Non-Starter - now a starter and appears to be a runner!

Dave-R · Post by **Dave-R** » Tue Oct 08, 13 3:25 pm

See if the case is connected to the ground terminal with your meter.

To check the resistance of cables, connections and switches, measure the resistance of the cables alone first. Then in series with the switch or connector you are checking to see if there is any difference.

Stu Twin · Post by **Stu Twin** » Sun Oct 27, 13 12:42 am

Recap,
Was getting low voltage to coil, so i got an NOS (unused) Ign switch to swap. Before fitting i measured a few resistances for comparison between old & new:
Old switch.
Between 'Batt' & 'Ign1' terminals = 7 ohm
Between 'Batt' & 'Ign2' terminals = 0.8-1 ohm
New switch.
Between 'Batt' & 'Ign1' terminals = 0.5 ohm
Between 'Batt' & 'Ign2' terminals = 0.5 ohm.
Great, i thought, that'll be the problem. So with new switch fitted i gave it a go.
No change, still low voltage to coil. Haven't run it yet but i guess it'll be the same as before. So i've checked a few more resistances in the wiring:
Blue & white wire between voltage reg and bulkhead fitting (IGN1) fitting = 0.4 ohm. (new loom)
Brown wire between ballast resistor (still fitted for now) and bulkhead fitting (IGN2) fitting = 0.4 ohm. (new loom)
Between ignition switch plug (IGN1) and front of bulkhead fitting = 0.7 ohm. (old dash loom)
Between ignition switch plug (IGN2) and front of bulkhead fitting = 0.4 ohm. (old dash loom)
So the question is, is the slightly higher resistance in the old IGN1 / run wire likely to be causing the drop in voltage?
I could try to replace the wire or clean the terminal in the back of the bulkhead fitting but it's a pain to get to. And a new dash loom is $550!
i did wonder if the newish 'Made in taiwan' starter relay could be causing problems so refitted old original one, but that made no difference, got the same readings.
Thoughts ???

Steve · Post by **Steve** » Sun Oct 27, 13 9:25 am

Interesting matey.....watching this one closely. Is it worth trying a hotwire from the + battery post to the + coil terminal then bridging the relay to crank her over (Terry R taught me this....naughty man!!). It will put 12V to the coil for an instant then remove the lead straight away so as not to fry the coil. At least then you will know it is a wiring issue maybe. Just a thought...

I am watching your testing process really closely as I am getting close to fitting HEI to mine (no coil still!!)......

Also, is it worth bridging the ballast resistor just for this test maybe???....dont think it will hurt the coil just for a go but sure Dave could clarify that...

Cheers Steve

Dave-R · Post by **Dave-R** » Sun Oct 27, 13 10:36 am

You should have12 volts on one side of the ballast resistor. If you have not then the feed to or from the ignition switch is bad. If you hot wire from the battery to the12 v side of the resistor you bypass the fault. If the problem is the resistor then you wire to the lower voltage side but the coil will run hot which will be ok for fault finding.

Stu Twin · Post by **Stu Twin** » Mon Dec 02, 13 1:14 pm

Another question…
What could be causing the engine to stall when it’s put into drive?
Seems to start & idle ok but as soon as it’s shifted into gear, if the revs aren’t kept up, it dies.
Got it warmed up and pulled it out the garage, but went to drive off and it just dies. Managed to reverse back in fortunately.
Strange as it’s only just started doing this.

I realise it could be several things:
Carb, (supposedly rebuilt before getting the car back on the road)
Vac leak, (not checked as I haven’t got a gauge)
Timing, (still needs sorting)
Torque converter. (rebuilt).

Where’s best to start?

One other thing i noticed, with the engine idling, the voltage at the Alternator 'Batt' terminal, to earth, is 15.2V. This increases to 15.3V with a few revs. Seems rather high - will this knacker the battery? i can try the V/Reg off the Dodge to see if it reduces. (It's what i presume to be an electronic version of the old original one ie looks the same from the front but without the old fashioned bits at the back. Probably made in China though)

TIA,
Twinsters.

Dave81 · Post by **Dave81** » Mon Dec 02, 13 1:31 pm

So I take it that its relative to RPM. Hence when you put it into gear and the revs drop it basically stalls the engine......

Have you adjusted the Idle RPM up to see if it persists??

RobTwin · Post by **RobTwin** » Mon Dec 02, 13 1:37 pm

That's right Dave, you (we) need to give it plenty of revs to stand any chance of it not stalling; if you just shift into gear without touching the throttle, it dies.
We have already raised the idle speed to see if it helps, to no avail. When warmed up, it's around 1000 - 1200. Only approx as we haven't fitted the tacho yet! Didn't want to damage it till we get the gremlins sorted

Pete · Post by **Pete** » Mon Dec 02, 13 1:44 pm

You need to sort timing and idle mixture out first.

Then look to see if Convertor is too tight. You need a Rev counter or use of the Snap on timing light to work all this out....and a vacuum gauge is indispensible too!!!

Adrian Worman · Post by **Adrian Worman** » Mon Dec 02, 13 2:12 pm

Anywhere around 14.5-15.5 is not uncommon on a running engine, any greater is not good but you'll find the regulator max output settings are ok at this voltage.
If you have a new loom and don't have a bulkhead connector like an aftermarket loom does, you can easy see 13.5v plus at the ballast.
My money is on the loom, spesh the bulkhead conn and the ign switch conn providing too much resistance. Unfortunately just cleaning terminals and such wont make any real difference if the wire has lost its capacity due to age, corrosion, heat etc

Dave-R · Post by **Dave-R** » Mon Dec 02, 13 3:04 pm

Stu Twin wrote:Another question…
What could be causing the engine to stall when it’s put into drive?

In this order;

Not enough initial timing.

Too lean an idle mixture or the throttle blades not in the correct position at idle.

Not enough stall speed in the torque converter.

Start with the timing and work down the list. As Pete says the first two will probably cure it.

Stu Twin · Post by **Stu Twin** » Mon Dec 02, 13 5:22 pm

Thanks chaps,
Ok, i'll get me a vac gauge.
All I can think that might have changed the way it runs recently is that I evened up the 2 idle mixture screws in the side of the carb.
I think 1 was maybe ¼ or 1/8th of a turn set differently to the other, so set them both the same. 1.5 turns out i think (from all the way in).
So maybe 1 is a little leaner than it was. I know they're sensitive but i didn't think it was that sensitive?
I'll go out 1/8 turn each side (at a time) and see if that helps. And then i'll see what the timing is. Think it was 14 BTDC from memory.

Ade - the engine side of the Ign loom is new. The bulkhead conn is still in place. I may well still be having resistance issues from this.
So from my memory of O level physics, if V=I x R, does that mean if resistance is high, then the voltage will be hgh too? for some reason i was thinking resistance would reduce the voltage. Told you i was crap at electrics!

Stu.

Dave999 · Post by **Dave999** » Tue Dec 03, 13 10:00 am

Voltage = the total of all resistances x the current

so the total voltage across the battery is spread across each seperate clump of resistance in the circuit

in proportion to that resistance

for exmaple

a 10 volt battery
across a circuit with two 4 ohm resistors , you will measure 5 volts across each resistor.

if you had a 4 ohm and an 16 ohm resistor
you wouldd measure 2 volts across the 4 ohm
and 16 volts across the 8 ohm

becasue the voltage is split across those resistances in a 4:16 or 1:4 ratio

in your case some of your battery volts is across a junction in the circuit rather than across the igntion

Current in a series circuit is the same everywhere you measure

current is measured by putting a meter in the circuit, the meter has no resistance, and becomes part of the circuit to measure flow through it.

voltage is measured as a difference between a point on 1 side of a component or thing in the circuit, and the other side.
Volt meter just checks the difference between one side and the other

you do not break a circuit to apply a meter to measure voltage

measure the voltage between the incoming wire to the bulkhead connector and the outgoing wire in the same circuit, with the connector connected, to see how much you are loosing at that point.
should be close to 0, if its anything more your have a resistance at that junction that is causing a problem.

or just measure the resistance across that joint with the igntion off (depends on your meter) it should be 0 or very close

voltage is the push or the gradient that sends the current through. you shouldn't see any voltage across a junction, measurintg voltage across a junction indicates it is resistant.

resistance is the thing that tries to stops the current

there is no start and end to the current so its flow or value is dicated by the resistance in the whole circuit so current is sthe same where ever you measure in a series circuit.

parrallel circuits of which there are usually none in a car are harder

current is unique to the parrallel branch you meaure based on its resistance and the total supply current is a combination dictated by the combined resistance of the parrallel section.

Dave

Dave-R · Post by **Dave-R** » Tue Dec 03, 13 10:08 am

Stu Twin wrote:I'll go out 1/8 turn each side (at a time) and see if that helps.

Tune to JUST get max vacuum or rpm.

And then i'll see what the timing is. Think it was 14 BTDC from memory.

Not enough.

MilesnMiles · Post by **MilesnMiles** » Tue Dec 03, 13 10:10 am

When all else is sorted, the convertor could still be the problem. When I first got my Roadrunner there was too little stall in what was a mismatched combo. No amount of tuning would stop it stalling in gear.
That said, I note you could drive yours in reverse whereas mine would stall unless I two footed it in any gear.
New convertor and proper tune sorted it out.

Dave-R · Post by **Dave-R** » Tue Dec 03, 13 10:23 am

If you are not making enough power at idle due to being too lean or not enough timing then that will make the converter seem "tighter".