1938 Dodge Truck Starting Issues

I have restored a 1938 Dodge 1/2 ton truck and just recently it will not always start. It has been running nicely for the last couple of years and been very reliable and quick to start hot or cold. It has the original 6 V positive ground system.

One day I was driving and it lost power at the higher rpm. I got it home and then couldn't get it started. It seems to be getting gas just fine. I messed around with the ignition, not finding a problem and changing nothing really and was able to get it started again and once running, it is great - smooth idle, no hesitation, good power - absolutely no operational issues. But then the next morning, it will not start.

When it is not starting, there seems to be no spark (as observed by grounding a plug to the head). I have checked that there is 6V at the negative coil terminal when the ignition switch is on, continuity of the wire from the positive coil terminal to the distributor, cleaned and regapped the points, tried two other coils but I can find no issues. It seems to have a mind of it's own - once was checking the spark with #2 plug out and for no known reason, it suddenly had spark and started!

So, what could cause a perfectly fine running engine to have these intermittent ignition problems?

Tom

 

Try a hot wire from another battery. You could have a leak somewhere and not enough juice for starting and ignition. Check everything with an ohm meter too. A friend's Buick has an insolation problem where the wire went through the distributor. The insolator had some rust on it and had an intermittant miss because of it.

 

Agreed with noboD. 6 volt ignition systems are very sensitive to bad /weak connections.

 

OK, I thought I found it because the fuel gauge is powered off the ignition switch and I have some issues with that so I disconnected the fuel gauge but still not spark. I get less than 1 Ohm from the tab going into the distributor to ground when the points are closed and it is open when the points are open. I get 6.25 Volts at the distributor from the primary wire from the coil when the key is on and 0 when the key is off.

Could I have a bad coil? How do you test the coil?

Picture of my truck it attached.

Tom

 

When was the last time that you replaced the grommet or the wires in the distributer. Open it up and look for something that could be grounding itself out.

 

Check ALL the grounds and don't forget the one from the motor to the chassis/frame.

 

I can't see any problem inside the distributor and there do not see to be any shorts at all in that circuit. There seems to be little or no spark at the points with the distributor cap off. Very strange to me - these engines are just not that complicated.

 

Did you try a new condenser?

 

it could be the condenser.

 

I tried another one I had but not new.

Could I have a weak connection at the ammeter to the ignition switch? I get 6.25 Volts but maybe not enough current.

Even though it ran great for a couple of years before it wouldn't start, I think I will just get all new points, condenser, rotor, cap, plugs and coil. They are all at least 20 years old. Couldn't hurt, right? Only thing is that if it runs after that, I won't know what was wrong.

 

When I was running points I usually changed them two to three times a year. I had customers that came into the shop for an oil change and tuneup if that gives you any idea of point life in the real world.

 

Goregeous pickup justafan!

 

i had the same problem with my 40 dodge pu. turned out it was the headlight switch touching the back of the dash. the truck had a after market switch in it and once the main power wire broke inside the connector. i would crank it and rotate the switch back and forth and the truck started. i repaired the wire and all was good. vintage power wagon in iowa makes a electronic conversion that works great. hope this helps you out

 

OK thanks for the latest tips (and compliment, earlymopar). I will have time to spend on it Saturday morning. I will check the wiring under the dash and try bypassing that with another wire from the battery directly to the back of the coil. With a toggle switch, just in case it starts!

 

Use a seperate battery for ignition. That way it will eliminate the draw of the starter from robbing voltage for the coil.

 

Thanks NoboD - you said that a few days ago too - should have tried it then.

 

It solves and creates several differant things. It can prove your coil and distributor are to blame or NOT. It also lets you know whether the problem could be in the wiring, or starter. I use it as a diagnostic tool. You could even hook the coil to the car system, and isolate the starter and turn it over with a 12 volt to prove a few things.

 

OK, problem solved!

I took noboD's advice and hot wired from the battery to the primary on the coil and it started right up. So the problem was under the dash. When I inspected it I saw that the nut holding the feed to the ammeter and the ignition switch was a little loose. I cleaned up the ring terminals and tightened it back down and took it for a nice ride. Thanks for your help.