SliceIROCZ

Ok guys and gals I’m at a loss with this one.

My car will not start. As in, it doesn’t even try to turn the engine. No noise, no spin. I need this fixed ASAP since it’s my daily driver. Details to follow

1990 5.0 TBI automatic

back story: car had been getting harder to start gradually. First start of the day usually took a few seconds but follow up starts we’re quick. The exception being that occasionally I would turn the key and get nothing. Try once or twice more and it would work fine. Recently went to start car and nothing happened when I turned the key to start. Tried several times over 10 minutes. Twice it started to turn the engine very slow but stopped. Finally it turned long enough that it fired and I got it home. Drove normally all the way home. Parked it and now it will not start.

What i have done: battery tested good. Starter tested good. Verified the ignition side of the VATS is good (showing correct resistance from ignition). I have 12.7V on the starter’s main post. When I turn the key I get the same voltage from the purple wire. Engine turns by hand with minimal effort.

I have run through so many posts here I can’t keep them all straight. What have I missed, what can I test, I’ll try anything at this point. Please help

Slice

sofakingdom

iTrader: (1)

Sounds pretty obviously like a bad starter.

What happened when you replaced it? (not "test", whatever that is)

A somewhat more definitive "test" - more reliable BY FAR than what they do at parts counters - is to have your assistant hold the key down while you whap the starter itself with a tire iron or BFH or some such. If it starts by doing that, you DEFINITELY need another one.

SliceIROCZ

Starter was run on the bench. Ran like a bat out of hell with no issue.

mikeceli

iTrader: (2)

Was it under LOAD?

SliceIROCZ

I had to actually ask since I couldn’t see the machine that did the test, but no it’s not a test under load. I guess it’s possible then that it isn’t working once it hits resistance but it doesn’t seem to even engage. Nothing appears to happen when I turn the key.

GeneralDisorder

iTrader: (1)

Check voltage on the solenoid wire with an assistant holding it in the crank position. I think you will find you don't have sufficiently good connection to actually engage the solenoid. It shouldn't drop more than 0.5v

GD

antares57

iTrader: (8)

Sounds like you have resistance in the ignition to starter circuit. My '88 did the same thing. I hooked up a push button start for those occasions that it won't start.

mikeceli

iTrader: (2)

A NO LOAD starter test, is NO TEST.

With nothing happening when you turn the key (Crank) someone needs to test the system, battery, ignition switch, wiring, starter, etc.

With engine off, headlights on, have a helper crank the engine over, if the headlights dim appreciably, the battery is bad, assuming the related wires and connections are good.

SliceIROCZ

The voltage on the solenoid wire tested at 12.58V, within .2V of the wire from the battery when the the key was held in the start position. I already tested the battery outside the car, but the headlights don’t dim significantly when attempting to start. Weather precluded any more troubleshooting today, no garage at the moment, so I will try a new starter tomorrow.

I’ve also chased the voltage from ignition all the way to starter solenoid with no break or drop in voltage

mikeceli

iTrader: (2)

So the "Exciter" terminal on the solenoid is getting full voltage, but the starter doesn't crank. Question is, is the B+ (heavy wire from the battery) supplying proper voltage and amperage? Can you use a battery jumper set (one side) to go from the battery + terminal to the heavy terminal on the starter and retest? If the starter fails to crank w/ full volts and amp supply, either the engine is seized (which I believe you ruled out) or the starter is BAD, or not grounded properly. It grounds bolted to the engine.

PS ARE ALL ENGINE GROUND STRAPS IN PLACE AND CONNECTIONS CLEAN AND TIGHT? Starter body grounds to engine, engine must have a good ground, to body/chassis, going back to battery neg terminal.

QwkTrip

iTrader: (22)

Sounds like you're doing a good job troubleshooting.

If the solenoid pull-in coil is burned open then the solenoid won't throw. But if that were the case then the starter likely wouldn't operate during no load test either.

Could be a poor ground path back to battery. Clean up the metal at mating surfaces at the starter mounting pad and the flywheel housing. The ground strap from engine to frame should be of same (or similar) size as the B+ cable that goes to the starter (whether or not GM did it that way). Make sure the flats of the wire terminal are clean and free of paint, as well as the mating surfaces at the engine block and frame. Same with the cable to battery negative post, and the battery post itself.

Don't rely on bolt & screw threads to carry current. Threads rust over time. You want bare metal to metal contact between ring terminal and the engine and frame. GM relied heavily on screw threads and that's a big no-no in electrical systems design. The bolt/screw clamps the ring terminal in place, and the flats of the ring terminal carry the current.

You'd be surprised how little oxidation it takes at a connection to keep a starter from working. A ring terminal has a large surface area but in reality most the current is passing through a single point of contact. A little bit of damage or contamination at that point can sometimes stop the whole show.

GeneralDisorder

iTrader: (1)

You have to check the solenoid. Are you bench testing through the solenoid or directly to the motor?

And when you check the voltage to the solenoid, are you doing so with the wire attached to the solenoid? You need the load..... instead of using a volt meter try using an incandescent test light to put some amperage load on the circuit. Voltage is only half the equation - the wiring needs the ability to carry amps also.

If the starter works on the bench and you have 12v everywhere it needs to be (and ground).... if these statements are taken as fact then amperage must be insufficient to do the work required. It's that simple.

GD

QwkTrip

iTrader: (22)

There is good voltage at both the starter B+ and switch terminals, and the OP says there is no clicking noises at all. That indicates the solenoid is not throwing, and motor contacts are not closing. That helps narrow the field down to either,

* Solenoid pull-in coil is burned. This is a very common failure mode when the solenoid won't actuate and back to back start attempts are made during troubleshooting. It's a secondary failure mode that finishes off the starter for good.

* Solenoid plunger is seized to the plunger core. Caused by moisture & corrosion inside the solenoid over time.

* Poor ground path to battery. It's an old car and crap happens.

Reasonable next step is check ground path. And if that doesn't work then replace the starter. I think he's done a pretty good job checking the high side of the circuits. Load testing the motor doesn't matter if the solenoid won't throw in the first place.

sofakingdom

iTrader: (1)

You've already done all the troubleshooting there is to do. It has demonstrated that your starter is defective.

The "parts counter test" is ALL BUT WORTHLESS. The only thing it will find is a COMPLETELY DEAD one. Yours isn't completely dead though; it's only dead SOMETIMES and under SOME CONDITIONS (which aren't duplicated during that test). "Not completely dead all the time" is NOT the same thing as "good".

Replace the starter. You're wasting your time posting any more about it on the Internet.

GeneralDisorder

iTrader: (1)

It probably is a bad starter (or at least a bad solenoid - which is effectively the same thing) - but how did you bench test it? Though the motor or through the solenoid?

Obviously it is always a good idea to check your battery cables, terminals (side post bolts also), and the solenoid power wire. And it's best to check that the solenoid power wire can deliver usable amperage.

I don't play swaptronics. Besides the fact that it's stupid when you can just do the actual tests to prove exactly what the failure is, I can't do that because I own a shop and I have to be 110% certain of what the issue is and what I'm replacing.

GD

Bow_Tied

iTrader: (1)

When I have found these issues, it's always been the solenoid or wire/connection (I once found a PO had 4 splice connections in the wire running to the solenoid!). The solenoid is 2x more suspect if running headers.

Doing a good job troubleshooting, good luck.

sofakingdom

iTrader: (1)

Did you try the tire-tool/BFH test? It's VASTLY more useful and reliable than the "parts store counter" looks-enough-like-a-test-to-fool-the-näive.

SliceIROCZ

Not having garage at the moment has hampered my troubleshooting as the weather hasn’t been great. Thanks for all the responses. I’m going to check the grounds and clean up the cables (B+ cable has rust on the eyelet) and if that doesn’t work I guess I’ll replace the starter.

And no sofakingdom your BFH technique doesn’t help.

SliceIROCZ

First off thanks for everyone that came to my aid with suggestions. I have finally fixed the problem and have the car running once again! In the end, it was a solenoid that appears to have the B+ bolt breaking loose (solder must have failed internally). We only figured this out after I decided to just buy a new starter out of frustration and the parts guy insisted on testing it. That’s when we noticed the bolt had some play in it. (Could have been the BFH test)

some lessons learned:
The Autozone starter tester does test it under load, wired through the solenoid, simulating it is on the car. (I can only speak to their tester since I only used them)

A solenoid failing, but not totally dead, will decide to work at the most inopportune time. Mine appears to have had its last hoorah on the tester, which is why it passed. When I took it back today we tested it and it didn’t work at all.

It pays to do your due diligence when troubleshooting. I learned several things about my individual car, like half-assed wiring from pervious owner, I would not have seen otherwise. I also know for certain that the new starter had everything it needed to work. It is also better to troubleshoot with testing rather than your credit card.

Lastly, when you have eliminated the impossible, and tested all the possibilities, follow the clues to the most likely failure and start there.

Thanks again to to everyone for your time and help. I know this won’t be the last time I enlist your help but hopefully next time I can help someone else.

Slice