No spark at distributer

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Feb 10, 2014 | 09:29 AM

#16

fmc400

MSEE

Joined: Apr 2004

Posts: 10,386

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From: Austin, TX

Glad to hear it's moving forward. What specifically are you jumping on the solenoid to keep it running? I assume the battery post to the 'S' post? Does that mean the starter stays engaged during the brief period you keep it running?

Feb 10, 2014 | 01:10 PM

#17

benbuilder

Thread Starter

Fleet Mechanic

Joined: Sep 2012

Posts: 1,608

Likes: 53

Yes, this is exactly what happens. The engine will only stay running if I have made this contact. Is this normal? I can try to chase down all the wires to the ignition and try to use this. In any event, We got the engine running. I replace the coil and still had no spark at the plugs. I lifted the wire arm on the rotor so it made contact with the distributer and then it started to fire. Thanks so much. You are patient.

Feb 10, 2014 | 02:50 PM

#18

cbenz73

Junior User

Joined: Dec 2013

Posts: 59

Likes: 0

See you have a separate circuit that is used for ignition during starting, because of the voltage drop during the large amperage draw.

Feb 10, 2014 | 03:21 PM

#19

fmc400

MSEE

Joined: Apr 2004

Posts: 10,386

Likes: 35

From: Austin, TX

If the engine fires while the key is held in START, but shuts off as soon as the key is released to RUN, it's an indication that the ballast resistor is open circuit, or the ignition switch is failing.

Turn the key to RUN without starting the engine, and measure the voltage at the positive terminal of the coil. Report your results.

Feb 17, 2014 | 07:01 AM

#20

benbuilder

Thread Starter

Fleet Mechanic

Joined: Sep 2012

Posts: 1,608

Likes: 53

My problem is that I am starting the truck from the solenoid. I am jumping the battery post to the 'S' post. The engine will run as long as these two are connected. I do not have the keys to this truck. Is this normal not to keep running from the solenoid? I will get another ignition switch if needed.

Thanks

Feb 17, 2014 | 07:33 AM

#21

fmc400

MSEE

Joined: Apr 2004

Posts: 10,386

Likes: 35

From: Austin, TX

No, it's not normal. The engine should be able to run without the aid of the solenoid (otherwise the starter would grind into the ring gear the entire time the engine is running). See my above post for the two possible culprits. The test I described is a good starting point to help determine which.

Feb 17, 2014 | 07:51 AM

#22

Don Senkow

Mountain Pass

Joined: Jun 2004

Posts: 241

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From: Canada

If you haven't any keys, how are you turning the ignition on? Jumping from the battery terminal to the S terminal will turn the engine over and through the ignition ballast resistor circuit will fire the engine That is what it is supposed to do. With the key in the run position, do you have voltage? That question, I believe has been asked. If you don't have a key, did you measure the voltage at the coil +?

Run a jumper from the Battery positive to the Coil +. Then try jumping the Battery to the S terminal. If it starts and runs, you must repair the ignition run circuit. Don't leave it like this as the points will burn after a few minutes.

Feb 17, 2014 | 08:08 AM

#23

fmc400

MSEE

Joined: Apr 2004

Posts: 10,386

Likes: 35

From: Austin, TX

That's a great point. I missed the part about the keys missing. For the engine to keep running after the jump is removed, the key needs to be left in RUN. Maybe this is a good time to have the keys made, since you'll need them anyway. A locksmith can make a key from the tumbler pins if you bring in the tumbler. If the truck is all original, either door and the ignition should be the same. Since you need the key to take apart the ignition switch, the door would be the best bet.