EFI relay electrical question

Many of you will be happy (relieved) to know I finally narrowed down part of my high idle or at least got a clue as to a symptom. The 20A fuse for the EFI had blown. Question now is why. I have developed a hard/too many crank start, especially when warmed up. I realize many things cross paths on the same circuit as the EFI. The FSM specifies starter circuit & fuel pump circuit.

Things I have checked in my amateur electrical travels.
I discovered the fuse because I decided to check the ECM & started with B+ to E7-17 (forgive my misnaming if I do so) EFI to J/B #? & it was way below the 9v minimum. Fuse has been replaced.
I have checked both the starter & EFI relays - good

These are readings I took at the EFI relay connection - They are all taken via the neg battery terminal. Is this (circled - 85) a short to ground?
Other thing is when I checked the starter relay at the ECM, I did go over 6v, however once started it stayed around .36. Not sure if that's of any significance.

 

Are your starter motor connections/terminals clean/tight..?

 

According to any vid I pulled up regarding how to test the starter itself whilst on vehicle, there would be three glaringly obvious studs. Pos, neg & another.
On mine I see one stud with an extended plastic cover over it. I am thinking that's ground? & it's not pretty looking. Then the electrical plug/connection. Pos/power?
I did not see other studs, which if corroded, could cause a problem.

& thank you for responding. I had kinda given up on thinking i might get a response to this thread.

 

The bigass stud, with the big cable and plastic boot/cap is the juice (+) *caution… closing the circuit by say, accidentally touching a screwdriver to the + and the frame, with the battery connected, and POW! electrical excitement! small plastic connector is the solenoid and I thought somewhere on the starter motor housing was an exposed smaller ground wire (-), at least that’s how my ‘99 was. The ground may just be in the bundled solenoid connector on the newer one and, not to insult your intelligence, but…


Generally, as temperature increases conductivity decreases - it becomes harder or less effective to ‘push’ electrical current through a metal conductor (wire).

Basically, a fuse is just a smaller piece of conductor, than the rest of the circuit, that will ‘burn up’, breaking the circuit, if the current is greater than the circuit is designed for. So, very generally…

fuses popping = too much current in the circuit, typically from an unintentional grounding or ‘short’ circuit

appliance won’t run (starter) = not enough current in the circuit getting to the appliance… like from cruddy connectors, which gets worse the higher the temperature.

 

Thank you! Typically my intelligence only gets insulted when I am treated as though I should know everything aka as though I am dumb for not knowing or understanding something

That stated, so if there's not enough current getting to the starter, how does that = too much current in the circuit
The starter & fuel share the same circuit, however the fuse is for the EFI. & I have no parasitic drain, so it's in house....
Also, interesting how the FSM just has you testing the starter from the ECM. Mine did pass these tests, If it were not for me being so darned curious & persistent, I would have just stopped at that. Course now I think my neighbors are getting nervous as I incorporate electrical stuff into my rehab.

 

Ed Zachary…. that is your weirdness.

If the connections were just cruddy, not much of anything would happen or maybe the hard ‘hot’ starts.

If the fuse is blowing, lots of current is going somewhere, just not to the starter…

now, when the starter solenoid slams shut (it’s a big magnetically operated ‘plunger’ switch) there is an instant, just before it makes contact, where the current ‘arcs’ through the sliver of air between the contacts. This repeated arcing scorches and oxidizes the solenoid contacts over time. Just before they fail completely they get a ‘hot spot’… most all of it is fried except one little place. This thing arcs like crazy (lots of current, very tiny surface area). What’s the point: right before the solenoid is close to failing the arcing can: find another path to ground and conceivably carry all kinds of current, popping the fuse back at the front, maybe.

my guess is that some of the current that should get to the starter is 1) being impeded by cruddy connections AND 2) going somewhere else in the fuel/starter circuit.

A two part problem, maybe.

I would:

•clean all the contacts
•check all the branches of the circuit to make sure you’re getting what should be there at the end of each (volts and amps)
•dump a bottle of injector cleaner and a tank of high octane fuel and rev the snot out of it for a whole tank (maybe the fuel system pump(s) are working too hard and drawing ‘extra’ current to overcome clogged injectors)

 

Thank you! This was the impetus I needed to clean it. I had been a little nervous about the nut. All went smooth enough & it's starting better.