The Stovebolt Site Forums The Shop Area The Electrical Bay Ignition Coil

My '53 3100 runs fine at idle, but only goes a couple miles before quiting on me. After sitting for 20-30 minutes, I can go another couple miles. Trying to exclude problems....if my 6V coil measures 1.5 volts across the primary, does that mean it's good or do I need to do further testing? In addition, I noticed that the coil box says...No external resistor needed....I DO have an ignition resistor. Do I need to take the resistor out?

The primary winding resistance should be measured in ohms, not volts. 1.5 to 2 OHMS sounds about right. A voltmeter reading will change, depending on whether the engine is running or not, and whether the points are open or closed on a stopped engine. With the engine running on a resistor-equipped coil, the voltage from the coil + terminal to ground should read about 9-9.5 volts. Engine stopped, points open, ignition switch on, both + and - terminals will read battery voltage. Engine stopped, points closed, ignition on, the + terminal will read about 9V, and the - terminal will read 0 V or very close to it. Any engine-stopped reading at the - terminal above about .25 volts or so with the points closed indicates dirty or burned points.
Jerry

Edit: OOPS! Just re-read your post. 6V systems DO NOT need a resistor. Take it out. When the engine quits, do you have spark? If not, try changing the condensor. They can heat up and short out like a closed-up set of points. That's a VERY rare problem, though!
Jerry

Sounds like crud in the fuel system maybe.

The fuel system is next on my radar to diagnose.....

I'm new to the 6v/12v stuff......I currently have a 12v battery and an alternator....do I need a 12v coil and no resistor or do I need a 6v coil and no resistor...or vice versa....I'm confused....I think.

The coil voltage needs to match the battery. By using the 6 volt coil on 12, even with a resistor, you're roasting the points. Change out the points and condenser, get a "12 volt" coil that requires a resistor, and wire things up according to a 55-up wiring diagram with the resistor in the circuit from the ignition switch to the coil. Use a bypass wire from the starter solenoid "S" terminal to the + side of the coil if you 're running a key-type start, or a 55-62 year stomp starter switch with an extra terminal for resistor bypass if you're using a 6 cylinder engine with a stomp starter.

Jerry

I have a floor starter....explain this further.

You need a switch like this. Run a wire from the side terminal to your coil in addition to the wire from the resistor to the coil. This switch will supply 12V to the coil for starting.

To the + side of the coil, right.....what gauge wire do I need to use?

14 or 16 gauge will be plenty- - - -there's very low current in the primary ignition circuit, less than 5 amps. Since the battery voltage can drop to just above 9 volts during cranking, the bypass wire allows the coil to get enough voltage to maintain a hot spark with the starter running. Otherwise, the resistor would reduce the voltage applied to the coil to 6 or 7 volts, not enough to get a good spark. As soon as the starter switch disengages, the resistor goes back to protecting the points from excessive primary current.
Jerry

Got all my parts in yesterday and this morning was able to replace and rewire everything that was suggested.....I will be road testing late this afternoon after work....standby for results...thanks in advance.

I still have the same problem after replacing coil, condenser and points.....

My '53 3100 runs fine at idle, but only goes a couple miles before quiting on me. After sitting for 20-30 minutes, I can go another couple miles.

don't see any mention of what engine has the problem eightfan .... nor any mention of the time it'll run or at what speed? will it sit still and idle all day? is it well warmed up before the "couple miles"? "couple miles" means what? do you check any thing when it dies or just fidget for 20-30 minutes and try again? when it does restart, does it fire right up or require a period of cranking?

more likely fuel than ignition, maybe a temperature caused problem, maybe crud from the tank plugging the line [have a fuel filter?], or just a bad fuel pump - when it quits, immediately check for fuel in the carb [accelerator pump] as well as spark

Bill

Let's see if I can get you some answers.....

Engine--original 216

Will sit and idle all day without a hickup.

Will run at about 40 mph for 1 to 2 miles before missing then quiting.

Have the same problem whether engine is well warmed up or cold.

I just fidget for 20-30 minutes.

When it restarts, it requires a period of cranking with carb at full choke.

I have a fuel filter between tank and pump and one between pump and carb.

I have not checked for fuel in carb or spark when I have the problem.

Thanks for any additional help.

by not doing any immediate roadside trouble shooting, you're wasting money with random parts replacement, the long cranking time and choke say fuel problem, nothing to do with ignition

I'd bet your tank is dirty and the line is plugging someplace from the driving movements and letting the float bowl get empty, might be right at the carb float needle .... some think a filter between tank and pump is a good idea, I think they're trouble, take it out and replace it with a piece of tubing - next time it happens immediately look at the filter between the pump and carb and see if has fuel in it [if it's not the glass bowl OEM style or a see-thru plastic type change it to one] or have bit of gas with you and immediately dump some in the carb and see if it starts - I'm betting it will, although it might not stay running long depending on where the plug is, could be the sock in your tank

Bill

My old lady told me the same thing or at least the wasting money part. Why get rid of the filter before the pump?....seems like the more the merrier. What do you mean by..."could be the sock in your tank"? I'm thinking your right about the dirty tank. Do you have any tips on cleaning, etc. Can the fuel pump have an intermittent problem or is it either 100% or 0%? I took the top off of the pump and noticed that the diaphram has a stretched appearance. I will trouble shoot as you suggested on my next road test....thanks.

The sock probably refers to a sock-like piece/filter connected to the end of the fuel pick-up in the fuel tank. Was the sock a standard part in a 1953 truck?

ahh fergot, AD's don't have the fuel pickup tube on the sender, no sock, I guess that's why some folks like filters before the pump .... I don't like them there because pumps are gravity feed, they don't suck as well as they blow, easier to get a fuel delivery problem and the filter isn't real visible, easy to forget to check it- the factory position is easily visible and sufficient if checked regular, ANY flakes in it indicate potential trouble, doesn't help to have more filters if what you need is a new tank before it starts leaking

one way to check the tank is drain it at least a bit and see if there's any solids showing - with the under seat tank you might get an idea of condition thru the sender hole, rusty tanks aren't unusual in these ol trucks and large flakes can plug the outlet enough to slow fuel delivery just like a forgotten dirty filter

fuel pumps usually work or not, although they can get weak from a worn lever so it doesn't provide full stroke, or if the flow is restricted [especially on the inlet side] they might not provide full pressure - possible cause, but less likely than junk in the line

Bill

I think I have a couple of problems....the dirty tank is very likely. Could someone please explain, in detail, how the fuel gets from the entry point at the carb to the cylinder. I have a newly rebuilt Rochester type B with manual choke.

When I manually operate the accelerator pump, should I see gas fumes or a stream of fuel? Currently, I see fumes.

Right now, it will crank (choked), but dies after about 10 seconds. When I pour fuel in the carb it will crank (choked) and die after about 10 seconds.

carb manual ... when you look in the carb and pump, you should see a shot of liquid gas - the accelerator pump is for an extra shot under first load, otherwise generally speaking, the fuel route in is via jets that meter the flow depending on engine vacuum and throttle position, but requires the float bowl to be filled, which is controlled by the float opening and closing the inlet with a needle valve

starting and dying quickly probably means no fuel in the bowl, pop the top and look, might be a plugged inlet or stuck needle - and while it's open see if the accelerator pump looks deteriorated - if the carb hasn't had any attention in a long while, will be worth the time and few bucks rebuilding it

another check of the system is to remove the line at the carb inlet, poke it in a container and crank the engine to see if the pump is moving fuel well

Bill

OK.....The tank is out and it is very rusty and needs help....tips on cleaning it?

got any rad shops nearby? some of them will hot tank it and coat it inside and out - or you could try the coating job yourself, Eastwood sells kits for it - or you could buy a new tank from one of the vendors

Bill