starting issue on new engine install

[juggernaught]

Just tried to fire up the newly rebuilt 360 yesterday only to have a minor issue bring everything to a halt. The engine would start and run ONLY with the ignition key rolled all of the forward (in the start position). As soon as the key rolled back to the RUN position the engine stops.

I have not done an extensive investigation yet, but I do know that I am showing NO voltage at the ignition relay when the key is turned ON (RUN position). I have looked at several wiring diagrams for the ignition relay and everything seems to be O.K., but need to look closer again.

All of this was disassembled 1 year ago, but I believe that the wiring to the relay was never removed. Everything was running when disassembled. I have been under the steering dash doing alot of wiring and may have disturbed something, but the ignition swith was never removed.

Can anyone give me a good trouble shooting procedure for my 1978 cj7 ignition relay? I know that the POS. wires to the Batt. are off one side and the starter motor wire is off the other side (both large terminals). That leaves the two relay wires (one red , one blue) on the top of the relay. Not yet sure which wires are from where,go to where or do what yet. All of my books are vague about this relay.

One more thought, I do have a t-18 4spd with a neutral safety switch (two wire module on top of tranny case. While the wires are plugged in to the module, I am not absolutely sure that the tranny is in a "neutral" position. The twin sticks are presently both in neutral. If I check the wires coming out of the tranny should there be continuity?

[tufcj]

There are 2 circuits to the coil. One supplies a full 12 volts with the key in the "start" position, the second supplies a lower voltage in the "run" position, either thru a ballast resistor or resistance wire. Were any changes made under the dash, either to the ignition switch or steering column?

The connector on top of the T-18 is for back-up lights, it has nothing to do with a neutral safety. Neutral safety is only on automatic equipped vehicles. Later vehicles had a clutch switch.

The starter solenoid on the fender will have the 2 small posts marked "S" and "I". "S" is start, and the blue wire goes there. "I" is ignition. Can't help you past that.

Bob
tufcj

[juggernaught]

Thanks for that much. Wasn't sure about the neutral switch(its been awhile), but that rings a bell.

I believe I got rid of that resister to the coil because the new coil( super coil?) said it didn't need one. Not sure.

Unfortunately, my starter solinoid is not labeled with an "S" or "I" that I can see. Will look closer.

No changes were made to the ignition switch or wiring (intentionally).

I believe the key to my problem lies in the fact that I have no power to the relay after the key returns to the "RUN' position. Why that is I cannot figure out yet.

Thanks for eliminating a couple of more things.

[msalaba]

The starter relay only receives power (+12vdc) when the key is in the "start" position. As previously stated, the second wire on the starter relay was to provide +12vdc to the coil bypassing the resistor wire for easier starting.

Looking at the attached schematic, it looks like there is a wire that goes straight from the ign switch to both the coil and elect choke that should be +12vdc in the "run" position.

I would hazard a guess that you are missing a wire to your coil or have a connector somewhere that needs connecting.

http://c2.ac-images.myspacecdn.com/images02/142/l_dc05b7b94dc741c18685f85746f886ed.jpg

[msalaba]

Oh, and if you were having a problem with a neutral safety switch, the engine would run but not crank.

[juggernaught]

Temporarily solved the problem by jumping the red wire on the relay directly to the pos. battery term. The engine runs fine.

This red relay terminal ( I believe it is the ign. post) is supposed to be "hot" when the key is turned to the "run" position. Mine is NOT hot in the "run" position. This is the same wire that goes to the positive side of the coil.

Tomorrow I will buy a new relay and see if that works. I still have my doubts.

[Old Rugged Crosser]

Save your money on buying that relay. That is not your problem.

Your problem is either the ign. sw. or the wire that should go from the ign. sw. to the coil. Take your meter and make sure that when the key is turned to run that you have power on the terminal that sends voltage to the coil. If in the run position and you have no voltage at the ign. sw. then your problem is the ign. sw. If you have voltage at the ign. sw. on the run position then run a wire from that terminal to the coil. Your relay is acting as it should.

[juggernaught]

ORC.........that was our first thought. My problem is exactly how ( and where) to test the ignition wires since they are so hard to get to and I don't know exactlly which wires to test.

I would still like to know whether the power to the coil comes from the relay when the ignition is in "RUN", or from somewhere else( the pos. coil wire(red) is split at the coil).

I would also like to know if the "other" ("I" ?) wire is supposed to be HOT in START position, the RUN position or both.

[fuzz401]

might help you compleat for a 78 jeep

http://smg.photobucket.com/albums/v153/fuzzgremlin/cj%20wiring/

[msalaba]

ORC.........that was our first thought. My problem is exactly how ( and where) to test the ignition wires since they are so hard to get to and I don't know exactlly which wires to test.

I would still like to know whether the power to the coil comes from the relay when the ignition is in "RUN", or from somewhere else( the pos. coil wire(red) is split at the coil).

I would also like to know if the "other" ("I" ?) wire is supposed to be HOT in START position, the RUN position or both.


You are barking up the wrong tree. The relay you keep mentioning is the starter relay. It does 2 things, both when the key is in "start", sent +12vdc to the starter motor and +12vdc to the coil. It does not supply any coil power in the "run" pos. hence the name "starter relay"

The coil gets power in the "run" pos. directly from the ign switch "run" circuit. That is why from the factory there are 2 wires to the + side of the coil. The - side is fired from the Duraspark module. (Or breaker points on older jeeps) This allowed 12v to the coil for easier starting and 6v to the coil for normal operation. The old round coils are rated for 6v and thus had a resistor wire to bring 12v down to 6v so the coil didn't burn out.

You mentioned that you installed a new coil rated for 12v. I'm assuming you did not hook up the wire from the ign switch that runs through the resistor wire to the coil.

If you have an electric choke wire, you can check for +12vdc there. If you have power there, you ign. switch is fine, you are missing a wire to the coil. If you do not have power there, look for an unplugged connector or a bad ign switch.

I hope this helps... :-|

[msalaba]

http://c2.ac-images.myspacecdn.com/images02/149/l_b22fba6069fe48e5a7298b7f10a724dd.jpg

[msalaba]

http://c2.ac-images.myspacecdn.com/images02/149/l_b445865179f842b3939c3f531ba5daa1.jpg

[msalaba]

http://c4.ac-images.myspacecdn.com/images02/76/l_62256a5fc1004bcc978f94d365c90e07.jpg

[Old Rugged Crosser]

Masalba wrote:

No changes were made to the ignition switch or wiring (intentionally).

I believe the key to my problem lies in the fact that I have no power to the relay after the key returns to the "RUN' position. Why that is I cannot figure out yet.



Your problem does not lie in the fact that you have no power to the relay after the key returns to the "RUN" position." It is NOT supposed to have constant power. Your relay is a momentary contact relay. Meaning that it only works while the key is turned to start.

I just checked my Key Sw. which has 4 terminals: Batt, ign, acc, and st., all marked on the key switch. Yours will have these markings too. The st. term. is for the start switch relay ; your momentary cont actor which will only have power as long as the key is held to start. The ign. is the run position which you should have a wire running from there to your coil. The Batt. is the power supply from your batt. through your fuse panel. The acc. is for the radio, fan, ect.

By the way I am a retired electrician. :sa: :sa: :sa:
Masalba wrote:

No changes were made to the ignition switch or wiring (intentionally).

I believe the key to my problem lies in the fact that I have no power to the relay after the key returns to the "RUN' position. Why that is I cannot figure out yet.

[juggernaught]

Thanks for all the help guys...after tracing the "other" red wire back from the coil and thru the fire wall I was able to find a modular connection that had come apart in mid-wire. Problem solved.

Now one issue down and several hurdles left, but the engine is running properly and we are dialing in the carb.

Both Msalaba and ORC were right on the money. 500 bonus points are awarded to you both for this round. Thanks.

[msalaba]

:?

I got 500 Bonus points!

:lo1l:


Glad your problem was sovled