No spark. Why?

MilesnMiles · Post by **MilesnMiles** » Sun Dec 11, 16 11:34 am

Drove my RR home last week, no problems. This week it will not fire.

I have done the following wiring changes. Can anyone spot what I might have done that could have affected the ignition circuit?

Fitted new alternator. Fitted new charge wire from back of alternator to battery live.

Changed batttey and terminals. Reconnected al lives and earths.
Car spins over but refueses to fire. Had Partial backfire (I thought) yesterday and assumed a flooded condition.
Tried again today and no fir up. No spark apparent at plugs.
I changed the ECM for a spare. Still no spark.
Does the main red feed from batt live to starter solenoid have any effect on sparks? I don't believe it does, but I need advice as I'm stumped.

ANTON · Post by **ANTON** » Mon Dec 12, 16 7:28 am

Do you have a rev counter.
If you do disconnect the sensing wire off the coil and try again.

Check for 12v power at the ballast terminal with ignition on.

Try turning ignition on and then use a screwdriver and sort the starter solenoid and see if it starts. If it does then there is an issue with the cranking live at the ignition switch.

Dave999 · Post by **Dave999** » Mon Dec 12, 16 11:55 am

does yours have a 3 wire starter

fat wire is power

1st thin wire is solenoid trigger (12 volts)
2nd thin wire takes 12 volts from the solenoid trigger and a think sends it back up to the ballast to give 12 volts on start.

by pass the ballast with a loop of wire and see how you go

if it starts then the ballast or the wire feeding it is at fault

don't run for long with ballast bypassed unless you have coil and ECU that can handle 14.6 volts all the time

Dave

MilesnMiles · Post by **MilesnMiles** » Mon Dec 12, 16 12:08 pm

Thanks Anton/Dave
I'll try the tach trick, just in case.
Going back to Saturday I think the car was trying to start as the key returned to the off position. That would make the ignition circuit the issue I guess.

Can I not run a live from coil + to batt + and then start the car to cut out ballast and ignition circuit?

Also, I saw a yank forum that suggested removing (temporarily) the field wires from the alternator as this can sometimes cause problems if the alternator (brand new) has a diode issue. Heard of that one before?

Dave999 · Post by **Dave999** » Mon Dec 12, 16 12:35 pm

Ok the symptom you describe indicates the following

ignition key in run position = spark
ignition key in start position = starter motor but no spark

so you problem is power to coil when key is in the start position.

perfectly ok to wire coil to battery +

just keep in min it won't stop until you disconnect

and if you leave it connected when stopped you can burn stuff out

Dave

Dave999 · Post by **Dave999** » Mon Dec 12, 16 12:40 pm

neutral danger switch?

you know the one that stops you starting the car when you stall it halfway across the railway lines, big puddle or river

Dave

Scooby · Post by **Scooby** » Mon Dec 12, 16 12:43 pm

Miles welcome back to Mopar ownership

MilesnMiles · Post by **MilesnMiles** » Mon Dec 12, 16 12:50 pm

Welcome back indeed. Buy car, car wont start..
Hi Dave, got you on that.

Something further to consider if you can.
On the drive back from collecting the car (45 miles) the main charge wire from the alternator broke off (fatigue) and therefore for some or most of that journey I was running on just battery power.
Could that put to much stress on electrical components?
I've just ordered new coil and resistor anyway.

Dave999 · Post by **Dave999** » Mon Dec 12, 16 3:49 pm

not really

when you run the car on the alternator (most of the time) the regulator will maintain 13-14.5 volts at the battery +

it basically flows out current to a level where everything that is switched on and consuming current is getting the current it can flow.

that includes charging the battery

the current anything can flow is limited by its resistance

and when you are flowing enough current to get everything to the max the regulator looks to see that the voltage at the battery is maintained at 14 or so volts

so your electrics see anything between 12 and 14 volts as the regulator goes off and on maintaining the flow of current

what could have happened is the ballast (4 pin I guess) has died in the start position but not in the run position for no other reason than age

in run you are just sucking current from the battery through 1 side of the ballast to the coil and then to earth and all you are doing is switching it off and on to a nice rhythm dicated by your Dizzy

the fact that it was 8-12 volts for the drive home not 14 should make little difference to anything other than the alternator and regulator circuit.

they will have been going mental trying to up the voltage at the battery as it decreased over time

and to no avail because the battery wasn't connected to the output of the alternator.

when you get it running

check voltage at alternator output stud

it should be north of 13 volts with the engine above 1000 rpm

then switch on headlamps and watch it dip and return to 13+ volts

that should indicate that the alternator as doing something useful.

things to think about

1) your regulator usually only spits out 5 volts into the coils in the alternator for 5 minutes or so until the battery makes up the charge it used for starting. on yoiur drive home it did it continually from the point of breakage
2) your alternator only works at full capacity when you ask it to. and you asked it to continually work at full capacity for the drive home after breakage..... it wouldn't normally do this unless you run massive electric fans electric water pump have the lights on wipers heater and a thumnping great stereo

however the current it produced had nowhere to go. so it might have got a bit hot

and i'll guarantee that your fuel consumption will have been up as a fully ON alternator robs a decent chunk of power because it is so stiff to turn.

they are rarely fully on to max capacity unless you over leoad them with stuff to run then you notice it is under rated cos your lights dim with the bass on the stereo and when you switch on the heater fan.

Dave

MilesnMiles · Post by **MilesnMiles** » Mon Dec 12, 16 7:06 pm

Dave, thanks so much for the explanation, really helps me understand. I'll take. A proper look over xmas. At least I will have new battery, alternator, coil and ballast.
I even have. A spare ignition barrel somewhere in a box.
Took the Fox out for a blast tonight. It was lovely

latil · Post by **latil** » Mon Dec 12, 16 8:28 pm

Put the Fox on ebay and apolgise to your Mopar,it will then mysteriously run again

MilesnMiles · Post by **MilesnMiles** » Mon Dec 12, 16 8:47 pm

Steve, it's on eBay! And still the Mopar is sulking. Ungrateful heaps of nuts n'bolts.

Dave81 · Post by **Dave81** » Tue Dec 13, 16 1:49 pm

MilesnMiles wrote:Steve, it's on eBay! And still the Mopar is sulking. Ungrateful heaps of nuts n'bolts.

Well you did sell her.......These cars have a way of getting back at you (just like women)!

She wont be happy until you bin off the foxy mistress and start the blood seat and tears again of working on her again!

Every problem solved is one less to do...........That's what I keep telling myself!!

Adam · Post by **Adam** » Tue Dec 13, 16 2:15 pm

If it tries to start, but dies as soon as you release the key to the run position, I would suspect the ballast resistor. Easy enough to check voltage to BR at start and run (BR is bypassed in start position).

MilesnMiles · Post by **MilesnMiles** » Wed Dec 14, 16 11:14 am

Ok, it's not trying to start. No spark evident.
Today
Replaced the ballast resistor and coil
Then hot wired a wire from batt pos to coil pos. cranked it via the started studs (cut out ignition) still no fire