I own the above truck (240 CID straight six) and recently detailed the engine compartment as well as cleaned up the wiring. Before this all was working fine. Regarding the wiring, I took extra care labeling all wires and connections so that when they were rerouted, lengths of damaged wire replaced etc. that the circuits would remain as they were. When it came time to start it up, I turned the ignition switch to run (dash lights on, accessories work) and then held the switch momentarily to start. The starter cranked and kept cranking even after I released the key back to the run position, turned it to off and still cranking. I had to disconnect the battery from the solenoid. Upon attempting to reconnect battery to solenoid shorting occurred. Something was grounding. I removed the battery's pos. lead and bypassed the solenoid and starter and applied it to all other power circuits and all seemed fine. Tried to connect the battery + directly to the starter and zapp, shorting (multimeter shows no resistance between starter lead and ground, direct short). My question, why did the starter at first crank - then not stop - then short on second attempt to apply power.
Also, It appears I have a electronic ignition system that does not seem to be stock. There is a sealed ignition module mounted on the wheel well with no markings on it whatsoever and an electronic distributor (type with six rotating magnets and a sensor) that only says "Motorcraft" on it, no other markings. This distributor is also the type that uses 8mm wires with a cap that has male terminals similar to a spark plug's. It is using a standard 12 volt external coil. Do you know the model of this unit and anything about it. Maybe installed as a Ford upgrade years later made specifically for this engine being that it's Motorcraft?
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Thanks for any help you guys can provide.

 

Not sure on this but I would think something happened to the starter solenoid or something got mixed up on the solenoid. I know I put the wrong wire to the small leads on the start solenoid and the starter just started spinning. That could have taken out the starter. Or the starter was on the edge and this problem pushed it over the edge.

As for the motor and electronics. I'm thinking either a newer style ignition (like you mentioned) but from the 80's that would be on an inline 300ci. Or the entire motor could be a 80's 300ci. I don't know if they look that much different. I don't know much about the i6's so one inline 6 looks like another to me, unless they are sitting side by side. You never know what happens to a truck in 40 years.

 

Welcome in, buddy.
There are two small terminals on the solenoid: "s" puts 12 volts to the relay from the ignition switch when you hit start and "i" feeds 12 volts- or what is left of it at the battery terminal while cranking- directly to the coil and distributor, bypassing the dropping resistor. Battery voltage will drop to around 8 or 9 volts during cranking on a normal setup.
Pull the wire to "s" and see if you have 0 volts on the wire when you are not in the start position on the switch. That checks out the switch.
Next, look for 0 volts on the "i" wire. You may be feeding 12 volts back through the "i" wire which will cause the solenoid to pull in as it is internally connected to the "s" terminal.
You may have a stuck solenoid. Disconnect all wires to it and check resistance through it from the battery connection to the starter cable. Open circuit is the right answer, zero ohms is a solenoid short.
An ohmeter check of the starter cable to ground won't tell you anything. The normal resistance through the starter is a small fraction of one ohm which will not show up on a normal multimeter on its lowest scale. You will interpret it as short.
Make sure the solenoid mount is scuffed up for a good ground to the firewall.
I hope this helpsReport back on what you find.

 

John, Thanks. The Solenoid was new however after the episode, the starter motor truly did ground out, shorted the batt when I connected directly to the starter. After that prolonged cranking the windings must have burned through to the case. I took the starter out tonight and disassembled. A lot of corrosion, wear etc. Seems like it was just a matter of time. I guess my question to you is could this have fried the solenoid? I have an open loop between every post and ground bracket except the "S" post to the bracket. A direct short. I wouldn't even test for the "click" because I'd short connecting the batt to the bracket and the "S' post, right? I'm assuming that shouldn't be. Bad out of the box or the grounded starter killed it?

 

Thanks, 7283-F250. I think I've got the starter sit. figured out. You may be on to something with the 240/300 thing. I'll check the engine to see if it's original to the truck. Don't know where the engine code is, though. If it's the original 240 then I guess they just ripped that ignition system out of a post 1974 300cid. and retro fitted.

 

Floppy, continuity between the "S" terminal of the solenoid and ground is normal. You are reading through the solenoid coil which pulls in the main relay to put battery voltage to the starter.
Try this: disconnect the main battery cable from the solenoid and take a jumper wire from the + battery terminal to the "s" on the solenoid. Listen for the click as the relay pulls in. If you hear it, the solenoid is probably okay.
I have seen solenoids fail open and fail stuck closed but I don't remember seeing one shorting the battery to ground. I think you have nailed the problem with starter windings to ground and I think the solenoid will survive the heavy current of the short. That's what they do.
Good luck.

 

Hi all, I've still got problems after installing a new starter and found out what the engine really is in the F250. I've recapped the intial story and added the follow up. Thanks for all your past and future help. You guys are great!



I own the above truck (300 CID straight six) and recently detailed the engine compartment as well as cleaned up the wiring. Before this all was working fine. Regarding the wiring, I took extra care labeling all wires and connections so that when they were rerouted, lengths of damaged wire replaced etc. that the circuits would remain as they were. When it came time to start it up, I turned the ignition switch to run (dash lights on, accessories work) and then held the switch momentarily to start. The starter cranked and kept cranking even after I released the key back to the run position, turned it to off and still cranking. I had to disconnect the battery from the solenoid. Upon attempting to reconnect battery to solenoid, shorting occurred. Something was grounding. I removed the battery's pos. lead and bypassed the solenoid and starter and applied it to all other power circuits and all seemed fine. Tried to connect the battery + directly to the starter and zapp, shorting (multimeter shows no resistance between starter lead and ground, direct short). Upon removing the starter I found a lot of corrosion. This did not answer my "runaway starter" scenario but I ordered a new starter anyway since this one had shorted.
Before connecting the new starter I checked that the solenoid was functioning correctly. I connected the battery + to the incoming voltage stud, left the starter off the switched post and applied current to the "S" post by turning the ignition. The solenoid clicked and disengaged upon turning the ignition switch back to run, then off (I did get 12V at the starter post).
Next I left all power feeding terminals (i.e. volt. reg., ign. ect.) off the incoming stud except the battery and the alternator wire. I did this just to isolate the ignition system and just see if the starting circuit with the new starter worked properly. I connected the starter to its stud and removed the "S" stud wire from the solenoid and applied 12V with a jumper to the battery. The new starter turned fine, removed the jumper to stop. Then I hooked up the starter wire back to the solenoid. I connected all my power feeding terminals (i.e. volt. reg., ign. ect.) back to the batt. side solenoid stud and tried for the first time since my last attempt to start the engine. I turned the ignition and the engine turned. I did this only for about 3 seconds and then to off and run just to see if the solenoid would disengage the starter, it did. Then I cranked it over for 10 seconds. After no start I turned the key to run then off. The starter DID NOT disengage and I had to remove the battery terminal to stop. Upon attempting to reconnect the starter it shorted. I repeated the same thing that happened the first time and burned out another starter! I thought the old starter was perhaps the cause of the problem however the problem still exists somewhere. Meter check confirms direct short to ground on the starter's post.
My question, why did the starter at first crank - then not stop - then short on second attempt to apply power. I can imagine how I am shorting the starter since it does not have an onboard solenoid. Could I be somehow overloading it? And why does it work until I manually disconnect it then short and not work upon reconnecting it? In other words, what is causing it to initially operate while shorted? It seems I messed up somewhere with my wiring, regardless of how careful I was.
NOTE: This '69 model at some point had its original 240 CID point driven engine replaced with a post '74 300 CID with electronic ignition complete with module and all. Apparently done correctly since the engine ran fine.
Thanks for any help you can provide as well as for holding out through the long explaination!
Michael Petruccione