Searching for a short?

[wartmeister]

1969 F100 total rebuild and wiring completed last fall. Original 240 inline 6 motor, but everything else is new. 400 miles driven, no issues. Then, all of a sudden, the engine dies at a stop sign and won't restart. No turnover, just the dreaded click. Battery has 12.5V across the terminals and starter solenoid is good. Dash voltmeter gauge reads 4-6 V and fluctuates as expected when lights are turned on, etc. I diagnosed it as a short, removed the fuses one by one and looked for a rise in the voltmeter, but no change. Don't know what to look at next. Any suggestions?

(I posted this yesterday, but forgot to title it, so even though I couldn't find it, this post would be similar to that one.)

[cep62]

That sounds like a bad connection.
When you jump it does it start ?
Do you have good grounds? , you say everythings new , is it painted?
because that can cause issues .
make sure the solenoid has a good ground either through the inner sheet metal , or better yet a heavy wire to the mounting bolt.

Do you have good battery cables ?, or the bolt on repair ends ? those can cause issues too.

Try to bypass the solenoid and see if the starter turns that way ,(warning that will cause sparks)

Let us know

[sargentrs]

Don't assume the solenoid is good. I've replaced one 3 times because 2 were bad right out of the box. I always start by checking all connections. Had a similar issue one time. Turned out to be a bad crimp on the ring terminal at the brown wire from the alternator to the solenoid. Wiggled the wires and it pulled out of the terminal. Crimped a new ring on it and that fixed it.

[wartmeister]

Thanks. Great inputs from both.

Sorry, I tried jumping it right off and it didn't change a thing. I also replaced the solenoid with no luck. All cables are new.

The truck was repainted and I was very detailed about grounding...scraped paint down to metal, battery to engine, engine to cab, cab to frame. I'll recheck them all anyway. Considering that this happened after 400 miles seems to indicate something wiggled loose.

More questions:
1. Grounding the solenoid: Now the solenoid is connected to the inner fender (Sheet metal) with two sheet metal screws. I'm not sure how to connect a wire to the mounting bolt...can you expand on this?
2. Bypassing the solenoid: should I just touch the starter cable to the positive post on the battery?

[sargentrs]

When mounting the solenoid, or anything grounding through the mounting, I prefer to use through bolts, external locking star washers and lock nuts. As for jumping across the solenoid the old school way is to use a screwdriver to connect the battery side of the solenoid to the starter side at the cables. I've used jumper cables, pliers, screwdrivers, tire tools, etc. However, the "professional" way is with a remote starter switch. Ever since I bought one, I've never used anything else. Also comes in handy any time you need to bump the engine over to find TDC or setting timing.

[cep62]

More questions:
1. Grounding the solenoid: Now the solenoid is connected to the inner fender (Sheet metal) with two sheet metal screws. I'm not sure how to connect a wire to the mounting bolt...can you expand on this?

The solenoid grounds with the sheetmetal screws to the inner fender.
on some vehicles (old & rusty like mine.) the inner fender doesn't conduct electricity very well ,
so a heavy wire from the neg battery post to the mounting screws ensure a good ground.

Bypassing the solenoid: should I just touch the starter cable to the positive post on the battery?

Sparks by the battery can be a bad thing .
The remote start button is a good idea , but a starter may draw too many amps for a basic one.
A jumper cable from the pos post to the starter cable will do it.
So will a big pair of channel lock pliers , just grab both sides of the solenoid and squeeze.

[wartmeister]

All great inputs. Will be a few days before I can get it done and get back...more to follow.

[sargentrs]

The remote start button is a good idea , but a starter may draw too many amps for a basic one.

Excellent point, cep62! I forgot to mention that it should only be used for short bursts of pulling the trigger to bypass the solenoid, checking the starter circuit, not for extended cranking. It WILL overheat the wiring on the switch.

[cep62]

not for extended cranking. It WILL overheat the wiring on the switch.

Don't ask me how I know.

[ddcrim]

Have the battery tested under load. If it was a real short, I would expect smoking wires. 12.5 V is low, and less than that with the lights on may be a battery problem.

[wartmeister]

Got to it this morning.

Current result: Still getting just a click from the starter and showing 4V on the dash voltmeter after:

1. Tried two different fully charged batteries each showing 12.5V across the terminals...same result.
2. Grounded the starter solenoid to the battery...same result.
3. Used a remote starter...same result.
4. Checked all grounds and found none loose...tightened them anyway...same result.
5 Voltage check from battery to motor and battery to frame all show 12.5V.

Could it be the starter? Any way to tell if it is the starter. I have not gone down this path because it doesn't explain why the low voltage on the dash voltmeter. Also, taking it out is a bear because the headers need to come off.

I definitely need some help here.

[sargentrs]

Sorry if I get long winded here. Easiest way to check the starter is with jumper cables. Make sure you're in neutral, wheels chocked and E-brake set. Hook the ground clamp to the bell housing mounting bolt clamping the bolt, mounting ear on the starter, and the bell housing. Hook the red clamp to the mounting bolt and battery cable on the starter. Hook the other end ground clamp on the negative battery post. Now just briefly touch the red clamp to the positive battery post just long enough to see if the starter bumps over. If so, turn the key on and touch again long enough to see if it starts. DON'T clamp it on the hot post! If it starts you don't want to keep the starter engaged with the engine running. If the starter doesn't turn over, that's most likely your problem. If the starter turns over with the jumper cables but still does the same thing, try this..I had a similar isue with my son's '85 5.0 Mustang., drove us nuts. Finally pulled the starter off and the bell housing and starter were caked with greasy gunk between them. Cleaned both thoroughly and scuffed both surfaces with ScotchBrite. Bolted the starter back on and she fired right up. She was just not getting a good ground between the starter and the bell housing spacer plate/dust shield.

[sargentrs]

If the starter bumps over but it still won't start with the key, time to start detailed checking. Do you have a voltmeter? Set it on 12v and put the tip of the red lead in the center of the hot post, not on the clamp yet, and the black lead in the center of the negative post. Press it in there good and firmly making sure you hit clean lead. Check for 12v. Good? Turn the key to on, check again. Good? Turn the key to start, check again. Good? Move to the clamps. Black lead still on the negative post. Check for 12v. Good? Turn the key to on, check again. Good? Turn the key to start, check again. Good? Move the black lead to the clamp on the ground cable.. Check all 3 times again, key off, key on, key start. Move to the cable behind the clamp. Put the black lead on the negative post. Check for 12v, etc. After verifying hot cable, move the black lead to the black cable. Check again, 3 moves. Put the black lead on the negative post again. Move the red lead to the other end of the cable, Check again. Perform all these tests, first with the black lead on the post, then with the black lead on the closest ground connection.

Check all of these points:
Post
Clamp
Battery end of cable
Solenoid end of cable
Solenoid mounting nut.
Solenoid post
"I" terminal on the solenoid
"S" terminal on the solenoid
Starter side of solenoid post
Starter side of solenoid nut
Solenoid end of starter cable, black lead to solenoid mounting screw, the mounting plate on the solenoid.
Solenoid end lug of starter cable
Solenoid end at the cable itself.

All the way down to the mounting lugs on the starter cable for the hot cable and the closest ground will be the starter case itself. Record any results where the connection does not read 12v, "I" terminal on solenoid will read around 9v. Gotta trace the entire circuit, every connection, every wire, etc to narrow down where the fault is. If you find a break, then clean and double check the connection. Your problem will be somewhere in between. If all that checks out, the issue is further back along the chain, possibly back to the ignition switch, voltage regulator, alternator wiring, even the wiring harness itself.

[wartmeister]

OK. I have done some of voltage checks you point out, but not with the key on and in start. I will hopefully get to it this week. I like your systematic approach and have a couple questions just to make sure. I put it in checklist form:

Checking the starter with jumper cables.
1. Make sure you're in neutral, wheels chocked and E-brake set.
2. Hook the ground clamp to the bell housing mounting bolt clamping the bolt, mounting ear on the starter, and the bell housing.
3. Hook the red clamp to the mounting bolt and battery cable on the starter.
Is this is where the red wire is connected to the starter from the solenoid?

4. Hook the other end ground clamp on the negative battery post.
5. Now just briefly touch the red clamp to the positive battery post just long enough to see if the starter bumps over. If so, turn the key on and touch again long enough to see if it starts. DON'T clamp it on the hot post! If it starts you don't want to keep the starter engaged with the engine running.
6. If the starter doesn't turn over, that's most likely your problem...meaning the starter isn't sufficiently grounded?

I had thought about the starter not being sufficiently grounded but there hasn't been much time for gunk build up...I'll also check the that the starter mounting bolts are tight. I am suspecting that the problem might be in the wiring to the ignition switch or wiring harness as you point out since the dashboard voltmeter reads low when key is on, not just in key start.

I'll get back when I've completed these tasks. Thanks again.

[sargentrs]

Checking the starter with jumper cables.
Is this is where the red wire is connected to the starter from the solenoid? Yes.

5. Now just briefly touch the red clamp to the positive battery post just long enough to see if the starter bumps over. If so, turn the key on and touch again long enough to see if it starts. DON'T clamp it on the hot post! If it starts you don't want to keep the starter engaged with the engine running.
6. If the starter doesn't turn over, that's most likely your problem...meaning the starter isn't sufficiently grounded?
Not necessarily, but most likely. Could be a bad place in the hot cable from the battery. It's been discovered before, in old battery cables, that the insulation gets a crack/break in it and allows moisture to get in corroding the wires. Won't see it at either end but it'll have a bad place somewhere in between.

You do check all connections with key in on and in start though. These connections can read perfectly fine with no load on them but once the load is applied, the fault occurs.