Ford relay or starter issues?...

[Caver Dave]

'91 5.0HO w/ factory everything (Mustang if it matters?)... pressure washed the engine on Sunday to remove 20 years of gunk. She fired right back up, so I backed it into the garage & shut it down (didn't want to warm the garage back up to 120* ) An hour later, went to fire it up and got nothing but clicking relay (inner fender). I'd had the interior light on for that hour, thought I'd drained the battery a bit, so put in the charger overnight. Monday AM had NO power to anything (no lights, fuelpump, etc)...

Confirmed 12V at ALL points using battery -, body, & block grounds (no DC amp meter):
- Battery = 12.6VDC
- Hot lug of relay = 12.6VDC
- "S" terminal & starter lug = 12.3VDC while in the crank position or jumping to "S"
- ALL connections from battery to relay are clean & tight

Now, when key is in the "start" position, I get a single light click on the relay. continue to get the 12.3VDC at "S" & starter lug. When key goes back to "run" position, no voltage on "S", BUT still read about 6-7VDC on the starter lug! It will stay this way (latched, low voltage to starter cable, but nothing smokes or gets hot) until I remove power by yanking one of the battery cables. At that point, the relay will "open" and when power is re-applied, will have poer to lights & FP spins up in "run". "Start" gets the single click and we're back to the beginning...

Also, if I jump the relay (huge C-wrench) across the hot/starter lugs, I get a very light spark, but no starter action...

While I probably should replace both relay & "BIG" starter (IIRC, they went to a "mini-starter" in '92-'93?) now after 160K miles, I don't want to throw parts at it...

Between the relay appearing to function fine (except for the low voltage "latch") and jumping the relay giving me nada, I believe it's likely either the large factory starter wire, connection to the starter, or the starter? Haven't tried frapping the starter w/ BFH yet...

Hoping to get some consensus or additional troubleshooting info!

 

[upnover]

Sounds like you help shorten the life with the water. I would go with a starter relay, and a cable to the starter first(least two expensive things. You can try and run jumper cables to the starter and to your battery to see if the starter will in fact turn the engine.

 

[Caver Dave]

Sounds like you help shorten the life with the water

Agreed... in hindsight, I probably should've left it running for 10-20 minutes to get everything hot under the hood/block and let it dissipate the moisture. But I was finishing up installing some "Peel & Seal" (self-adhesive roof flashing... same type of stuff Rich used on his CTD) to the entire floor and didn't want to wait 3 hours for it cool back down

I would go with a starter relay, and a cable to the starter first(least two expensive things.

Agreed, but still trying to keep it cheap!

You can try and run jumper cables to the starter and to your battery to see if the starter will in fact turn the engine.

I'm 95% with the P&S install, so will get back to this tonight/tomorrow afternoon... and that's one trick I'd forgot about.
One of my co-workers seems to think it's likely the starter itself based on years of replacing dead the large case starters. I believe this would be the perfect time to upgrade to the newer mini-starter anyways (if the budget holds out that long! )

 

[shawn]

It's got a standard Ford relay up by the battery somewhere? Just put the key in "run" and short the solenoid with a screwdriver.

Make sure the transmission is in neutral first.

 

[Caver Dave]

It's got a standard Ford relay up by the battery somewhere? Just put the key in "run" and short the solenoid with a screwdriver

Correct, and already covered... nothing

Also, if I jump the relay (huge C-wrench) across the hot/starter lugs, I get a very light spark, but no starter action...

Make sure the transmission is in neutral first.

Funny! A bud in HS spent a year rebuilding a nice '70 Mustang. After spending the day cleaning it in the carport, couldn't get it to turn over. He quickly jumped the relay... it fired right up (high idle) and because it was in REVERSE (the reason it wouldn't crank in the first place)... proceeded backwards out of the carport! When the open driver door contacted the brick wall, it folded back against the fender... seconds before the ass end hit the back of his school-bus parked in the yard, destroying the bumper/taillights/trim!

That was 30+ years ago and I *ALWAYS* confirm neutral/park before cranking a vehicle!

 

[shawn]

If you're shorting the solenoid and getting zero starter action, you've got a bad battery cable or a bad starter.

Chip's jumper cable idea should narrow down the possibilities there.

 

[Caver Dave]

If you're shorting the solenoid and getting zero starter action, you've got a bad battery cable or a bad starter.

Chip's jumper cable idea should narrow down the possibilities there.

Shawn, elaborate on the "bad battery cable"...

That would manifest in the form of no starter/tiny spark due to reduced amperage, correct?

 

[upnover]

Well not actually the Battery cable, but, the Starter cable. The cable could be bad because of corrosion and or oxidation. The strands of the cable will get coated and power just can't get Through it. The jumper cable from the battery to the starter will alleviate the starter being bad, that is IF the battery is good and charged.

 

[Caver Dave]

Well, did get a chance to look at it tonight... Started with cleaning, tightening, & confirming the battery cables & clamps (battery & clamps 4 months old), then moved to the relay. After finishing the treatment on the 5-6 wires terminated there, checked voltage points again and only had 5VDC!

Turned on the headlights and nothing... So started "agressively" wiggling the battery cables, when I heard the negative cable arcing inside the clamp (4 month old "pre-terminated")... WTF over?

Swapped it for an AZ "DIY" clamp & bit of recycled cable from the Moss and the headlights came on... Jumped in and she fired right up!

The bad cable has no physical signs of failure (the lead is still shiny!) and while still connected inside the clamp (won't pull free or spin) that was definitely the problem!

Thanks for assistance gentlemen!

 

[shawn]

A bad battery cable will drive you fawking crazy. The problem is that there's still an internal connection, so the cable will usually ohm out okay, but it builds up resistance fast if you try to put any real amperage through it. Kinda like trying to spin the starter off a piece of 24ga wire. Power gets through, but not nearly enough.