Put in $30 worth of premium and gauge went to Empty

[RC92234]

Car went to the shop for tuning, replace gas tank & sender and other work.  They gave me back my car with about 1/4 of a tank showing on the gauge. Before the new sender, it only ever registered Empty.  A few short drives around the 'hood over a few weeks and the tank was again approaching E so drove down and put $30 worth in (at $4.59/gal, was about 5-6 gallons).  After the shop visit, all gauges (including fuel!) were working great.

After getting gas and starting the car up, the gauges were seemingly DOA.  Fuel gauge:  less than empty.  Oil: no pressure.  Ammeter: no movement.  Temp:  below "C" (and I'd driven around a bit before getting gas so car was easily warm).  Drove home -- no change.  No pressure, no juice, no temp and looked like no gas.  As I pulled into the driveway, I was already composing this post.

Turned the car off and got out, then something told me to start it again so I did.  All gauges registered normally!  1/2 tank gas, medium oil, slight positive juice, firmly middle of the gauge temperature. 

What's up with this?

 

[Stanglover]

Well, I'm definitely not the electronics guy to ask, but maybe a loose ground wire somewhere that's making intermittent contact. 

 

[Don C]

The common factor for all gauges, other than the ammeter, is the instrument voltage regulator. Old ammeters are notoriously lacking in movement.

Your ignition switch may not have been making contact on the accessory feed contacts or you may have a loose wire, either voltage feed or ground to the IVR. When it happens again, try jiggling the ignition switch.

 

[RC92234]

44 minutes ago, Don C said:When it happens again, try jiggling the ignition switch.

Thanks - will do!

 

[RC92234]

Don C hit a bingo on this one.  For engine, seems the key can be anywhere between OFF and START (3/8"? of play), but for gauges, the correct alignment is right up next to where the resistance begins before START.

 

[tony-muscle]

The common factor for all gauges, other than the ammeter, is the instrument voltage regulator. Old ammeters are notoriously lacking in movement.

Your ignition switch may not have been making contact on the accessory feed contacts or you may have a loose wire, either voltage feed or ground to the IVR. When it happens again, try jiggling the ignition switch.

+1

It has happened to me a few times. I just need to rotate the key back a little for the needles to move again.

 

[Stanglover]

Sounds like time for a new ignition switch!!

 

[RC92234]

Sounds like time for a new ignition switch!!

Is it the ignition lock cylinder or the ignition switch that needs to be replaced?  Seems if jiggling the key into the just right position solves the problem, then it would be the lock cylinder, not the switch, but the lock cylinder has no electrics just a rod that goes to the switch.

 

[Don C]

Jiggling the key moves the rod that moves the switch. Either your switch needs adjusting or you need a new one. The grease in the switches dries out, which makes it difficult for the slide in the switch to move, and also gums up the contacts, so jiggling it can make it move that last fraction of an inch to make contact.

 

[RC92234]

Alrighty then, I replaced the switch.  Gauges still don't work.  With a new switch in place, the key movement is pretty firm, that is, no jiggle.  So there's no toying with the key to make gauges wake up.  Car starts, operates as expected through all the key positions.

I did also replace all the dash lights and the IVR; didn't like the level of brightness so replaced them again (will see tonight if the 5x brighter does the trick), and then I replaced the ignition switch.  The lock cylinder, for now, is still original.

Did I miss something with the IVR?  It looks pretty simple and there's only one place for it.   It just screws in and there's nothing else to hook up.

Barring that, other suggestions?

 

[Don C]

Do your accessories, like heater, radio, and turn signals work? They receive power from the same circuit that feeds the instrument voltage regulator. As has been stated many times on this forum, new does not mean good, lots of parts are bad out of the box. Were you careful when you pulled the old IVR off the printed circuit, doesn't take much to break the 50 year old printed circuit. Did the new IVR make good connections to the printed circuit?

 

[RC92234]

Yes, heater, radio & blinkers all work fine.

I was planning to change to LEDs so I started with replacing the printed circuit, followed by new IVR and then bulbs.

How would I test if the IVR was making good connections? Seems garages not working would say “no”.  It screws into place on the circuit and also connects to a 9-volt type connection. Everything is snug.

I still have the old IVR which was working so I could put it back in for testing, and I have an extra new IVR because I over-ordered.

Update: Since the question was IVRs, while I awaited an answer, I pulled the instrument cluster, removed and examined the IVR (no issues) then reinstalled it.  Really, I did nothing but remove it, look it over and put it back (did not remove from the 9-v connection, just the screw holding it to the cluster).  And now everything works fine!

Bravo, Don -- many thanks.

 

[midlife]

Do your accessories, like heater, radio, and turn signals work? They receive power from the same circuit that feeds the instrument voltage regulator. As has been stated many times on this forum, new does not mean good, lots of parts are bad out of the box. Were you careful when you pulled the old IVR off the printed circuit, doesn't take much to break the 50 year old printed circuit. Did the new IVR make good connections to the printed circuit?

The IVR power comes directly from the ignition ACC via a resistor wire and is NOT part of the same circuit (fused) as the radio, backup lights, and washer motor.  Turn signals are also ACC powered, but not part of the resistor wire system.  The resistor wire starts at the main power for the wiper switch, however. 

 

[Don C]

The point is, they all come from the same connector on the ignition switch, and if the accessories work the IVR circuit will also be getting voltage. So, the problem is either in the circuit (connectors, resistor wire, printed circuit) leading to the IVR, or in the IVR. 

It also means the ignition switch is adjusted correctly.

 

[RC92234]

It also means the ignition switch is adjusted correctly.

And now there is none of the jiggle in the ignition lock cylinder, i.e., "where the key goes" - hooray! 

Will still eventually swap it out since doors don't unlock with the ignition key.  I've always been reluctant to lock a convertible because leaving it unlocked hopefully prevents someone from tearing through the top to get in the car.

 

[midlife]

Was this car originally from Las Vegas?  I ask since putting in $30 and getting nothing in return is common in that neck of the woods...