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So this is my second time posting about this specific issue, the first thread seems to have been lost. I can’t find it. Anyway, I have a 78 351m that just won’t start. It started after we put new head gaskets, intake gaskets and valley pan on. The rear gasket below the valley pan blew out and caused coolant to leak into the oil. I replaced that, and the valley pan, and now after getting it back together the truck won’t start. I did take the distributor out to get the intake out, so I reset the timing. At first, it was spitting and burping out of the carb. Now, I’m getting some backfire occasionally out of the new headers I put on. But that’s about all. I honestly can’t find much in how to set timing, all i know is get it to TDC and drop the distributor in, so that’s how it’s “set” now. Timing may be my issue, but i have no damn clue how to fix that. I also don’t really have access to the tools to do so. My next idea was it may have been the voltage regulator, not allowing the distributor to cause a big enough spark at the plugs, so I replaced it. After a 2 second crank, the voltage regulator is so hot that I can’t touch it. Same goes for the negative battery cable.
You might have the distributor installed 180º out? You want the #1 cylinder at TDC on the compression stroke, (where you feel air escaping, with your finger over the spark plug hole when turning the engine over) and then you want the distributor pointing at the #1 terminal.
Another thing to check is the wiring to the Duraspark ignition module box. The insulation has been known to shrink or even flake off, leaving exposed conductors which, if they short circuit, will cause the engine to not run at all, or to run very badly.
And how are your battery and starter cables? If they're crusty, then it will be really hard on your battery and charging system.
If the ground is getting hot, then there could be too much resistance which means the coil probably isn't getting what it needs to spark ,,have you checked to see if you are getting spark while cranking at the plugs ?
If the ground is getting hot, then there could be too much resistance which means the coil probably isn't getting what it needs to spark ,,have you checked to see if you are getting spark while cranking at the plugs ?
I just got done cleaning and replacing fuel lines, thinking that was my issue because there was a TON of trash in them. Truck still won’t start. We just tested for spark and have nothing. I have no clue where to go from here though.
You might have the distributor installed 180º out? You want the #1 cylinder at TDC on the compression stroke, (where you feel air escaping, with your finger over the spark plug hole when turning the engine over) and then you want the distributor pointing at the #1 terminal.
Another thing to check is the wiring to the Duraspark ignition module box. The insulation has been known to shrink or even flake off, leaving exposed conductors which, if they short circuit, will cause the engine to not run at all, or to run very badly.
And how are your battery and starter cables? If they're crusty, then it will be really hard on your battery and charging system.
I re installed the distributor, and am now not getting spitting, burping or backfire, and I’m at TDC with the rotor pointing at number 1. Also, I’ve replaced the duraspark, did that a few months ago so it should be OK. also replaced the coil, and all the plug wires. The positive, negative, and starter cable are all new. I now have no spark though.
Recheck all the DSII box plugs and coil hook up to make sure they are in good shape.
The only other thing I could think it might be is the PIP pick up coil inside the dist.
Dave ----
The post will tell you how to test the coil an several things quicker than I could type it , and there is a resistor wire that could be bad or as in the case of the above post was a wiring issue
Pull the coil wire from the distributor cap and hold the terminal about 3/8" from a head bolt or good ground and crank the engine over. There should be a nice fat spark.
It is possible for a defect in the cap itself, the rotor, or wires, plugs, that are causing trouble. So if there is no spark from the coil wire in this preliminary test, we've narrowed it down at least some, to the coil, or primary ignition circuit, ignition switch. Process of elimination. It really helps to use a shop manual or repair manual because they list logical methodical troubleshooting steps.
Pull the coil wire from the distributor cap and hold the terminal about 3/8" from a head bolt or good ground and crank the engine over. There should be a nice fat spark.
It is possible for a defect in the cap itself, the rotor, or wires, plugs, that are causing trouble. So if there is no spark from the coil wire in this preliminary test, we've narrowed it down at least some, to the coil, or primary ignition circuit, ignition switch. Process of elimination. It really helps to use a shop manual or repair manual because they list logical methodical troubleshooting steps.
I’m attaching a picture of my distributor, but I’m fairly new to this so I’m not familiar with what any of the wiring/electrical parts are. If you could point it out for me, it’d be a big help. Same goes for basically everything else on the truck. Someone above said something about a resistor wire, and checking the duraspark for voltage or something and I’m not sure how to check either of those. The mechanics on this truck I have been able to figure out myself, because it’s stuff I’ve done before or that is straight forward. All of this electrical stuff makes no sense to me.
I would look back at wiring since you had the intake off as well, the wiring bulkhead under brake booster , start there as some wiring is in that general area near rear of intake and look for broken or cut wires ,,check the fuses closely ,,
Another good helpful post https://www.ford-trucks.com/forums/1...ere-is-it.html
As far as the resistor wire From the ignition switch: Follow the red w/green trace..it should lead you to a splice. The resistor wire should say "resistor wire do not cut or splice," 4' 1" long, 1.30 - 1.40 ohms resistance, 16 gauge wire. It may be pink/red. I think it leads to a brown wire to the 'I' terminal on the solenoid.
D7AZ-12250-A, Motorcraft DY 213. ('73 and later) Another possibility - D7AZ-12250-A, Motorcraft DY - 84 -A, 60" long, red w/green stripe, 1.30 - 1.40 ohms, 16 gauge. Thanks to NumberDummy. I may be wrong on the Motorcraft numbers....someone with more knowledge than me might be along.
I’m attaching a picture of my distributor, but I’m fairly new to this so I’m not familiar with what any of the wiring/electrical parts are. If you could point it out for me, it’d be a big help. Same goes for basically everything else on the truck. Someone above said something about a resistor wire, and checking the duraspark for voltage or something and I’m not sure how to check either of those. The mechanics on this truck I have been able to figure out myself, because it’s stuff I’ve done before or that is straight forward. All of this electrical stuff makes no sense to me.
Did you replace all them parts before or after you moved the dist?
If after you have gone and added a LOT of things that could be a cause and now made more work for your self.
I take it that red mark is where #1 plug wire is located? If so I am not seeing the dist. pointing to #1 or is it the picture but I am sure its not the picture.
I say this because the rotor looks to be to far off BUT THE BIG ONE ......... the star wheel is not even close on the pick up coil to fire.
Turn the dist. so the rotor lines up with your mark and the star is on the pick up coil.
Then check for spark like someone posted, coil wire 3/8" from motor block and tell us what the spark looks like.
Dave ----
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