Shelby Not Running

If it jumped far enough, and the cap diameter is big enough, the coil could be firing with the rotor so far away from a contact that the spark goes nowhere.

Kenny_McCormic wrote: If it jumped far enough, and the cap diameter is big enough, the coil could be firing with the rotor so far away from a contact that the spark goes nowhere.

nope.. the magnetic pickup in the distributor only allows the coil to fire when the rotor is pointed at a terminal in the cap.

I would even if timing chain jumped or stretched, I would still be getting spark at some point. I can crank the engine over and over and get no spark at any plug.

Let's assume that the timing chain jumped. If I cranked the engine for a period of time, shouldn't number 1 plug fire at some point, even if it is firing out of sequence with the valve train?

Is the auto shutdown relay good? It wouldn't be the first time I've seen a late '80's Mopar have the ASD relay fail and keep the vehicle from starting.

Rob, you must be a mind reader because I just stumbled upon a spate of problems Dakota owners have had with ASDs. I am going that rought next.

Rob, doesn't the ASD also shut down the fuel? I am getting fuel out of the injectors.

Also, where is it located on the Shelby Dak?

I am looking at a diagram of the engine compartmnent and it does not list an ASD. There if a fuel pump relay, but I am getting fuel.

Is the fuel a steady spray? Maybe just residual pressure in the system from the key-on priming of the electric pump?

Had a Daytona parts car once a buddy talked me into selling to him for a beater. ASD relay drove us nuts for a few days on that one. IIRC, the pump would pressurize the system at key on, but the relay would kill it when trying to run. Engine would crank its brains out.

On your Shelby, I think all the relays are mounted to the driver's inner fender, toward the firewall. I don't remember there being any relays near the ECU on the passenger inner fender. I think there's a bank of 4 or 5 there. Should be the ASD, fog lights, electric fan, and maybe the fuel pump? Something like that.

I don't have the hood bolted to the hings on mine right now or i would take a look when I get home. Somewhere at home I have the service manual from my old '88 Sport. The relay location should be the same. I'll see if I can dig it up.

It was the coil. I popped in a cheap Advance Auto coil and it fired right up. The old coil (a 18-month old Accel Super Stock which has less than 200 miles on it) was making power, but was too weak to overcome plug wire resistance.

Congrads!

I gave up on the Accel coils. Just pulled the year old one off Erin's Challenger. Would quit after running about 20 minutes. Tossed the Barracuda's 12+ year old MSD coil on it and it's happy. Barracuda is running a Pertronix now, but I didn't have a spare one of those handy at the time for the Challenger.

So now post some pics of the freshly painted truck.

nope.. the magnetic pickup in the distributor only allows the coil to fire when the rotor is pointed at a terminal in the cap.

You do realize that there are cars with distributors where the computer triggers spark in a ~40 degree range? Meaning the rotor can be and is 20 or more degrees from a terminal when it fires, at times. All the pickup does on a non-mechanical advance distributor is tell the computer where the engine is. The computer has total control of when it grounds the coil.

Vigo wrote:

nope.. the magnetic pickup in the distributor only allows the coil to fire when the rotor is pointed at a terminal in the cap.

You do realize that there are cars with distributors where the computer triggers spark in a ~40 degree range? Meaning the rotor can be and is 20 or more degrees from a terminal when it fires, at times. All the pickup does on a non-mechanical advance distributor is tell the computer where the engine is. The computer has total control of when it grounds the coil.

yeah, and you do realize that sometimes they still work even without the ecm being functional, altho there is no advance of any kind- 80's carbureted GM vehicles are an example of this.

also, it won't fire "within 20 degrees" of lining up with the terminals.. the terminals are wide enough that it can fire within however many degrees of the center of the terminals- sometimes upwards of 25degrees before it is centered if you have 50 degrees or more of advance at cruise or whatever for efficiency..

in this case, he said he was getting a spark, but it wasn't getting to the plugs for whatever reason (turned out to be a weak coil).. something was telling the coil to fire- and that won't happen unless the distributor is doing it's job and telling the coil to fire when the magnetic doohickies line up..

Before

After

The truck is for sale.

"something was telling the coil to fire- and that won't happen unless the distributor is doing it's job and telling the coil to fire when the magnetic doohickies line up.."

Sure, except that the distributor does not tell the coil to fire on this vehicle. Other than that crucial detail i would have agreed with you in the first place..

And obviously my quote button stopped working for some reason.. lol

Vigo wrote: "something was telling the coil to fire- and that won't happen unless the distributor is doing it's job and telling the coil to fire when the magnetic doohickies line up.." Sure, except that the distributor does not tell the coil to fire on this vehicle. Other than that crucial detail i would have agreed with you in the first place.. And obviously my quote button stopped working for some reason.. lol

something tells the coil when to fire- and the distributor has something to do with that, even if it's not done directly.

"something tells the coil when to fire- and the distributor has something to do with that, even if it's not done directly."

Yup, the Hall-effect pickup.

But unlike whatever GMs you were referring to, if the computer isnt working, the coil wont either.

Ive replaced computers in 80s dodges that had bad coil drivers and nothing else wrong with them. The distributor was telling the computer whatever it damn well felt like and it didnt matter since the computer couldnt fire the coil.

Vigo is correct. The early Mopar TBI and carb computers were first and foremost spark computers.