hello to everyone, i have been using this forum for quite a while and until today i have been able to obtain all the info i could ever want (and more), without ever having to post a question.
anyway, my most recent problem is that i have no spark all of the sudden.
since almost all bolt on parts are new i started with the most common areas of distress, and started switching out the warrantied parts. right now i stand with a new control module,coil,and complete distributor, wires, plugs, and cap/rotor are also pretty much new. this is a 77, f-100 with a 351m, fresh rebuild with the basic bolt on upgrades (alum manif, edelbrock carb, headers,mild cam ect...)
any help would be greatly appreciated, sorry if this is a repetitive post but im kinda tired of searching archives.

 

Did you have a starting problem before you started buying and swapping parts ?

What colour it the grommet on that Ignition module ?
It's the resin that holds the wires to the box.

Let's hope it is Blue

Have you CLOSELY inspected all the connectors that you touched for frayed or broken wires as they enter the connector ?

 

originally when i first put the motor back in the truck i did have a problem; with the resto i figured that since i was replacing the dist, i would go ahead and make sure everything else was up to par since the truck sat for so long and the parts were inexpensive. all the parts are oem/motorcraft, i usually opt for the "better" warranty to elieviate headaches later, since i will never be getting rid of this truck.
anyway, i have chased everything down, checked all wiring and connections, have power at the coil, have correct power at the connection for control module ect... thats why this seems to be so confusing??? it just happened out of the blue...

 

You never answered the grommet question

It's important

 

sorry, the grommet is blue...

 

BTW Pardon my manners, I usually welcome people to the site right from the "get go "

Welcome to FTE

Topic:
Well it's possibly the pickup module in the distributor.

Have you checked the secondary circuitry ......starting at the coil ?

Maybe hook up a tach to Test distributor to coil output.

 

picup module and distributor are brand new, just exchanged them today as 1 unit, i thought of this earlier and the part was warrantied.
what do you mean by secondary circuitry? how would i hookup the tach to test the distributor to coil output?
i know this has to be something small and stupid, i got a feeling that something was simply "missed" when checking all this out, but i keep checking, and since i know that all the parts are new it just gets me frustrated and i gotta walk away for awhile. Ive never had this much trouble with this before, usually its the module,coil,or picup....

 

i already have a tach hooked up normally but im not sure what you mean by using it to test the dist output, do i need to switch some of the wiring around for that? or is there just a way to check it the way it is? when you say secondary circuitry starting at the coil are you referring to the harness that runs from the ICM to the coil and dist? because i have gone over that harness from one end to the other(more than once).

 

Try a test for spark at RUN. Do it this way:

Remove the coil wire from the distributor cap.
Remove the distributor cap and set it aside.
Make sure one of the vanes or blades on the center shaft is at or near the face of the pickup module.
Now, use a screwdriver or similar metal to check for spark at the coil wire - and don't get bit.
With the ignition switch turned to ON or RUN, grasp the rotor and rotate the vane back and forth across the pickup face. There is enough play in it to do this. This should generate a spark each time the vane passes in front of the pickup face.
You may find it necessary to rotate the distributor slightly to get the vane in just the right position. (Turn the engine over by hand, with a socket on the crank if necessary.)

If you get spark, then there is something wrong with your electical hookup for the START spark energizing circuit.
If you do not get spark after trying this in several slightly different positions, then you need to look deeper yet.
I would suspect wiring issues, such as fried fusible links, broken wires inside connectors or the like.

Good luck, and stay with it. Even though these problems are really hard to run down, you will find it eventually.

Edit: Try removing the TACH just in case it is bad and causing a problem.

 

The primary circuit of the coil is the 12 volts at the + terminal of the coil.

The secondary circuit of the coil is the 15,000 volts that is sent to the distributor for distribution.

You said you had 12 volts at the coil (primary circuit)

Now we have to figure out of there if the secondary circuit (the 15,000 volts) that goes to the plugs is present.
The basic principle
The 8 vanes inside & on the distributor shaft turning breaks the plane of the pickup module which then sends feedback to the ignition module thus exciting the coil to send the large voltage from the center terminal of the coil to the distributor and eventuall to each spark plug.

Basically we are looking for power & the interruption of the power to the distributor.

The tach installed in the truck is not as good as an handheld analog tach that can be read at the coil when just cranking the engine in a no-start scenario

Banjo picker has given the instructions for a more in-depth visual way which works very well in an unlit environment.

 

ok, that was a good idea, but i hate to say that i still have no spark. i just dont understand, i have power at the coil, dist, and control module. everything wire wise seems to be fine. i guess i will just start chasing wires again. i just wish i knew a better idea of where to start, instead of just going at it blind..

 

Take the ignition control module to the parts store and have them test it ...while you're in rest mode.

Just cause it's new doesn't mean it's good.

you have checked for the rotor turning while the engine is cranking ...correct ?

Dist gear pins have been known to shear off .

 

Going to go ahead and do that, this is just way too frustrating, it HAS to be something like that. i have gotten bad parts off the shelf before, its just that when you know that the parts are only days old,you hate to keep making those trips to the store. besides.. i feel like they think im scamming them or something because i just exchanged the same part 2 days ago.. oh well, thanks for the advice, i think im gonna take it back to basics and start switching parts again...

oh, and yes i did check for the rotor turning..

 

Did it all again... switched the coil out, wasnt it, switched the whole distributor out,wasnt it, had the control module tested twice at 2 different stores and it checked out good; i have no clue what the heck this could be, i have never in my life had this much trouble with a spark problem. ANYONE WANNA BUY A 77 SHORTBED, 90% RESTO COMPLETE?????

 

This can be very frustrating, I know. Been there, done that, wore out more than a few T-shirts doing it.
All right, try these:

1. Can you double check that the collar on the coil is correctly installed? I don't think it is possible to install it backwards, but one never knows. Make sure the BAT side is truly on the battery side of the coil; it should be marked. Make sure the contacts are fully and properly engaged.

2. Can you check the ground? On the 4 wire connector at the brain box, on the back side of the connector (that is, between the connector and the box), you should have continuity between that wire and ground. This black wire grounds through the distributor. If not, then double check grounds between the distributor and the block, block and frame, block and cab/sheet metal, frame and cab/sheet metal.

3. Did you take the tach off just to make sure it isn't fouling things up somehow?

4. Use a jumper wire from the battery to send a full 12 volts to the wires below.

First, on the 2 wire connector at the brain box, jumper 12 volts from the battery to the RED wire coming out of the box (between the box and the connector). With the 12 V jumpered, see if you get spark. (I often use a sewing pin to pierce the wire, and then hook to it an alligator clip.)
If you do, then jumper the 12V to the other side of the connector, and try again to check the electrical connectivity of the connectors.

Second, if you do not get spark, ADD another 12V jumper to the BAT side of the coil, and try again.

If you finally get spark, then you have some power supply problems somewhere.

If these don't work, post back. I am hoping this test will reveal that although you may have voltage to the right spots, it may not be enough, or provide enough amperage.

If you have an e-mail address, I can send you a picture of the wiring setup. It may help you trouble-shoot it.