dirtyrobinson

I'm really lost at what could be causing such a drop in voltage when cranking. My 85 coupe struggles to start at operating temps unless I let it sit for an hour or longer. The starter is new, the battery (1 year old) was tested, the alternator (1 year old) was tested and all are fully functioning. The battery terminals read 12.2-12.3v when the car is off and when the key is turned on. The dash reads 11.9v. When I go to start the car it just keeps cranking and the voltage drops as low as 7 volts. When it starts, the voltage is at 13.9-14.2v, doesn't ever drop below or go above those numbers. The check engine light doesn't come on either.

If the starter, alternator, and battery are all ok... what else could be the problem?!

I cleaned all of the connections as well to ensure each part had a clean contact point. Nothing has helped fix the problem.

illenema

Symptoms of a bad starter when Hot

dsandmire

Could still be a bad battery or bad connections at the battery or at the starter could do it too. Full 12v bat ar rest is 12.6or7v, 12.1 or 2v is half full; below 12.0v is less than half,,,,,,

oldalaskaman

Its a chevy design flaw, easily cured by a ford remote starter solonoid which was actually installed by GM for a few years and has a GM part number, hold on I'll find it.
Here ya go,
AC Delco #U939 ,Jegs 'with their own part number sells it in a kit with directions and installation parts.

HlhnEast

My old suburban was so bad at heat soak at the solenoid I had to keep a screwdriver handy to bump the contacts. I doubt seriously you can do this with your vette. I figured the headers had a lot to do with how much heat the starter took. Before I figured it out trying to get enough speed up to pop the clutch on a 5800# vehicle was NOT easy. Make sure all the electrical contacts at the battery and the starter are free of corrosion, oil etc and are tight as well.

dirtyrobinson

I saw a similar post and someone mentioned the heat cover and while that makes complete sense, would that cause the drop in voltage too? I was almost thinking the relay but the other thread has me convinced to buy a heat cover for it regardless!

dirtyrobinson

Also, for reference, does anyone have a PDF of the schematics for the 1985 charging system? The one in the Chilton manual seems a little incomplete. It only shows 2 wires connected to the starter (battery and ignition switch), but there are 2 more wires coming from the alternator that has fusible links on them.

oldalaskaman

by the time your starter gets to the point its at now, you should just replace or rebuild, the fixes , including mine only keep it from getting to that point. time to buy an FSM

dirtyrobinson

Apologies to those helping me (and anyone with a similar problem), been a long week so I haven't had any time to work on my car. I did some testing today and I think I can check off a few things.

After bringing the car up to operating temperature I turned it off for 30 seconds and it fired right up. I waited a minute and it fired right up, I then waited 15 minutes and it struggled a little but it did fire up after 5-7s. After waiting another 30 minutes it didn't wanna fire up. It would crank endlessly without losing cranking "power" (steady cranking sound) so I tried something I read from a similar post a week ago. With the key off, I pushed the pedal to the floor for 10-15s to let any fumes escape. I turned the key and wouldn't you know, it fired right up (exhaust smelled pretty rich though).

I would have to look my in history but the thread I was reading, someone said this is a symptom of a leaky injector. I'm unsure how to test injectors to see if this is truly the problem or not.

Since the starter was replaced a couple days before I started this thread, I ordered a heat shield to protect it as well. I checked all wiring, anything I didn't like, I rewired. Volts are steady at all connections. So, I think I found which direction I should go in. I'm gonna start reading up on testing injectors and hopefully I can pinpoint which one is giving me problems!