Help - Engine Does Not Shut Off

[tom1394racing]

Last weekend I completed the install of my hot rod 3.0 twin plug into my '73T turned RSR clone. The engine oil pressure primed and the engine started on the first crank but I have a small problem.

Here's where the problem comes in...When I connected the fuel pump wire I noticed that the fuel pump ran even though the ignition switch was off. I decided to go ahead and start the motor anyway and deal with the fuel pump problem later. I also noticed that the red warning light for the alternator on the dash did not illuminate. I stated the car and ran it in for 20 minutes until the T-stat opened up and allowed oil to flow to the front cooler. The alternator light did not come on during the engine run in and the engine ran beautifully.

When I shut off the ignition key the engine continued to run as if nothing had happened indicating that the electrical feed to the MSD system was still active. I had to pull the coil wires to get the engine to shut off. In addion the oil temp indicator was not working.

This morning I disconnected the hot lead from the battery to the starter and found that the fuel pump functioned properly and was powered only when the ignition switch was on.

It appears that the hot lead to the starter was powering the fuel pump and the MSD feed through the ignition switch. I figure that I either have something crossed up in the engine wiring harness/14 pin connectors (which I completely rewired) or I have a bad alternator.

Any suggestions on where to start to diagnose the problem?

[tom1394racing]

Here's some more information based on some testing and some corrections I made this morning.

I now have an alternator light. The red/black switched power to the alternator bulb was not connected.

With the hot lead to the starter disconnected, all of the instruments apprear to function properly and respond to the ignition switch positions as designed. This includes the fuel pump and the switched hot lead to the MSD system.

Once I connect the hot lead to the starter, Everything (fuel pump, power to MSD, alternator light, fuel gage) powers up even though the ignition switch is in the off position. It seems that the starter hot lead is feeding power through the alternator, through the fuse at the rear electrical panel and back through the ignition switch.

John Cramer, John Walker or Warren Hall....Can you guys help suggest a fix or a diagnostic path?

[tom1394racing]

Oh....BTW....Now the alternator light stays on when the engine runs and I have 12.5 volts at the battery terminals.

Bad alternator or bad connections???

[K. Roman]

Hmm. Not sure but I'll bump.

[tom1394racing]

My next step in this process is to re-check all of the electrical connections from the engine wiring harness to the 14 pin connector going up to the front of the car from the engine compartment. I am avoiding pulling and checking the alternator as my last resort because the alternator worked fine before starting this project.

FYI...I am using the original alternator and wiring harness from the '73.5T CIS starter car. I removed all of the CIS wiring (WUR, Cold Start, thermo switch, etc) and made a new harness. This is why I think the problem is in the wiring connections rather than the alternator.

Help from the experienced experts will be greatly appreciated.

[911Velocity]

I have a 6al MSD box along with a blaster II coil in my 67 vette and after I swapped the original engine out for my 540 I noticed a few abnormalities. One of these my shed light on your problem. Read the MSD system instructions carefully and I believe that the power is going through the starter then the coil and back into the instruments. In my case the ammeter gauge reads backwards ie. when I am running and charging properly the gauge shows a discharge and vice a versa. I recall reading something in the instructions for the MSD installation about the current flow is opposite to what it used to be. Usually it goes from coil to starter and in the MSD case I think it goes to the starter first then coil. I have not had time to go back yet as I just disconnected the gauge and everything else works fine. I will reverse the wires and see if that fixes my problem. I don't know if this helps but I bet it has something to do with the MSD system.

Best regards,
Gerry

[dean]

Tom,

If it were me, I would check the 14 pin connector first. It is easy to mess up there a little. Gee I wonder how I know that.

Dean

[RoninLB]

If it was my prob I would rig the small dia red on/off trigger wire so it can be disconnected after the engine is running. If engine stops after disconnect the prob is close to being solved.

[pa911]

When mine would not shut off the problem was in the front relay panel.the P.O had a couple wires crossed.

[john walker's workshop]

you can't run the pump or anything like the ignition from the same terminal that powers the alternator unless you have a diode inline.

[tom1394racing]

John Walker...Is my fix to put an in-line diode on the small red wire that runs from the alternator through the engine wiring harness to the rear control panel?

Why would I need to change from the factory wiring setup? I would think that, with everything properly connected, the system should operate as designed without a special diode. What is the function of the diodes in the alternator?

Now that said...... I have made major changes in the wiring in the area of the rear control panel. The car no longer has the rear window defrost, the RF suppressor, the WUR or the cold start solenoid. However none of the were designed to prevent current flow back to the front of the car from the starter like a diode would.

John...When you say, "you can't run the pump or anything like the ignition from the same terminal that powers the alternator, how would you suggest re-wiring? I still think I have either a wring connection wrong or my alternator is shot.

[johnsjmc]

On my 3.6 conversion into a 1980 I had to disconnect the red wire at term #2 on the 14 pin . There is another red at #14 which goes to the alternator or rear relay panel(can,t remember). If you don,t remove one of these reds it backfeeds everything. I thought a 1973 didn,t use a fuel pump relay originally perhaps you need to add one.
The diodes in the alternator are there to convert the AC it makes into DC.

[tom1394racing]

This seems to make sense based on the 1965 wiring diagram attached. The early cars seem to have only one wire (D+ 61) feeding from the alternator to the voltage regulator and then to the alternator bulb.


The '73 wiring diagram shows a second red wire that leads from the B+ post on the alternator to the rear fuse panel. I think this wire is powering my fuel pump, instruments and ignition when the key is switched off. Since the simplified '65 wiring diagram does not show it...I'll try disconnecting it.

[tom1394racing]

FYI...

Disconnecting the B+ wire to the control panel did the trick. Fuel pump, ignition and instruments now operate properly with the ignition key. Engine shuts down properly.

I still have 12.5V to the battery when the engine is running and the alternatorr light does not go off.

I'll have to remove and check the alternator and its connections next.

[wilke3169]

Tom, when I reinstalled after rebuild I had the same symptoms. I had the connections reversed at the alternator. Changed these and the light went out and charging was restored.

[Joe Bob]

The D+ line needs a diode....read the instructions....