The Stovebolt Site Forums The Shop Area The Electrical Bay Stomp starter puzzlement

1957 3100. 235. Stomp starter. 12v
Truck has just recently been hard to start. Battery at 12.6 +/-
This stomp starter has a small terminal just below the large connector for the battery cable. (I have been told that different configurations exist)
It is my understanding that this small connector/wire (purple btw) is connected to the ignition switch to provide 12v at the coil only during the time when the stomp starter is engaged.
Correct so far?
Then when the starter is inactive, the coil is fed through the firewall mounted resistor and runs at about 9.6v +/-.
Correct?
Disconnecting the purple wire from the starter but leaving the large battery cable attached and checking voltage....
12.6 at the large lug on the starter.
10v +/- at the small terminal on the starter with no wires attached and with the starter engaged.
Shouldn't the voltage at the small terminal be 12.6?
Your wisdom is appreciated.

With the starter engaged, voltage will be down a bit, because of the load on the battery from the starter, although 10V seems a little low. It's also possible that there's some crud or pitting on the connection to the small terminal inside the switch that causes a voltage drop. I would start by cleaning up the cable connections at the battery, frame ground, engine ground, and starter, and see if things improve. You can also track down a bad connection by comparing voltages (under load) between say battery post itself and the cable clamp, and do that down the line toward the starter.

Kevin,
Thanks!
New battery, new cables, new connectors....I just have not gotten into the starter switch itself. I guess that is next. I was kinda dreading it looking for some magic. Yeah I know...patience is a virtue. George

Kevin, Do you have any idea you getting from that terminal on your stomp starter? Thanks!

Expanding on what Kevin said ...


Not exactly. The purple wire connects the 12v battery + lead at the stomp switch to the coil + terminal while the stomp is pushed. Provides battery voltage to coil + during starting.


Yes, correct. If you test coil + to ground with the key on and the engine NOT running you should read battery voltage if the points are open and around 8 volts if the points are closed. If the engine is running and you are using an old analog meter (that has a needle pointer) you'll probably read somewhere around 9.5 volts. A more modern digital meter will bounce around all over the place, especially at low engine speeds.


Yes it should, BUT did you check the "large lug on the starter" with the "starter engaged"?? If not, try again measuring the large lug to ground while the starter is operating. Leave the purple wire connected on both ends, but remove the high voltage coil to distributor wire to keep the engine from starting. Also, make sure your + meter lead is touching the "lug" on the starter switch that the battery cable is attached to, not the nut or the cable.

Can't help you there, because I'm running stock 6 Volts on my 1951. My stomp starter switch doesn't have that smaller terminal.

May have already been stated. Take he starter button cover off. Watch where the plastic insulators fall! Clean the copper post and bottom of the button. Had a similar problem starting. Mine had carbon buildup.

1. As said clean the copper lug part of starter. If it's worn down or worn at an angle, there are replacement lugs.
2. Clean the copper piece(s) that engage the side terminal.
3. The side terminal may be just like if you had the headlights on, it's "dimming" due to starter taking amps and volts.
4. You don't know and we don't know if the "hard start" has anything to do with the stomp switch. 10V should fire the motor. But you don't describe "hard start".

It does start but not right away
No fire at all
Some fire
Slow crank
Pops/sputters out of carb or exhaust backfire
And as said we don't know battery voltage while cranking. Could very well be a bad battery breaking down. But again, specifically describe "hard start".
Don't want to assume anything yet and start chasing the wrong thing. Hang loose til we get info, think and advise tests.

As far as the battery is concerned, I remember what someone told me. "Volts don't start a truck. Amps do." Is that a good thing to remember? Or BS?

Sorta true. But volts drive the amps down the wires. And resistance anywhere in the circuit impedes the delivery of the amps.

Power = Volts x Amps, and power is really what turns the starter. So you really need both volts AND amps to get the job done.

As Kevin says.

Need both. Both start the motor. As the starter cranks and draws amps, the voltage necessary to push the amps goes down becasue of voltage drop inside battery as it heats up. Heat equals resistance. Other voltage drops/resistance in play also. Then not enough volts to push amps to start motors with some kind of problem.

To start a good running motor with proper cables (and good foot start contacts), In a pinch, a starter needs 300 min amps at 10V min. Carb motor, non electric fuel pump. The points can run on 8.5V-9V.
But still waiting for symptom explanation from poster.