While I might consider myself an old-timer, I need the advice of real old-timer who regularly works on this stuff! I haven't troubleshot a points system in 30 years. As simple as this system is, I am frustrated as I am totally stumped! This is on a 64 Ford F100. All ignition parts, including the distributor, are one year old with a few hundred miles. The coil is original. It ran perfect up until now. It's a very intermittent problem. One minute it will run fine, the next, barely. At first I thought it was a fuel problem as the exhaust smell was rich and the plugs were extremely sooty. I found no dirt in the bowl and the needle and seat looked good. Float level was checked and float is not sinking; couldn’t hear any gas inside. As bad as it’s running I believe I should see some black smoke but it looks clean, just rich smelling. I now figure it’s because with no consistent ignition, gas is not being burned and feathering the gas to try to keep it running is just adding more fuel. I connected a timing light to the coil wire. The flashes are very intermittent. When it does run normal, I can see a miss every now and then. Here is what I have done: Checked coil resistance. Primary: 1.8ohms, Secondary: 7.5Kohms. The new coil is 1.5ohms and 12.3Kohms. Checked voltage at positive coil terminal with the points closed: About 7V. Seemed a little low to me so I connected battery voltage at the coil, still misses. Connected test light at the coil neg term and ground. While cranking, the light flashed as the points open and closed. Looked for carbon tracks and cracks inside cap. Keep in mind that after every successful check/measurement, I would start the engine to see if I still had the problem. One thing that puzzles me: I don't always get a spark at the plug wire when I manually open the points. To byp*** the points I ground and unground the negative coil terminal. Sometimes I get spark at plug all the time, sometimes not. This tells me it could be the coil so I tried a new one, same result. When I manually open the points I get a very small spark across the contacts. If I disconnect the condenser I get the same size spark. Normal? Tried new points and condenser, same result. As a last chance at possible flooding, wouldn’t I still get a timing light flash even if the plugs weren’t firing? This is long enough. Please ask questions if you think you can help. Thank you!
You seem to be very knowledgeable and thorough. I hate when these normally simple things make me crazy. I chased a gremlin similar to this and it turned out to be the wire from the distributor to the coil. Had a break inside the insulation. You couldn't see it and it was intermittent. I might not be any help but I am willing to drink on your behalf just in case you dont drimk.
Here's a refresher course on points type ignition systems that might help keep you on the right track. https://www.jalopyjournal.com/forum/threads/hot-rod-technical-library-basic-ignition-systems.983424/
Check for oil or fine grit inside the distributor. I chased a problem like that and it turned out to be oil in the area around the points. Also check for play in the distributor cam. Try to shake it back and forth, if it moves much the bushing is bad and will give you erratic spark. Also try another condenser, even if you have replaced it once, lots of bad new ones out there. Report back when you find the cause. Good luck. Brian
Agreed on the condenser. They are junk. Points and condenser work fine as a rule in general, however this is not the case with the ersatz Scheiße sold today in the auto parts stores today. Grab an old condenser from your junkbox and try that. If you don't already have a Ford Shop Manual, get one, and/or maybe a MoToRs Repair Manual. They have step by step troubleshooting that helps narrow things down through process of dividing things in two or isolation and elimination. Most of us don't work with the obsolete tech often enough to really stay on top of our game, especially on the stubborn problems.
This sounds like a wire issue. The first place I would look is the two coil connections. The rubber L shaped boots tend to have broken or nearly broken wires at the base of the boot. Check that out. If OK.... It's a matter of chasing wire all through the whole system checking for breaks and poor connections.
One common problem on Ford's is the breaker plate wearing. You can set the points and as soon as you fire it up and the vacuum advance pulls in, it throws the dwell off. Some times it will start to die, vacuum goes away and all of a sudden... It will start running again. Disconnect the vacuum advance and see if it smooths out. You can watch it happening on a dwell meter too, the dwell changes.
Is it a 6 cyl or V8? If a six it has the wonderful lodamatic distributor......which has it's own set of issues.
I recently did a tuneup on a old cornbinder. Brand new points and condenser and it fired right up. Then I could only get spark to the points but nothing at the plugs. I only started the truck one time and the condenser failed. I switched the condenser with another old engine sitting in a shed and she fired right up again. You said fire at points and intermittent fire to plugs ... I would double check the connections and maybe try another condenser.
To add to what greybeard is saying, the way the breaker plate is designed, it gets pulled by the vacuum advance in a arc that causes the dwell to change, even when new.
X 3 on the condensor. The new stuff you buy is junk. I've chased my tail for weeks, and it ended up to be bad condensors, 3 in a row. I am now on the lookout for NORS points and condensors to fit my junk.
Check the lead wire to the points in side the cap. Ohm meter on both ends and wiggle it. I have had them break inside the insulation before. Does it have a ground wire to the breaker plate like a SBC does? D
Check and clean your grounds and also the resistor and its connections. 7V at the coil is low. Should be 8-9V? I had similar problems and it turned out to be both bad engine to firewall ground and loose connections inside the resistor. I have since soldered the rivets in the original resistor. Also, its been mentioned on here, the insulation on the points wire can wear and ground where it goes through the distributor.
Wow, lots of responses on this one! I'll try to address each one. Sorry for the length… HAHA! Thanks for the offer! The wires are new, about a year, but I did measure them. 2.5K to about 4.5K depending on the length. They were pretty much consistent in length vs resistance. Awesome! Love to read period articles compared to the modern interpretations. (You know how a story can change over the years.) The distributor is clean. No side play either. Tried another new condenser but it didn’t fit physically so I couldn’t run it installed. Just m****ly operated the points. No difference. I’m all for reading up on this stuff if I can find a manual. The negative wire is new. Haven’t come up with any intermittent connection issues yet. I connected battery voltage to the positive terminal and it still ran bad intermittently. New distributor, but I will try disconnecting the advance hose. Already dealt with that when I started working on it. Replaced the distributor with a 67 and up. There’s another vote for the condenser… I’ll put a dwell meter on it. One more condenser vote… Brand new wire. Can still check it though… Yes, there is a wire from the points to the plate. Thought about it. Need to see what’s involved. If it’s as easy as a GM HEI, it would definitely be a thought. I thought that was low too but connecting battery voltage to the coil doesn't help. Also checked grounds between dist and block to battery, etc. Every combination/connection I could think of. OK, now for some specific questions… I know the condenser is used to reduce arcing on the points but will the engine run without one? Visually, the points arc slightly with or without the condenser. Seems like it’s not having any effect on the circuit. I measured it with my Fluke meter at .2MFD. A little research seems to show this is about right although I read that it’s better to test it at a higher voltage to help reveal problems. Does a timing light make a good tool for monitoring spark activity? I noticed that if the plug wire terminal is not allowed to arc to ground the light will not flash. I’m asking this because if it’s not flashing it may not necessarily mean the ignition system is not supplying voltage to the plugs. It might be not firing because of lack of path to ground. That’s another reason I wonder if it really is the carburetor running too rich and fowling the plugs. The plugs were very sooty but after gl*** beading them they are staying clean in the small amount of time it’s been running. I can’t smell fuel on them. The throttle plates are wet when it’s running but I also don’t see excessive amounts of fuel dropping into the venturis. I think wet plates are normal. I need to do a comparison check of the amount of fuel I can see when it’s running good and running bad. I’d still like to know why the plug doesn’t hardly ever fire when I manually connect and disconnect the coil’s negative terminal to ground. Could my timing light and this manual test might not be a good way to troubleshoot? Nothing I have found has been conclusive enough to allow me to focus on fuel or ignition!
the points and condessor are ground to the diet housing which is ground to the block , pull the diet and clean the bottom and block where it touches
I figure that would serve the same purpose as the timing light, wouldn't it? I checked the continuity between the distributor and block. It checked good.
I'll answer a couple of your specific questions. 1. First, the engine will not run without the condenser. It is required in the circuit in order to provide a path to ground for the collapsing field current in the coil. 2. It sounds like you have an inductive clip on your timing light, that clamps around the plug wire. The inductive clip has to see a magnetic field which is generated when the current that fires the plug goes to ground. If the plug wire does not arc to ground there is no current flow, so it will not trigger your timing light. 3. When you manually connect/disconnect the negative coil terminal to ground, you are attempting to mimic the function of the points. Keep in mind that you have removed the condenser from the circuit when you do this. If you have a condenser connected directly to the negative coil terminal, and have the body of the condenser grounded, then manually connect/disconnect a ground to the negative terminal you should see a consistent spark from the high voltage tower of the coil.
Ok, but this is a common error heard often when talking about automotive electrics. "Continuity" is (practically speaking) meaningless, because it doesn't tell you anything about the ability to carry current. You could check for ohms resistance. This won't provide any meaningful information either. Good check on the condenser, but you're right, they need to be tested at rated voltage, and after they are good and hot as well, to be an accurate test. Think of the condenser as like a shock absorber for the ignition system. It helps ensure that all of the spark energy is directed to the plug and not wasted as arcing across the contact point gap. I didn't believe it is possible for an engine to run without a condenser, but a few have claimed to have seen it and have no reason to doubt them. It won't run very well.
Because when electronics fail, you are SOL. When it wont start, you can pop off the dist cap and check points for fire. You can reset points by eye good enough to get home to a feeler gauge. (happened to me last week) When the alternator fails, your electronics fail. With points you keep driving even hundreds of miles on the battery and the new battery you buy on the trip. Seen that on my brothers and my sons car. Sure electronics are 'better' except when they arent.
1. I was hoping that running it without the condenser would give me an indication if it's working or not. My theory was if it was failing open then it would be like no condenser is installed and it would run the same way with or without. If it was shorting out then it would run better without it. BUT, I am also getting inconsistent spark when manually operating the points. I need to reverify that. 2. I did some experimenting and my results were consistent with your explanation of the need for a complete circuit of the secondary side to produce a field for the light to trigger. That's one reason I'm not sure my method of using a timing light is sound. If, say the plugs are flooded, then they won't fire thereby not producing a flash. So, just because the light is not consistently flashing it doesn't mean the ignition isn't operating. That's why I wonder if I am chasing my tail when it could be the fuel system. I'm just not totally convinced yet. 3. Didn't think about the condenser not being in the circuit when I was trying to manually trigger the coil! True. Put a load on a circuit that shows good continuity and it falls flat on its face. Thanks for everyone's help! I think I'm at the right place here!
Quick update: Of course, I don't a get flash from the timing light when I manually operate the points is because the cap is off! Duh... Doesn't even start without the condenser. (As Ebbspeed said) Ran a ground from the battery to the distributor, no change. (Thanks xix32) Fuel dribbles into the venturi when above idle. Dry at idle. Identical when engine is missing. Fuel system is exonerated as far as I'm concerned. Engine has been running for several minutes with just a few moments of missing. I managed to get those checks in during that time of missing. I have new condenser I am going to connect externally as it won't bolt up to the breaker plate. See what happens...
I drove from Cleveland Ohio to Dayton Ohio with electronic ing with the alt not working. Change the battery in Columbus. Any in system can fail I have run single points, dual points, mag, and electronic. They all get the job done some better than others.
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