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RPM & Oil Pressure sensor

Old 10-12-2018, 04:23 AM
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ZEROVETTE7
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Default RPM & Oil Pressure sensor

Have two issues:
1- got me a new oil pressure sensor and switch (old one leaking) both come on the Tee in the back of the engine below the dist. Does the FSM show how to connect which wires? Which section in the manual? I couldnít find it.

2- RPM doesnít move at all (photo attached) stays there all the time on or off. What could be the problem and how to solve it?



Thanks
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Old 10-12-2018, 04:33 AM
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Forgot to mention the ride is 1991 L98 auto (stock.
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Old 10-12-2018, 09:08 AM
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Tach should park @ 0 when ignition is 'KEYED ON' - 'NOT RUNNING'. If the Tach isn't properly calibrated then it could/can wander but not usually as you've pictured. That snapshot looks to have been done with key in your pocket. Tach wire disconnected @ the distributor would be the first check. Are you familiar with the 'WHITE' wire @ the HEI distributor? If the WHITE is connected correctly @ the HEI then a 'busted' wire in the circuit somewhere. Tach filter if stock would be bolted to the rear of the LH cylinder head. Check it for connections.

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Old 10-12-2018, 09:13 AM
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Originally Posted by WVZR-1 View Post
Tach should park @ 0 when ignition is 'KEYED ON' - 'NOT RUNNING'. If the Tach isn't properly calibrated then it could/can wander but not usually as you've pictured. That snapshot looks to have been done with key in your pocket. Tach wire disconnected @ the distributor would be the first check. Are you familiar with the 'WHITE' wire @ the HEI distributor?
wheathet on or off or running the needle stays down there! Doesnít move.
As for the WHITE wire you mentioned , no Iím not familiar.
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Old 10-12-2018, 09:24 AM
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Originally Posted by ZEROVETTE7 View Post


wheathet on or off or running the needle stays down there! Doesnít move.
As for the WHITE wire you mentioned , no Iím not familiar.
If distributor is stock you should have no trouble finding it. Perhaps someone with an early HEI has a snapshot saved and can post it.
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Old 10-12-2018, 09:39 AM
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All stock but the cap replaced.
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Old 10-12-2018, 12:03 PM
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Originally Posted by ZEROVETTE7 View Post
All stock but the cap replaced.
That could explain 'maybe' your issue. When you did the cap you maybe failed to reconnect the tach lead! Look in the 6D4 section of the FSM and there's distributor images that could help you.

The OPS? Your '91 I believe is a single component with 3 wires. Is this correct? You have the new part? Brand and part number maybe.

I saw a post the other day where someone mentioned removing the wiper motor to service that area of the engine. In that thread it was suggested to pull the distributor 'next time'. I've never owned an L98 but it seems likely that if you removed cap and rotor maybe it is an easier reach. I have no idea!!

REMEMBER NOW THAT I'VE NEVER OWNED AN L98 !!!!!!! Never serviced one in a C4 either! In an F-body yes.

Here is the thread where it was mentioned:

https://www.corvetteforum.com/forums...post1598115656

Last edited by WVZR-1; 10-12-2018 at 12:12 PM.
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Old 10-12-2018, 12:05 PM
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Default you can see where the white wire goes 1986


This is all I got - Left hand of the dizzy looking aft
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Old 10-12-2018, 03:43 PM
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Iíll look for the white wire and check the FSM. Thx
as for the OPS I got the new parts as shown in the photos with the part no.



The short one with one pin and three slots. The long one with 3 pins. Just wanna know which wires goes to which as I wasnít the one who removed them.
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Old 10-12-2018, 06:36 PM
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Single pin I'd think is LT BLU (8A50-4). That switch lights the 'CHECK GAUGES' when LOW OIL PRESSURE.

The 3 pin connector should have 3 wires I'd think (TAN,ORANGE & RED) in one connector. (8A20-6) This is for the GAUGE (TAN), FUEL SWITCH (RED & ORANGE)

Your part numbers look to be the current sold by ACD.
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Old 10-15-2018, 04:34 AM
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Originally Posted by WVZR-1 View Post
Single pin I'd think is LT BLU (8A50-4). That switch lights the 'CHECK GAUGES' when LOW OIL PRESSURE.

The 3 pin connector should have 3 wires I'd think (TAN,ORANGE & RED) in one connector. (8A20-6) This is for the GAUGE (TAN), FUEL SWITCH (RED & ORANGE)

Your part numbers look to be the current sold by ACD.
got the diagrams from the FSM. Thanks a lot.
Will get into it and update if faced any issues...
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