have you checked for vacuum leaks ? Three of my cars are over 50 years old and especially over the last few years I have found it can be a combination of issues when they have these type of problems so I do my best now to not fixate in one area after the usual initial checks for spark, fuel, timing, compression.

David
68 E-type FHC

10

That Corvette filter has no reviews, who would pay $33.00 for a filter that I paid about $2.00 that is still working fine.

11

I’m remembering past discussions.

Not saying the tach is faulty (except maybe the bayonet connection - disconnect it and the car will not run) but this …

The thing about using an unsuitable fuel filter is the accumulation of dirt where you can’t see it, If on the inside of the filter, the dirt gets stirred up and temporarily blocks the flow of fuel and the engine stalls. Allow the dirt to settle back into the bottom of the filter and fuel will flow again, until the cycle is repeated.

If you use use this filter in place of the GF124 without reversing flow, then dirt will be trapped on the inside. There would also be a tendency for the filter to be pushed out of position by the flow

and

It’s like the GF149, but since the flange has been omitted, the filter is held in place with a spring. it’s really not a great solution. The spring makes installation cumbersome. Dirt is trapped inside, rather than outside where it can be seen

There’s also the possibility of dirt getting past an inadequate fuel filter and finding its way into the float chambers.

More info here:

12

You mention pressure, but have you checked that it has proper flow? Remember, pressure is just resistance to flow, so you could be measuring static pressure and think all is well but not getting enough fuel through the system.

Couple years ago I had a problem where after 5-10 minutes driving the engine would stumble and barely run, then start up fine the next day and run OK for a few miles before repeating. I went through much of the troubleshooting you have been doing, and eventually pulled the fuel line off the connection to the carbs and measured how much flow I was getting. It wasn’t nearly enough. I finally traced the culprit to a tiny piece of gasket material that had gotten loose inside the fuel filter assembly, which would clog the line. It would settle back in position overnight, and then get sucked back up again the next time I’d drive.

Check if the flow is adequate, and if so you can eliminate fuel starvation upstream of the carbs and focus elsewhere.

13

Dave
I had the same issue on my 69 etype. I went through all the same things trying to correct it. It turned out to be a bad connection on the Alternator wire harness. I still had the original harness in my car and it was as crispy as overdone bacon. When I checked all the connections a few were so corroded that upon removal they broke off completely.
If you choose to replace your harness be sure to label the old one accurately, because the new harness I purchased was incorrect at the three wire plug that connects to the voltage regulator. Another member had the same issue and I suggested the above to her and she found a bad connection on the wire harness. She just repaired it
Bad connections restrict the flow of current and when that happens is that the alternator works harder and overheats the coil . At least what I saw happening to mine, the coil used to get red hot and then it stumbled and made the engine misfire.Now my engine runs flawlessly and the coil is warm n not red hot.
It can also be just a bad ground due to age, clean up all the connections
Here are pics of my corroded wire and crispy alternator harness. As well as the new harness . Note the voltage regulator plug , the original pic is correct. I had to switch the ground wire with the F- wire
I used a voltage meter to ck continuity too
Good luck

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I think something is getting hot and becoming high resistance bad connection or broken wire somewhere in the circuits
Use a volt meter and check for line voltage loss
( result of resistance above )

15

perfect timing Jim, that was my issue
Exactly what I found

16

I had every one of these symptoms from a bad condenser in the distributor

17

Pertronix. No condenser.

18

Not familiar with Series 2, but could the fuel tank not be venting properly?

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19

Had that problem too with the gas tank was not venting too
It would for run for a few minutes and stop
When i went to unscrew off the cap a big whoosh of air was sucked jin
I ended up drilling a 1/16” hole on the cap

20

Dave,
I had a similar stalling problem caused by fuel starvation in my 1969 E-Type FHC (original 4.2L XK engine and original Lucas ignition) after I purchased it about 20 years ago. Several times after driving a variable short distance the engine would stumble and then die only to start up easily after a short wait by the side of the road. One time after this happened I removed the fuel filler cap and was surprised by a loud “whoosh” as the tank vented.
It seems that the prior owner polished the fuel filler cap with metal polish in preparation for the sale and inadvertently clogged up the small vent hole in the fuel filler cap (shown circled in red in the attached picture) with dried metal polish.

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I conclusively proved this was the problem by driving the car home with the fuel cap loose and the engine did not stall. Then I cleaned out the fuel filler cap vent hole with a small drill bit rolled between my fingers allowing the fuel tank to vent properly and this permanently fixed the fuel starvation problem.
I hope your problem can be fixed as easily. BTW, the emissions control systems changed during Series II production so your car may be configured differently and/or a prior owner may have mucked things up by modifying emissions or other systems in your car. There are lots of post on this list about various kinds of Pertronix ignition system gremlins that have caused engine stalling problems like you have encountered. Good luck.

Paul

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