I had the same thought but figured since I am having this problem I shouldn't start modifying things. Already have correct one ordered so I will just do that.

 

Of these starter relays, have they all failed the same way? Lots of comments here and in other threads about the suspect quality of some replacement parts, especially electrical items. However, if you inadvertently kept purchasing junk, I'd expect to see at least a few of them fail by not engaging the starter, as opposed to sticking in the on position like you've been experiencing.

How long does a new starter relay last before sticking? Has that timeframe been fairly consistent?

Just trying to get a handle on what may behind all this.

Can you duplicate the problem consistently, or is it hit or miss? Next time it acts up, try disconnecting the small terminal that energizes the relay. It just plugs on, doesn't it? If disconnecting that terminal shuts off the relay, then you'd know it was somehow getting power when it shouldn't have.

 

This would not be a good idea. That second small terminal is part of the circuit to the electric fuel pump. This portion is only powered during Start, and provides an alternate source of power to the fuel pump until the oil pressure switch closes and completes the normal path of power.

If you moved that wire over to direct battery power at the feeder cable, the electric pump would always run, even with the key off, with no oil pressure, or with the inertia switch tripped.

If you moved that wire over to the start terminal, once oil pressure rose after starting, that terminal would get back fed from the pump circuit. This would reengage the starter relay and run the starter continuously.

Neither option sounds very optimistic...

 

There's a diode in the pump wiring, so it cannot back feed.
Maybe you should look at the EVTM....


Eta, there's no way the fuel pump wiring could "engage" the starter relay from the *output* stud, nor would a 20Ga. fusible link EVER be able to drive a starter motor....
Really a non-issue.

 

Maybe I didn't understand what you were asking in post #30. I thought you were asking about relocating fusible link T, as seen (poorly drawn) on page 26:

Start & Ignition - ???Gary's Garagemahal

Follow that out to page 102 (single tank) or 105 (dual tank). Once the engine is running, with normal oil pressure and the inertia switch not tripped, hot battery power from fusible link S is back fed to T through a resistor wire. Not seeing any diode in that part of the circuit, but not really an issue because the starter relay terminal connected to link T is isolated at all times except in Start.

I do fear we are getting sidetracked here. I must not have understood your intent when asking about relocating wires to work with the other style of starter relay that has one less terminal. While troubleshooting we'd want to stay with the original style relay and not move anything around from the stock configuration.

Call me confused...

 

Kr, I owe you an apology.
The diagram on p 102 does *not* show any diode.
Obviously ** I ** should be taking advantage of Gary's excellent resource...


I have had trouble accessing this site from my phone this morning.

 

No problem, it just had me scratching my head, that's all.


Maybe you can do me one small favor. Could you hire a skywriter to fly over every FTE member's house with a simple banner, something to the effect that I was right? As a married man, I don't get to experience that sensation too often.


Thanks.

 

I would rep you for that if I could, Karl, but I need to spread the love around some more.

 

Well, l can't rep from my phone either.

Must have in mind a later 460 schematic, from after Ford went to the 3 terminal relay.
(maybe something Subford posted about an F53)

 

Tried to rep ya as well Karl ... But, As usual got the You must spread some Reputation around before giving it to kr98664 again.

-Enjoy
fh : )_~

 

OK...did the voltage drop test and everything is good. The only thing I did not know for sure is when I had the positive probe on the positive battery post and the negative on the starter side of the solenoid it was reading battery voltage with key in off position.

I also figured out the truck will not crank at all if the "I" wire is not hooked up(which it does run the fuel pump). Even if I jump the solenoid with a screwdriver it will not turn over unless that wire is hooked up. I took a test light to see if the "S" wire was getting power when switch turned and it does every time, but if the "I" wire is not hooked up the truck will not turn over. With friend turning key I could touch "I" wire to solenoid and it would start cranking, if I removed it it would quit cranking. I was just blown away that it would not crank when jumping the solenoid with a screwdriver unless that wire is hooked up.

Also when starter stuck one time I removed both the "S" and "I" wires and it just kept turning over, slightly tap solenoid with pliers and it quits.

I cut apart a solenoid that had stuck 10+ times to see what contact areas looked like and they looked brand new, no burn spots what so ever. I don't believe the solenoid is sticking by burning together but somehow electricity is allowed to flow and keep it in contact.

I am beyond blown away here, especially with the silly thing not turning over by jumping solenoid with screwdriver and it still wont turn over unless the "I" wire is hooked up.

 

Ok if I under stand you right the wire that goes to the S stud has hot with the key to ON or is that to START? It should only be hot with key to START.
S stud on solenoid should only get power if you want the motor to crank.

When jumping the solenoid to try and get the motor to crank did you run power from batt + to the S stud or where the + batt cable is bolted to to the S stud.


Wire on I stud would be hot with key to ON. The I stud should only be hot when cranking the motor. This I stud sends a full 12 volts to the IGN system thru the wire that hot with key on.


If I was reading your post right it sounds like you may have the S & I wires mixed up. Could that be right?


If you have no I wire or stud and the S wire is hot all the time then it is getting power from some place? Bad IGN switch or out of adjustment?
Just my .02
Dave ----

 

I was wondering the same thing, but haven't done the complete mental gymnastics to see how that would play out.

For my understanding, can you please confirm if page 26 here is correct for your truck. I want to make sure I understand the S and I labels correctly:

Start & Ignition - ???Gary's Garagemahal

If I'm extrapolating correctly:

1) S is the terminal that should get 12v via the ignition switch only with the key in the Start position. It's connected to wire 32, which is colored R/LB (red w/ light blue stripe). S is illustrated at the upper right corner of the starter relay in the EVTM.

2) I is the terminal that connects 12v to the fuel pump circuit when the starter relay is closed. It's connected to fuse link T, which is 20ga blue. Fuse link T is connected to wire 787 (pink w/ black stripe). The EVTM is poorly drawn here, but the fuse link should be connected to the lower middle terminal in the diagram (that's how it is in my '84 EVTM).

3) The only other terminals on the starter relay are the 2 big lugs for the big cables.

Is that a correct description of the starter relay and how the wires are connected?

 

Yep, that's normal, so don't be alarmed.

Thanks for taking the time to run the voltage drop test, even though we didn't find a "smoking gun". Even so, the results help rule out a lot of possibilities.

 

What were the voltage drop figures for the positive side?