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General Tech Voltage Drop and Starting Problems

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Wow, talk about frustrating. I had a similarly hard to diagnose issue 6 years ago. Started has a misfire only when hot and under heavy load. Progressively got worse over several months where it misfired when hot, then warm, then all the time. Finally died and left me stranded one mile from home.

Not sure how but finally diagnosed it as a failure of the low tension lead from coil to dizzy (no. 52 in Moss catalogue). Vibration had caused the strands of wire at the female connector to slowly but surely fail. Heat apparently exacerbated the problem.

$-0- repair once diagnosed. Cut off old connector, crimped on new one. Soldered it and used heat shrink tubing to give it some structural integrity.

If this is your issue, I bet when replacing cap, points, condenser yesterday you unknowingly moved the wire temporarily restoring integrity to the connection.

Easy to check and rule out. Even more frustrating if all this was due to a $1.89 piece of wire.

Good luck

Bob
KVH said:
This evening I just about gave up on this car. No matter what I tried, the car wouldn’t start and the spark seemed unusually weak using the old “screwdriver 1/4 inch from ground” method.

I decided to stop in at the local Moss dealer and shop, and I bought a new distributor cap, points and condenser. The engine started right up and runs perfectly now.

This is so frustrating because I put new points and condenser in just a little over a month ago, and I have two old distributor caps that I switched out and none of them made any difference.

I can’t quite even begin to figure out the problem, but I have a few suspicions.

One suspicion is that there are manufacture defects in the distributor caps, and that I finally have one that is correct. Another is that condensers are regularly defective, new or not, but I can’t imagine that a bad condenser would cause me to stall and then also prevent me even from restarting the vehicle. My third suspicion is one I’m actually considering seriously.

It’s this: My Moss Cobalt brand plug wires look great, but fit very tight, and I often have trouble feeling the snap at the back of the spark plug. I’m wondering if this intermittent problem I’m having with my engine stalling, and then not starting, is caused by a plug wire slipping off the spark plug inside the boot.

In any event, as far as I’m concerned, the mystery continues despite my presently perfectly running engine.
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My points use that new MGB type clip for the condenser. No more insulated nylon ring and tiny nut on pole. The coil wire and condenser wire are tied together, and then slid into the points frame where a clip is fabricated. Weird but OK. But to test another condenser is a hassle unless I order the whole piece—HT wire, condenser, etc. I’m wondering about the approx ten extra condensers sitting in my shop. Would it be a sacrilege if I just cut the wire on the new setup and soldered and heat shrinked an old/new condenser in place of the new ones, maybe just as a test. I’m just saying the old condensers attach differently, but I could see finagling one onto that clip in the new points setup. Hope I’m making sense.
 
Here is a pic to clarify my question. It would be a shame if I couldn’t use any of my old style (unused) condensers. As you can see, the new one for my distributor is a package deal with the wire to the distributor. But I guess I could cut and solder. Or, jam that o-ring connector into that same clip on the points rail. Doesn’t seem it would be all that secure.
 

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And, stating the obvious, based upon the stalls and non-starts over the last six months, all in the same vehicle, if the problem was, in fact, the condensers, that would mean that in each case it was the condenser from this new point set up (attached and soldered to the distributor lead), which, as I am told, is the latest issue for MGB vehicles, adapted to Triumphs.
 
I second the input from Bob in #21. Replace the white wire between the coil and distributor. When I replaced mine I was given the following advice.
Make the wire long enough to allow at least 2 coils. ( This wire apparently gets a lot of flexing) . Soldering is also preferred.
Charley
 
That wire was among the first things checked. It was fine. Continuity and 0 resistance. It was essentially new since it came with the points as I set out above. I also ran the coil and distributor voltage tests with points open and closed, and the results were to spec. The original 1 volt drop at the coil went away as I tested more. I’m baffled.

All condensers I checked hold a charge and gradually discharge. Even my old style condensers react exactly the same way. But I need to explore this further as I’m reading material saying my ohm readings should rise fast and materially, to “infinite,” and I’m definitely not seeing anything like that. Maybe I need a better multimeter. I’m truly at a loss comparing all the literature and YouTubes on condensers, and I’m inclined to believe the old Triumph “fault” manual that says there is no effective way to test a condenser other than replacement.

Who knows . . . . I’ll keep chasing this issue down until I know I’ve got answers.
 
You can't test an ignition capacitor in any meaningful way with a multimeter. That's clear. They operate at high current and voltage, much higher than what a multimeter uses. Here's the result of my study into the cause of capacitor failure: https://sprite.nonlintec.com/cap_failure/. I think you'll find it eye-opening.
 
There are condenser testers in some multi-meters...but it is not a common feature. I also have several Tektronic testers that check condensers...or rather capacitors, which are the same thing. Even then, I do not always trust the results. Auto condensers are subject to extreme heat and vibration that can't be duplicated during testing. I figure there are 2 failure modes for a condenser:

First is if the internals short, essentially making it a short circuit from the case to the center post. This would never allow the coil primary wire to open, so it never collapses it's magnetic field. Of course the short may not be complete, in which case the engine will run, but the coil will not generate full strength, since most of the energy is being taken by the shorted condenser.

The second failure mode would be open circuit. In this case it would be like not having a condenser at all. The engine would run great...for a short time, but every time the points open, the collapsing magnetic field at the coil will back feed the points with hundreds...or even thousands of volts...which jump the point gap every time it opens. In short order this high voltage spark will burn the face of the points, so they no longer make a good contact when closed. The end result is a car that starts running poorly and gets worse until it will not run at all.

All I can say about your 10 condensers is...they are really cheap. Toss them if you have any doubts. It's not worth the frustration for $3-5 a pop.
 
I was out on the road. It did it again. I just got done being towed back to my house. This is the third tow in nine months.

I know there’s no need to summarize, but I have a new condenser new points, new coil, new distributor cap and a new rotor.

My point gap is .015 and my timing is right at 4° before top dead center.

The car was running great as I had reported a day or two ago. But it was hot outside, and the car got hot, and then everything just petered out. I was very fortunate to get off the road. I can’t tell you how lucky I was to be able to pull around a corner and get into a parking lot. The behavior of the car is that it just quits.

I have a new fuel pump and I tested the pressure. It seems adequate. The fuel pump bowl is full of gasoline and the float chambers are at the proper level. My spark plugs look perfect.

Don’t I need to start looking elsewhere? Pull the head and look for burned valves? Run a compression test? I’m thinking of how great the car was running. This problem just comes on so suddenly and erratically.

I’ve checked for loose wires at the ignition switch, at the solenoid, and even at the voltage regulator. I didn’t find any issues.

Imagine me ever telling anyone I’ve been tinkering with these cars since 1971. You would think I would’ve encountered every imaginable fault. I guess not.
 
KVH said:
I was out on the road. It did it again. I just got done being towed back to my house. This is the third tow in nine months.

I know there’s no need to summarize, but I have a new condenser new points, new coil, new distributor cap and a new rotor.

My point gap is .015 and my timing is right at 4° before top dead center.

The car was running great as I had reported a day or two ago. But it was hot outside, and the car got hot, and then everything just petered out. I was very fortunate to get off the road. I can’t tell you how lucky I was to be able to pull around a corner and get into a parking lot. The behavior of the car is that it just quits.

I have a new fuel pump and I tested the pressure. It seems adequate. The fuel pump bowl is full of gasoline and the float chambers are at the proper level. My spark plugs look perfect.

Don’t I need to start looking elsewhere? Pull the head and look for burned valves? Run a compression test? I’m thinking of how great the car was running. This problem just comes on so suddenly and erratically.

I’ve checked for loose wires at the ignition switch, at the solenoid, and even at the voltage regulator. I didn’t find any issues.

Imagine me ever telling anyone I’ve been tinkering with these cars since 1971. You would think I would’ve encountered every imaginable fault. I guess not.
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Does it feel like you turned the key off?

Or does it start missing and then die?

Charley
 
Misses, chugs, sputters and dies. I’m digging in again. I’ll report if I learn anything useful.
 
That sounds fuel related...that's the way an engine acts when the carbs have run out of gas or on the opposite end of the spectrum, the carbs flood with gas.
 
poolboy said:
That sounds fuel related...that's the way an engine acts when the carbs have run out of gas or on the opposite end of the spectrum, the carbs flood with gas.
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Agree with the above. And as it does not just die, it does not sound like ignition.
Have you checked your fuel tank for contamination?
Note that you can not just look at the fuel bowl for an indicator of fuel supply. As fuel drops into that bowl and goes out the top.
Checking inside your float bowls when the car dies is your indicator.
Charley
 
Guys, I’ve overlooked something glaring. It’s 105 degrees here, and I go driving right in the peak of it. I just do.

The fuel is getting hot. I see it bubbling in the fuel filter. I have many sources of heat: My dual mufflers span outward and one pipe is within an inch of the fuel line for several inches, and within five inches for another foot.

On top of that, the glass fuel bowl on the fuel pump gets extremely hot next to the engine, and the plastic fuel filter up near the carburetors gets equally hot. From what I am reading, these heat sources would be sufficient to begin vaporizing my gasoline inside the fuel lines, and this would explain the great difficulty I have restarting the car after turning the ignition off.

I know it sounds like a rationalization, but once I stop the car and fresh fuel is not running through the line, the fuel that is in the line is probably boiling at an even faster pace.

All of this would explain why nothing that I do makes any difference. Tuning, timing, fuel mixture adjustments, ignition details – – nothing matters. As several of you are saying, it probably is fuel after all.

I’m going to focus on heat shields, foil and heat shielding tape. I may even run over to a muffler shop and see if my exhaust pipes can be reshaped.

Now, this does leave me puzzled why the car wouldn’t start even three and five hours after first cutting out. That should’ve been long enough for the fuel to cool. In addition, my car wouldn’t start a couple of mornings ago, after it sat all night long. This also seems difficult to explain if the issue is vapor lock or boiling.

Sorry for the opera. I do value all the input. Any further thoughts would be appreciated.

(PS last night, a full nine hours after my car stalled, it still would not restart. I was sitting thinking about all this, but before even considering the vapor lock and high heat issue, I decided to yank my distributor, the relatively new one referred to by Moss as a “Race Distributor,“ and I put my 20 year old old dizzy back in. The car started right up instantly. I’m going to chalk this up as another coincidence, because I can’t imagine that there’s really anything defective in my “new“ Race Distributor,” and I certainly was unable to notice anything upon inspection. I think I need to move on and explore this “bubbling in my fuel line“ problem.)
 
This is a doozy. I am still on the fence if your issue is fuel or ignition. The fact that it still would not start after 9 hours of cooling but started as soon as you swapped dizzy makes me still think it is ignition related. If it happens again after 9 hours of cooling, I'd be tempted to give a bit shot of starting fluid into the air cleaners and see if she fires.

Been down the road of fuel vapor lock (in the fuel lines - leads to fuel starvation) and percolation (in the float bowls - leads to overly rich mixture) before. If the float bowls are purcolating, you will get a heavy gasoline smell uner the hood - this was me. For me, it only happens in very high ambient temps when idling a long time at a stop light, in stop & go traffic or if I shut down and try to restart w/i 15 mins. But, neither should impact you when driving at speed (with lots of air coming in the front end and fuel constantly moving through the lines).

In Connecticut, this happens to me maybe once every other summer. Did not want to go the route of full carb shields. So, I removed my plastic fuel filter and wrapped the fuel line from pump to carbs in heat reflective wrap. I also bought some float bowl koozies from Joe Curto (photo attached) - not on his website, had to call him. I don't think today's E10 fuel helps either. My car idles at 650 RPM so now, when stuck in slow traffic, I will pop the hood to allow some ventilation to the engine compartment and pull the choke ever so slightly to raise the fast idle to 1000 or 1200 (but not to the point the choke engages). This does three things: 1) speeds up waterpump, 2) moves more air via engine driven fan, 3) keeps new/cooler fuel moving through the lines

Last, I am still looking at where my ignition timing is set and possibly having my distributor and vac advance unit rebuilt. I am pretty sure I am at 4* BTDC and my vac advance is not working right. If not advanced enough, unburned fuel will exit into the exhaust manifold on the exhaust stroke - driving up exhaust manifold temps and, thus, underhood temps.

Keep us posted.

Bob
 

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I once had a problem of my car dying at odd times...and sometimes it would fire right back up and others not. It turned out to be the ignition switch.

These are very simple cars. Next time it dies, try a hot wire from the battery to the coil...that will eliminate all the wiring, switches, regulators, fuses and wiring. If that does not get you running, then you have it narrowed to the coil and distributor.

I would not discount vapor lock, but vapor lock does not normally kill you instantly. You usually get some sputtering, and even when trying to start it will normally pop every so often. Add that to the fact it would not restart for many hours, and vapor lock should be down the list for now...that is so long as you are positive the fuel pump is working??
 
When you replaced the distributor and the car started working, that's very strong evidence that the problem is electrical, not fuel. Why not just accept that, instead of writing it off as a coincidence?

When you replaced the distributor, you probably disturbed the part that has an intermittent failure. It's really common in these cars.

The fuel boiling is a separate issue. When I had my Bugeye Sprite, I solved this problem by rerouting the fuel lines so they sloped continuously upward. Then, fuel bubbles would simply rise to the top and vent through the float bowl vents. > Bugeye Sprite Fuel System Modifications <
 
I have a slightly modified cam for greater power at high RPMs. I didn’t put it in. The prior owner did. I have the specs hidden somewhere, but I remember him saying that he only curved it a bit. I added a race distributor, thinking it would complement the cam. It optimizes spark timing for power mainly at mid-to-high RPMs. I’m no expert, and grasping at straws, I just decided to pull it and install my original stock distributor.

I suspect that the problem is a mix of items and that I am getting closer by trial and error. Today I’m installing an electric fan and I’m adding heat shield material at the fuel pump and fuel filter. I also reinstalled an old ARE heat shield for the carburetors.

As an aside, I might mention that a little over a month ago I replaced the fuel bowl needles with stainless steel (brass?) ones having that tiny spring button at the bottom and no viton tip. I was concerned that the viton might more likely cause a sticking problem, and I felt more comfortable going back to the straight old-fashioned steel tipped needles.

I’ll report more as I learn.
 
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