Ok I need some help please!!!!!! I have a '79 F-150 that originally came with a 351M, but was replaced with a 351C before I bought it. I had the truck running, and when I went to test drive it the starter stuck and sheared all the gears, and I replaced it and it still stuck. Meanwhile the carburator needed replaced or rebuilt, so I just replaced it. Ok when I went to start it after replacing the carb the starter was still stuck cause it tried to start when I connected the battery cables. I have put four solenoids in it thinking the new ones were bad. I can also disconnect the "S" wire and the "I" wire and it still tries to start when you connect the battery. The next thing I tried was replacing the ignition and the tumbler, no luck again. Ok so then I stipped back all the coating off the whole wiring harness on that side of the truck all the way to the firewall. I did not find any short or stripped wires. I am out of options unless I need to tear the dash apart and look for a short there, but I hope that someone can point me in the right direction without me having to do all that as it would really suck!! I am so frustrated right now I'm bout ready to sell the dang thing for scrap!!!

 

Not sure about your problem 100% but i know if your battery is to small or doesn't have enough power, it wont allow the stater to disengage from the flywheel.

I would unhook the starter and hook up the battery, and get a test light and search why your getting power to the starter wire when you shouldn't be.

You might look under the dash for wiring problems as well, something has to be crossed to be doing what its doing.

 

Are you sure the solenoid is wired correctly???

 

If it tries to start even with the S and I wires disconnected you are getting power to the starter some how and it is not coming from under your dash or wire harness. I would most like say the solenoid contacts are welded together. Like previously stated disconnect starter wire from solenoid and see if it still does it. If that works get a new solenoid make sure you have a good ground on solenoid and see if it is chattering when starting causing it to chew up the contacts so fast. If it is then your problem woudl be on power coming to your coil on the solenoid.

 

Yes I can disconnect the starter cable from the solenoid and it stops the starter, and I'm sure its because that is the only wire attatched to the starter. it should be getting a good ground it has not been painted or anything, but I did take it off the fender and sand the area where the screws attatch. It has a brand new battery with 700 cold cranking amps, wasn't sure how much to get cause it didn't have one to start with, but since our diesels use 800 cca I figured that 700 was plenty especially since most are less that that anyway, and it has a full charge I checked it with my battery charger and it is also putting out 12v according to the charger and the volt meter. The solenoid is wired the exact same way as it was when I got the truck and it didn't do this initially when I bought it, but I have went through 4 solenoids, but I have read on other forums where you can buy a better quality one, which is something that I need to look into. But heres another thing, the one that was on there when I purchased it looked one way and then the next ones I got were different, and the one that is on there now looks just like the original. I intially replaced it because I replaced the started and you are supposed to change it when you replace the starter. I don't think I have the original one now anyway, so I can't go back to it. Thanks for all the replys and it is much appreciated, but like I said before I have tried seems like everything, think I am gonna try another solenoid though, because it does not engage with the starter cable removed from the solenoid.

 

why have you gone through 4 solenoids? Were they bad or are you just changing them out because you think it might fix the problem? Have you tried running jumper cables to bypass the solenoid, or better yet, go directly to the starter? Is your truck a manual or an auto? Some of the manual swaps people ghetto up the flywheel with spacers and etc, it could be jamming the starter gears and not allowing it to turn. You could try just unbolting your starter the way it is and seeing if it engages and spins when its unbolted. If it does it could be your flywheel set up. If not then its dead. Its not totally unheard of for rebuilt starters to be dead in the box or to die after one or two starts. Sometimes you just get a bad one.

Normally when you are troubleshooting a system you start at one end and work your way to the other. You can't just start replacing components without knowing whats wrong or you may end up swapping something that works for something that doesn't, and then you have 2 bad components in the system.

Also, you can use a multimeter to test a battery for bolts, but to know what kinda shape its in you have to load test it, which most of us don't have the carbon pile or electronic tester to do. If its new it should be good, but if you have a parts store nearby it never hurts to have it test to know for sure.

 

Ok the first solenoid was the one in the truck, I replaced it as you are supposed to when you replace the starter. The next two just make a clicking noise and wouldn't engage the starter, the one that is there now won't disengage the starter. I am not replacing stuff just to do so cause that just costs money, that I would rather not spend if I don't have to. I am just trying to get the darn thing running and these have all been suggestions from people on my problem that seemed to make sense. I have not tried running a jumper cable to the starter from the battery, but I can try that too.

 

I would pull the starter and check the gear. While it's out hit it with some jumper cables and see if its engaging and disengaging like it should.

 

Never heard the advice of replacing the starter regulator, when you replace the starter?

Now after you replaced 2 and all they did was make a clicking noise, that says to be bad connections/ground or low battery. 14+ on the volt meter befor start?

Then with a jump start you welded the starter solenoid and now its stuck your starter on. Have toy tapped on the starter solenoid (round elec component on the pass inner fenderwell)?

I would 1. take the starter to auto zone ect...and get it tested and that will cover the solenoid on the starter itself.
2. get a quality starter solenoid (fenderwell one)
3. Insp all power cables, ck any fuses, all you ground cables.
4. Make sure all the wiring is correct IAW a diagram, and then chk it again.

I always make then bench test any NEW starter and NEW alternator before I WALK OUT THE STORE. Has saved me a trip or two, and a lot less case of the PO return customer.

 

Here you go...even though it a 67-72 wiring schematics can grt you in the right direction.

Do not want to confuse the "starter relay" with the "starter solenoid".

I call the component on the inner fenderwell the starter solenoid....might be wrong but its a habit I can't break.

I believe the starter solenoid is on the starter itself? I hope I did not to confuse you. And good luck getting it fixed.

 

You don't have both the positive battery cable and the cable going to the starter on the same selonid post by any chance?

 

No the cables are not on the same side. Now the starter is not stuck but now I am having a different problem. The starter wont engage with the key the only way to engage it is to put a srewdriver between the terminal where the battery connects and the s terminal. I am tired of electrical problems!!!

 

If (other than using a screwdriver) the starter then works properly, you could get a good 50 or 60 amp push button like the old days. You won't need the little wire at the solenoid, just hook the 2 wires of the button directly (one on each side of the big terminals of the solenoid). The truck will crank whether the key is on or off, but can't start without the key on. You should use good and heavy enough wire from the push button to the solenoid and good connectors at the solenoid. You could put an in-line breaker between the button and the solenoid for extra safety. The button can mounted right in the dash somewhere.--Hope this helps.

 

Quoted from hasteranger:
Have you tried running jumper cables to bypass the solenoid, or better yet, go directly to the starter? Is your truck a manual or an auto? Some of the manual swaps people ghetto up the flywheel with spacers and etc, it could be jamming the starter gears and not allowing it to turn. You could try just unbolting your starter the way it is and seeing if it engages and spins when its unbolted. If it does it could be your flywheel set up.


This from Vintage Mustang Forum:

Question: Will a 351M 400 flywheel fit properly on a 351C. I'm setting the car up for a 164 tooth, 11 inch clutch. The car is a 70 mustang with a soon to be toploader and a 351C
Answer: no it will not. way too large. the 351M/400 fly is the same diameter as the FE/385 series fly's. what you need is a 302/351W/351C 11" clutch flywheel. I have several if you are in dire need. or you can junkyard for one. look in mid 70's ford trucks with V8 small block. make sure it hasn't been turned to excess and doesn't have heat cracks.

-Just an idea like hasteranger mentioned. With my earlier post to you 4X4 Family, I was only looking at the electrical aspect and not the mechanical.
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you could do that, but that function is already built into the ignition switch. I know electrical problems are frustrating and can be difficult to diagnose and repair, but I don't see the point in running duplicate wiring. The correct fix is to find the reason the key isn't actuating the solenoid, and its gonna take using a multimeter or at least a test light to find out what is going on. At this point in time it sounds like it could be the solenoid, but you'd have to know if the switch is even actuating the solenoid to make sure there isn't a wiring problem somewhere between the switch and the solenoid.