"Fun" with tachometer and pressure guage
 

Well, I'm back. Today, the tachometer just started jumping all over the place. The car would jerk and sputter during the jumping, but there is no way the RPMs were actually going that high. That being said, when in neutral, it was still doing it at a light, and eventually died. It started right back up and I was able to get it home.

is the video I shot while it was happening. Sorry it is not the best, but (for obvious reasons) my eyes were on the road.

Odd thing is when I started it up 15 minutes later, it ran perfectly all the way back home.

Also, on a random note, my fuel pressure gauge stopped working recently.

This is the only thread I could find on a similar issue. The coil, distributor cap, and spark plug wires are all new within the last year, so I'm not convinced it is the same thing as that thread. Any other suggestions? bad vacuum lines? Something more nefarious?:102:

Do you have a fuel pressure gauge? Or do you mean fuel level?

Most all fuel pressure gauges are mechanical.

As for your jumpy RPM's, I'd start with checking the coil & ignitor wires to make sure they are secure & free of corrosion (the tach gets its signal from the - coil connection (blue wire)).

Also what does your voltmeter say when the engine is running? A dying alternator can cause all kinds of electrical weirdness.

oops, I meant my oil pressure gauge. Fuel tank gauge works perfectly since I swapped gas tanks last year.

just checked and the cap still looks new, and the wires were firm and had no corrosion. The rotor does have a bit of wear, but looks otherwise fine.

Voltmeter usually reads between the 14 when idling and about 16 when running. When I start the car in the morning, though, it drops down to 10, and it always feels like the battery BARELY has the juice to get the car started. I had the alternator load tested last year, but maybe I'll have that done again.

I'm talking about the coil... not distributor. :D

Oil pressure sensor probably needs to be replaced (common prob).

You should take your car to AutoZone & have them do an on car alternator / battery test.

I should have been more specific: The wires from the coil was tight with no noticeable corrosion. The blue wire looked fine as well. I had the battery tested by auto zone just a couple of weeks ago because of the weak starting problem. I'll get the alternator tested asap.

I can't find an oil pressure sensor. Closest is an oil pressure switch. same thing?

The stock volt meter sounds like it's out to lunch as well. I'd check the voltage with a good meter. Make sure your battery cables are good too.

Took the car to autozone to have the battery and alternator tested. Long story short, it had the wrong type of batter in there, so I bought a new battery and new cables. The ground goes to the body before going to starter motor.

But, after putting in the new battery, they did an alternator test, and said the alternator is also bad. What are the odds of both going out at the same time? I think I'll swing by an O'Reilly's on the way home from work today and get the alternator re-tested.

"Bad" is such a generic term.

Did they tell you how many amps & volts the alternator was putting out?

You also have a spare higher amp alternator in your turbo car. :D

I was already 4 hours late to work, so I didn't press much on what they meant by "bad." Basically he said it isn't charging the battery.

That was actually going to be my next question, was if I can just yank the alternator from the turbo, or if I need spend the $45 for a re-manufactured one. I've seem to remember you recommending an upgrade to a GM 1-wire alternator for upwards of 150 amps. If I'm swapping the engine and everything already, it seems like it might be a good time to get the upgraded alternator. Is this the type of alternator you're talking about?

^^^ Yup, that one. There are actually quite a few of them, mostly on the 80's Chevy V8's. You can turn in your Z alternator for the core too.

Just remember, you do need to modify either the alternator or the on-motor bracket to make it fit. You will need to swap on the Z's pulley, keep the 2plug "charge warning" connector unplugged, and run a thick gauge wire straight from the alternator + terminal to + battery terminal, on top of the stock white wire.

I've had the alternator tested two more times now, and it passed once and failed once. The second time it failed, they specifically said the voltage regulator appears to have failed. Looks like I'll be swapping in the turbo alternator this weekend.