bluemax500

Hi everybody, I'm a new poster, but a bit of a troll when I'm looking for answers.
I've been driving my truck for about a decade. It's an automatic 1978 F150 Custom, with a 351W engine. About a year ago it started having stalling problems, it would get me to work and not get me back home. I replaced the ignition module, thinking that it was just heating up and failing, but it didn't fix my problem. I took it to the mechanic, and they told me it wasn't an easily replicated issue and that they couldn't tell me what the problem was, but they replaced my spark plugs, spark plug wires, and distributor cap for good measure. Of course on the way home from the mechanic, it stalled for the first time while driving, and I had to leave it overnight. The next day I walked back and was able to start it back up again. I took it right back to the shop and made them drive it around until it stalled on them, and they told me that I needed a new distributor, so I said thanks, and replaced the distributor myself, set the timing, it was running beautifully, so I drove it around town, but then on the highway when I got it up to speed, the engine begin to struggle and then stalled completely. My dad thought it might have settled in while driving and rotated a bit, but I don't think that's my issue. I've since taken out the distributor and reinstalled it again, and once it again it was running beautifully, but after driving only several blocks, the same thing happened again and it started to struggle, the alternator light came on, and then died. The distributor is still down tight, right where I set it. The engine will turn over, and even start running, but I can only seem to get it to struggle for a few moments before it dies again. I checked my fuel filter, and it's just about brand new. I'm getting gas in my carb, and I'm kind of starting to run out of ideas. My dad (who used to be the owner, and it's long-time mechanic) is brainstorming with his buddies, and has suggested that it's maybe the coil beginning to fail, or the fusible link, but I thought I'd post here and see if anyone might be able to shed some light on possible culprits here.
Thanks!

Good old Bill

Am going to ask more questions than offer the miracle fix. Ignition module replacement, that refers to the dura spark module and did you install the same colored mold that was original, assuming blue? Have you verified spark at the plugs during this shut down? Is there fuel visible with the accelerator pump during this shut down? Ideas, if the module was the same color as original, (hopefully Ford OEM) and there is no spark, check for power at the + side of the coil. If there is power to the coil then need to check its trigger. If no power then go to the ignition switch and check there. On the other hand if there is no fuel at the accel pump, then check for fuel at the inlet. Basically we need to fine out if its electrical or a fuel issue.

bluemax500

Thanks for the reply, Bill. I've tried several ignition control modules from a couple different places (Autozone, and Schucks), but all three new ones I've gotten are black on the underside, I'll have to double-check when I get home, to see if the current one is blue or not, but if the parts store produces a black one when I ask for one to fit my truck, how do I go about getting the right color? Am I just going to need to get a ride to the wrecking yard?

Good old Bill

Need to ask the ford dealer which is the correct module. Should be an engine calibration code on the door. Remembering 5 colors, white, blue, red, yellow, and black. Don't know what the diference is. Again need to verify if its fuel or ingition?

bluemax500

So my new control module looks like it's the same color as the old one. I don't think it's a fuel problem. I think the accelerator pump is working fine, and I get gas in the carborateur. There was a tear in the vacuum hose going into the front, top of my carb, almost directly above the fuel filter, so I'm going to replace that, and check my coil, I guess.

Good old Bill

Again need to find out if its fuel or igition. When it stalls again, pull a plug wire, insert screwdriver and check for spark. If spark is present then check for fuel via the accelerator pump. I need this done during the no run condition in order to help out. If my tone seems short, please excuse me, still upset due to road rage, and I wasn't even the drivers involved.

bluemax500

I probably forget to mention. It doesn't want to start again. The last time it stalled it didn't start again until after I'd tried replacing the distributor, thinking that it had settled or something while running and skipped timing. Last time I was 99% sure the distributor hadn't moved on me, this time I'm 99.99% sure that it's still in the same place. I'll check for spark, but the accelerator pump is definitely causing fuel to spray into the carborateur, in it's current non-starting condition.

No worries, any help is better than no help.

Good old Bill

Being a 78 it has the DuraSpark ignition, you have changed the distributor with the pick-up coil inside, and you are right it hasn't moved, the other half of the primary side of the ignition is the module itself. Usually mounted on the fender well. Its a 5" square thing about 1 1/2" tall. Has two connectors (I think), indicators of going bad, very temperature finicky.

bluemax500

So the coil is inside the distributor?

I've already tried swapping out the ignition control module several times, they've all been the same color as the original, and they haven't made any noticeable difference.

Good old Bill

Go to the actual ignition coil that has the high tension coil wire to the distributor. With test light see if there is power at the + terminal. Then go to the - terminal and see if the light blinks while someone cranks the engine over. If both conditions are met and still no spark the actual ignition coil is defective.