Just had to jump-start the car for lunch. My tach reads a constant 1800 RPM no matter what, battery drain somewhere, disconnecting the tach lead from the HEI changes nothing.

Any guesses? I haven't been working on the car for a couple weeks...

Tach won't have much to do with anything. Didn't you have charging problems 3-4++ weeks ago. Think we were talking about chargers or boosters or something? What happened then? Could be wrong, maybe someone else. I don't remember everything.

I replaced the alternator, then the voltage regulator. All has been just fine since then. I'm wondering if it's maybe a coincidence with the tach and something else? My USA-2 stereo still cust out (we had the discussion here about bad "constant power" wiring, but I've checked that. What I haven't checked is the "box" on the power feeds to the USA-2 (has a fuse and some other electronic stuff in it, don't know exactly what it's supposed to do). Maybe that's flaky.

For now, I'll just disconnect the battery when I park it...

If my memory hangs on there is only a small line that ties to the constant memory on the USA-1. There's a line filter for that radio in the box. That line shouldn't run down the battery.
See if the alternator circuit is charging after you jump it. I'm sure you already checked the battery cables at the battery and block. Old battery? Battery take a charge with a battery charger? My 84 month Exide battery dumped last Saturday in my truck after 36 months. I barely drive that truck so it sits and eats batteries.
(Costs me about $25.00 because of the prorated warranty *84months-36months* and the warranty starts again from day one. My cheapest option on the vehicle.)

Weekend project. Battery is old, and doesn't have enough cranking amps to start the car when it's hot, so I've retarded the timing to cover this. Still bogs once in a while. I'm sure I could use a new one. Without having put tools to it, the amp meter reads slightly + for a while after starting, battery charges enough so that the thing will start next time.

I'm going to disconnect the USA-2 for the time being, while I look at other stuff. All my connections are good, so I'm suspecting the box on the power line as having a problem. If it's 12V to the unit, maybe I'll bypass the box and see if the problem goes away. It may only be a noise filter, but I don't know why there'd be a fuse in it.

As for tach, I guess I'll have to pull off the dash cover and see what I can see. Hopefully something obvious...

Originally posted by John_Muha:
Yo-ho Yo-ho a pirate's life for me.
Had to open up one of the kid's Christmas presents early. That's one fun movie!

Just my opinion but I've had some luck with the 875 CCA Exide batteries from Kragen.

How do I test for a drain on the battery? I have a multi-meter, and can follow instructions pretty well. If I hook up one side to the battery +, and the other to the + cable (while it's disconnected) I should see something, right? What setting on the meter do I select, and what do I look for?

Teach me to fish, John!

I'd recommend doing it with the negative cable. Just a different way to do it. Disconnect the negative cable from the battery and put a light bulb and socket between the battery and negative cable. The light should not come on. If it does:
Disconnect anything such as that memory line plugged into the BAT terminal.
Have a clock? Unplug that?
Still comes on, separate the positive lines on the horn relay. It should go out.
Connect those lines back one at a time and see if it is the alternator or it's inside the car.
If it's inside the car, pull fuses one at a time until you find the drain.
May still not be a drain problem. It could be charging or a weaken battery but you know how to check for those.
Later, Miller Time

arhggg matey if ya be asking me its the voltage regulator.When we installed a volt meter we saw the tale arhgg.Lots of discharge idling around town especially with the lights on.Go SI its cheap and easy,haven't had a problem since we changed over.May the electrons always be to your back

Originally posted by JohnnieV:
May the electrons always be to your back Aye, but then you'll be facin' an onslaught of holes comin' at ye head-on!

Ok, it looks like I'm in for a new battery. Can't find any steady drain, no light using John's method. I've had the car since December 2000, so the battery is at least three years old...

Put in a new battery (Optima red top), no more dead battery problems. Of course the old one tested fine, but the guy couldn't explain why it would go dead after sitting with the door open for ten minutes...

I still have the tach problem, though. Guess I'll pull the dash cover off and see what I can find in there. I need to clean that out anyways...

Thanks all...

Did you check the charging circuit again?

Yes. Well, I didn't. I stood there while the Sears tech hooked his equipment up to my car (no, THAT's NOT what I mean ;) ) and did his tests. Charging is good, which is a good thing since I have a new 105 amp alternator and new regulator. Everything else appears to be working just fine, and it's quite possible the tach problem is a total coincidence...

Sounds good. As I mentioned in my first post I don't see how the tach failure is related.