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#1
12-10-2018, 10:03 PM
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OP Gauge issue revisited
1969 GTO, 468 stroker........ car developed an issue with OP gauge not working correctly....... sent gauge to Pete S to rebuild...gauge came back looking great. Upon installing the gauge, it responded well, going to zero with ignition on.
Once the car was started needle went to past 80psi. Needle would go to about half once engine is warmed up....any touch of the gas pedal needle goes to past 80psi. changed op sending unit several times with new and old units...older one seem to work slightly better. Installed a mechanical gauge.....OP was perfect at all times.... With ignition in the on position needle to to past 80psi, once and a while if I wiggle ignition or shift trans back and fourth needle goes to 0 with ignition on. While driving, the op gauge reads perfect at idle like at stoplights or stop signs but once accelerlator is touched needle returns to +80psi. I plan to ask Pete S. very nicely if he would mind checking the gauge again with my supplied op sending units. But before I do that want to check all I can on my end..... seems like when the ignition on position is sending some kind of ground signal to op gauge...... any ideas where I could begin my search for this gremlin ? Thanks....... |
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#2
12-10-2018, 10:12 PM
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Ground issue? What about your printed circuit board, new or original? I think when I did my gauges I added a chassis ground. Just a couple of thoughts...
__________________
The More People I Meet, The More I Love My Dogs! |
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#3
12-10-2018, 11:26 PM
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Wild Guesses based on not enough info: You have two separate problems. 1. Wrong sending unit 2. Fault in the power supply for the gauge--possibly in the ignition switch. A wiring diagram would help to locate the power fault. |
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#4
12-11-2018, 06:56 PM
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#5
12-11-2018, 07:08 PM
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Quote:
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Tried several sending units... plan to send them out to get checked with OP gauge I will try looking in the shop manual to see what wires are are in that switch that could affect op gauge and take a look at those wires when I take the dash out “Perfect oil pressure”... probably wrong term.... reading with mechnical gauge seemed right ... about 80psi when cold.... 30-40psi at idle warm... with a 80lbs Oil pump Thx for your input!! |
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#6
12-12-2018, 05:11 PM
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The shifter wiggle brings two things to mind..
(1) Missing ground strap from engine to firewall. (2) Wires touching/moving when backdrive linkage twists the column. Clay
__________________
All the federales say,they could've had him any day They only let him slip away, out of kindness...I suppose Poncho & Lefty |
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#7
12-13-2018, 11:54 AM
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__________________
The More People I Meet, The More I Love My Dogs! |
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#8
12-16-2018, 01:19 PM
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#9
12-16-2018, 01:46 PM
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Quote:
I did check the blue wire to sending unit noticed, when that wire is unplugged from the sending unit and quickly plugged back, the gauge responds correctly (going to zero) with ignition in the on position for up to two or three on off cycles........then the needle goes back to 80psi as if the wire is grounded or unplugged form sending unit. I was thinking if I remove the harness from the fuse box and run an independent wire from op sending unit to fuse box.....or just run the independent wire to the front of fuse box to the fuse for the op gauge........ Would this help eliminate the blue wire in the harness as the culprit?, even though that harness was installed new about 2 years ago....... thanks........ Last edited by Mook; 12-16-2018 at 02:16 PM. |
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#10
12-23-2018, 09:32 PM
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Update
Took a close look at the plug to OP switch, could see bare wire at the base of the plug. For the past week, the OP gauge has been responding correctly to keying the ignition on and off.
Attempted to sure up the connection with electrical tape. So far gauge still responding to "0" with key on. Will check operation with car running, maybe tomorrow. Thx..... |
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