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My research tells me this is a vacuum related SOMETHING under the dash. I chased the vacuum tubes from it, and they went through the firewall, and about 12" of each were in the engine compartment, but hooked to nothing. SO, to clean it up as it wasn't being used, I pulled the tubes through the firewall, and just busted em off at the box. (I have an hei distributor w vacuum advance self contained). Could be coincidental, but now the truck cranks, but won't fire. Removing these vacuum lines is the only thing I did since trying to start the truck today.
First what are we working on and is it a Cali truck needing to pass smog?
Are you sure they were vacuum lines and not wires?
I don't see a lot of it but they look like wires.
why would they run vacuum lines to a box inside the cab?
So check the basic dose it have spark and fuel?
Dave ----
Apologies. It's a 1970 f100. 302 v8, c4 auto, 2wd. I'm in NY. No smog worries. I'm attaching a diagram I found on a different site. The discussion there led to being able to delete it completely as it was an added system, and not part of the factory harness. It also stated that this was only installed on 70 and 71 f100 trucks. F250 and up were exempt because of their gvw.
That it was inoperable before lends me to believe it has nothing to do with my non starting issue. I haven't had time to go out today and even begin testing for spark etc.
HEI cap and rotor contacts needed cleaning. Read 12v at power to the coil (cap) w the key on. In line spark indicator showed no spark after the cap.
I also completely removed the system in the diagram above, unplugging it from the two connections under the dash. Nice benefit of that is I gained a nice 12v, key on power source already there w a female plug end to use in the future 👍
I dont know what that is your opening pic. Did your truck come with the HEI distributor? If so, does it have the resistor wire deleted or does it use the in-run power as a trigger for a relay to the HEI?
I got the truck with the HEI, but it would have come stock in 70 w coil and distributor. Right now there is one wire (12v power) going to the hei, and it is one wire of three that are in a loom headed in that direction. The other two are just cut and taped off. Can't recall the colors right now.
My original picture of the "black box" is explained in this diagram. Electronic control module and solenoid valve.
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If my memory is correct that was the module that controlled the vacuum advance after the transmission shifted into high gear. I used to have to jack up the rear wheels and run it up at Dad’s shop to check if the vacuum advance system was working after a tune up.
So what ever that was it is no longer.
You just made the truck lighter for racing I meant better MPG LOL
So you have HEI distributor did this run before?
If so pull the cap and rotor and check the rotor for cracks or spark burn thru.
If you pull the top cover off the coil but leave everything else in place you can do some checking with a test light.
Make sure coil is getting power on its connector.
Find the coil ground and make sure the coil body has a good connection. I seen posted some coils are painted and dont ground well.
I think you can put a test light on the tach connector and see it flash when cranking is not no spark.
Dave ----
The other two wires should be red/wht and wht/red. They are for oil pressure and water temp but off hand I dont remember which is which.
Originally Posted by kenny nunez
If my memory is correct that was the module that controlled the vacuum advance after the transmission shifted into high gear. I used to have to jack up the rear wheels and run it up at Dad’s shop to check if the vacuum advance system was working after a tune up.
Originally Posted by FuzzFace2
So what ever that was it is no longer.
You just made the truck lighter for racing I meant better MPG LOL
So you have HEI distributor did this run before?
If so pull the cap and rotor and check the rotor for cracks or spark burn thru.
If you pull the top cover off the coil but leave everything else in place you can do some checking with a test light.
Make sure coil is getting power on its connector.
Find the coil ground and make sure the coil body has a good connection. I seen posted some coils are painted and dont ground well.
I think you can put a test light on the tach connector and see it flash when cranking is not no spark.
Dave ----
Thank you all for the help! She's running like a top now. Cleaned the cap and rotor contacts and it kicked right off 👍 Today's mystery, is non working spedometer all of a sudden during todays outing (first was, and then was not woring), aand my brake pedal feels stiffer than normal. Just another day driving an old truck. I love that it keeps my busy haha- The brakes work really well, just the pedal feels harder than normal.
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