a friend of mine has a 5.0, pertronix dist, stock coil. when he removes the...tach wire...from the coil, engine dies and will not crank untill wire is reinstalled... he has replaced...alt (twice) dist/mods 3-4 times and 3-4 coils from being burned out... ...any ideas...
won't fire a lick...without the tach wire hooked up. he has replaced the coil and it run for 15-20 mins. and then burn the new coil or dist. mod. out. replace dist. mod. and it runs a few mins. then burns dist or coil out again...
In my tiny brain it almost sounds like it is grounding through the tach but you would think it would burn the tach up first? Just because all the wires are hooked up don`t mean they are all good I have seen them break off in the sheathing but still look like a good wire on the outside.
what wire/wires are you refering to? does a coil have a ground wire? I thought it grounded through the sparkplugs... ..12v...coil...dist...sparkplug...head...
I can see it not running if it were grounding through a bad tach being hooked up but to not run with it...unhooked...
Spark plugs ground to block..... block grounds to frame....... frame grounds to battery. I was thinking like Elliot at first also. might be a bad ground somewhere. Is there a ground from the block to the chassis? and is it making good connection? Thats probably too simple of a solution to be the problem. Now we are back to checking voltage to the coil like the problem Earl was talking about last week. Check the coil and see if its an internal resistor coil he is using or if it needs an external resistor. Then check the cars coil wire and see if its original and has the resistor wire or if its now full 12volts.
Yeah, Rusty, it is an '86 5.0L with a T5. The thing was running fine, and then started burning up coils and distributor modules. I did fine a skinned stator wire on the alternator that was touching the alternator body, but I have to go into the harness and find where it goes, as I don't have an indicator light, just a gauge. I'm almost afraid to put in the new distributor and coil, until I find what is going on. As for the tach, who the H... knows. I guess disconnect it and then get the engine started and work from there. Wish me luck!
I wish you were closer, your problem is intriguing (unfortunately). It is hard to help diagnose over the web... You will get it, these cars are simple machines, just gotta figure it out.
The coil primary winding is grounded by connecting the (-) terminal to the Pertronix module. When the module turns on it grounds the coil primary winding and builds the magnetic field in the coil. When the module turns off the the primary winding becomes an open circuit, the magnetic field collapses in through the coil windings and induces a high voltage to the secondary circuit (plugs). If it's an Pertronix I they require that the coil primary has a minmum 1.5 ohms resistance. Any less and the module will overheat. Also the module has to have a good connection to the breaker plate inside the distributor to act as a heat sink and provide ground. And check the little ground wire from the breaker plate to the distributor body.
Ok, in post #1 Frank said a stock coil was used (he is officially old now so I understand ). Do you have a stock or other distributor you can try? Sounds to me like that's where the problem is.
http://www.google.com/imgres?imgurl=http://www.customtacos.com/tech/files/tach_install/Tach.gif&imgrefurl=http://www.customtacos.com/tech/index.php?article%3D52&h=468&w=600&sz=18&tbnid=fASavL7Cq73yxM:&tbnh=90&tbnw=115&prev=/search%3Fq%3Dtach%2Bwire%2Bdiagram%26tbm%3Disch%26tbo%3Du&zoom=1&q=tach+wire+diagram&docid=SoD85AWdDhm84M&hl=en&sa=X&ei=K5-gT63xN8aC2wWr0YXfCQ&sqi=2&ved=0CDYQ9QEwAg&dur=2488 this mit help im not sure but it along the line to remove tach the red wire should be tie into the place of the green one
