Wiring for test start

[specialty]

anyone have a simple wiring diagram to test my CJ3A engine? I have the tub off restoring the body and frame and want to run the engine before installing the tub back on. I have heard the engine running but the carb. had gas running out after being not run for a long time. I am going to rebuild the carburetor, change the oil and filter and see what happens. May  also need a fuel pump. Also what is a good replacement oil? I had a few old trucks and they used 30w non detergent.  I have  read people using Rotella for the zinc though. Thanks

[athawk11]

Specialty,
We can help you with this basic circuit, but some changes might have happened over the years that we will need to know.

Do you have a starter solenoid?

Also, I like Rotella-T 15w-40 for my Willys.  I will also add some ZDDP additive on occasion.

Tim

[specialty]

I have what was on the Jeep when I bought it a few months ago. I heard the engine run briefly but fuel was running out of carb and the po said he thought the fuel pump needed rebuilt also. I am going to rebuild the carb and see if the pump is working. Hopefully I will be able to see if it runs in a few weeks and see what all it needs. I don't think anything has been altered. All appears to be original. Thanks for the help.

[athawk11]

Per your answer that all is original, this is all you actually need to start your CJ3A.

 

Note:  In the drawing, the wire from the ignition switch (IGN) to the coil (+ side)�

You will likely find this wire attached to an ammeter terminal, and then another wire from the other ammeter terminal that attaches to the ignition switch.  I didn�t draw the ammeter in because it has no factor on whether the Willys starts or doesn�t start.

This is also true with your generator and regulator.  They do not need to be in the equation for a Willys to start.

Also note:  Not drawn in are the spark plug wires, but they are clearly important.  They must be connected and in the correct firing order.

Here is a drawing that includes the ammeter...

[macrisel]

Hawk.....that drawing is better than most of the ones in the service books!!

[athawk11]

Thanks Mark!  Just trying to pass along the help that you all gave me back in the day.

Tim

[aboyandhisdog]

Tim, you are truly a man of many talents!

[bretto]

Sorry, I have to give my appreciation to Tim's illustration as well, nicely done my friend.  Are you a lefty?

[BMIC]

Ditto Tim

[athawk11]

Thanks again guys.�

Bretto...yes, I'm a lefty.� How can you tell?  Is it the lean? 

Tim

[specialty]

Thanks Hawk, this will be a lot of help.

[specialty]

The reason I asked is all the wiring looked like the rats got into it. I don't even know how it ran for as long as it did. When I removed the tub most of what was left of the wiring is finished. I am going to get another Harness or just run the wires myself. Doesn't look like to mush wiring is involved here. Thanks again.

[OkieFarmJeep]

You can eliminate the key switch as well.  I keep a long bit of wire with two alligator clips in my tool box. One to batt pos the other to the pos coil. Hence the term "hot wire a car".  That way you don't need the tub on or key switch from it.   Dito on your illustrations Tim!

[JeepFever]

Very nice drawing Tim!

I have to admit I was questioning it at first though.  Ground from battery to frame?   I would have thought the ground should go straight to engine block.   That would be a more reliable connection for this really high amp duty.

I went to look at Hoover, and sure enough -> a short cable from battery to bracket,   then another short cable basically going around the rubber motor mount.   Both of mine are in really bad shape,  and will have to be replaced when the time comes.   

I wonder if this design is decendant from wwii MB's trying to save copper?

Lesson learned ->  do not question athawk.   

[athawk11]

Jeepfever,
Thanks for chiming in.   
Grounds are critical for proper function of the entire electrical system.  Grounding the frame makes it easier to ground the tub.  The tub needs to be grounded so the lights, fuel sender, fuel gauge, regulator, horn, etc, will work.  If an electrical component doesn't work, the first troubleshooting step should be to make sure it is properly grounded. 

There may be better ways to ground the system, but this is the Willys way.  Personally, I've added more ground points to my projects than CJ3As had originally.

Okie, you're right, the key switch isn't technically needed.  If you have one and can temp mount it somehow, it's a fairly safe way to start and stop the circuit...