No spark when cranking

[Kemosobe]

A friend recommended you guys, I have looked over your tech articles and they are great, but still can't figure out the cause of my problem. I have recently purchased a 1977 Mustang II with a 2.8 V6 and automatic. It has sat for 6 years and wants to run, but will not start. I have a spark tester installed in line to a spark plug, occasional spark at start and end of cranking, but no spark during cranking. Any ideas apreacheated. I need the car out of the shop today so I can get another in for work and wife does not want to get in dirty old car on mothers day while I pull it out with Ford truck. Thanks in advance.

 

[RonD]

Run a jumper wire from battery +, to "+" on the coil, try to start.
If it starts remove jumper and see if it keeps on running.

On engines with distributor and single coil there is a START circuit and a RUN circuit for coil power.
This is because if you run a coil full time with 13+ volts(alternator voltage) it will burn out faster, on the RUN circuit there is a "ballast resistor" that will reduce the coil voltage by 5 volts, so coil "runs" on 7-9volts.
But you want full voltage when starting the engine cold for a hotter spark.

There were a few ways to do this dual voltage system.
If the starter relay(on fender) has 4 posts then the "I" post will run to the "+" on the coil, when starter motor is turning this sends 12volts to the coil, but only while starter motor is turning.

On the ignition switch there is a separate RUN and START circuit.
In START position 12volts is sent to starter relay AND to coil, but not to other electrics, like heater fan, this allowed all battery power to go to starter motor.
In RUN the ignition switch sends power to all electrics, except starter relay, and the 12volts to coil now passes thru a "ballast resistor".

Here is a diagram and troubleshooting guide of the 2.8l Ranger ignition system, a TFI system:
http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

If you look at the TFI module on the distributor you will see separate START and RUN connections, test those

 

[Kemosobe]

Thanks Ron, I am headed out to the shop to try it. I'll let you know.

 

[Kemosobe]

It runs

Runs well and drove out of the shop, thanks Ron. A more detailed post after Mothers Day dinner.

 

[Kemosobe]

wrap up

Thanks guys, "need urgent help fast" worked terrific. Car had not run for 6 years and I could tell it wanted to start, but something was amiss.
Ron, ran jumper as you suggested and pulled wire when started. Engine died when wire pulled. With jumper connected we heard static bubbly noise from distributor with engine not running and ignition on. Noise either goes away or can not hear it with engine running. Engine starts and runs fine with jumper hooked up.
Full disclosure: I bought this vehicle to use the powertrain in a street rod project. I do not like this distributor and ignition module set up. Is there another distributor that fits that may just have points and I could add a Pertronics unit too? Thanks again

 

[kimcrwbr1]

Sounds like a faulty ignition switch to me the duraspark is a very reliable system. Do not run it with the coil jumpered as it requires ballast voltage around 9 volts. On the two wire connector for the ignition module check for battery pos key on red wire and the battery voltage key on start on the white wire. That is a 37 year old switch if original? The white wire actually retards the timing for a quick start.

 

[RonD]

Yes ^^ +1, you need to find the problem with the system, the jumper is for temp use.

This site has good wiring diagram for Duraspark: http://www.wrljet.com/fordv8/duraspark.html
It is worth fixing, I don't think they make a Ford 2.8l compatible GM style HEI distributor, which would be the only other alternative I would consider an "improvement".

I think Mallory makes a dual point distributor with vacuum advance that will work on the Ford 2.8l.
I know it seems "better" to go back to points, but it really is a step backwards in reliability.
Like carb vs EFI, EFI wins hands down for reliability.

In any case you need to track down the voltage issue from ignition switch to distributor/coil, you will need that working with any spark system you decide on.


EDIT:
I read your only using the drive train................so in the finished vehicle just use the 4 post starter relay(tractor relay) with the "I" post(they are cheap), and a Ballast Resistor on the ignition switch Run wire to "+" on coil.

Wire from "I" post to "+" on coil.
Wire 12volts from ignition switch to Ballast Resistor, from Ballast Resistor to "+" on coil.

 

[Kemosobe]

RonD, sorry for not getting back earlier. I read your last post and have been behind on computer stuff lately so haven't replied. Using the wiring you mentioned, does this eliminate the ignition module? I don't think it does, just trying to confirm. Thanks

 

[kimcrwbr1]

In 1974 for one year they did make a points ignition for the 2.8. The mercury capri and the mustang other than that you have only two choices the duraspark module or the 4 wire GM module can also be used.
http://www.ebay.com/itm/ACCEL-35361...Parts_Accessories&hash=item2c81b37be7&vxp=mtr
This is also a very dependable ignition used on any reluctor type distributor.

 

[RonD]

RonD, sorry for not getting back earlier. I read your last post and have been behind on computer stuff lately so haven't replied. Using the wiring you mentioned, does this eliminate the ignition module? I don't think it does, just trying to confirm. Thanks

No it doesn't, it just gives 12v to the coil, the coil still needs to be "told' when to spark.

Just a quick note on spark systems.
Gasoline vehicle ignition systems have worked the same way since........well forever.
An ignition coil is a voltage amplifier, it takes low volts/high amps and converts it to high volts/low amps.
To get a coil to release a spark you cut power to it, then repower it and cut power again to get another spark, ect.....................
Because of the "positive" wiring in vehicles the Ground is easier to use to cut power than cutting the 12v side.
For 70 years "points" were used to do this, the points are connected to the "-" on the coil and a Ground(distributor housing).
The coil is given 12volts all the time(key on)
When points are touching coil powers up, when points are separated power is cut and coil sparks.
There are lobes on distributor shaft to open and close the points creating the sparks and rotor on the top to send the sparks to individual cylinders/spark plugs.
The downside of mechanical points is that they wear out and need to be cleaned/filed and reset, and then replaced when they wear down enough.

"Pointless" ignition systems still used a distributor and rotor but used a "sensor" to detect the "lobes" and "transistors" as the on/off switch for the "-" on the coil.
Most of these were a big improvement because they didn't need the attention mechanical points did.

The coil itself never changed during this conversion, and it has one weakness, heat.
A coil is just what it's name says............a coil of wire, well actually 2 coils of wire
Now if you have ever looked at an electric heater or inside an electric toaster you will see a "coil" of wire, when you apply voltage to that coil of wire it starts to heat up, and that's what happens inside an ignition coil.
The more voltage you apply the more it heats up, so with less voltage it heats up less.
This is why a "ballast resistor" or "resistor wire"(GM) is used to lower the voltage at the "+" side of the coil, coil can still spark well enough but will run 50% cooler.