Voltage
Thread Starter
Racer
Joined: May 2014
Posts: 282
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From: Albany GA
Voltage
Ok. I am still trying to track down intermittent fuel pressure issues. Even with these issues I am running real rich. Another issue working on. While I didn't put 2+2 together before and I thought it was all one issue I think i have two. WOT it drops always has. But I noticed recently when my voltage is high 12's or low 13's its about 50PSI while driving. If its high 13's to 14's its at 59 PSI while driving. Of course WOT drops to 30 for short period until I hit 2PSI an the secondary kicks on. But if the voltage is higher it doesn't drop below 50PSI. So here is the question, is the voltage supposed to fluctuate like this?
Race Director
Joined: Apr 2007
Posts: 11,150
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From: South Western Ontario
Your voltage really shouldn't fluctuate like that. It should be quite steady around 14V. Check the main wiring at the battery, alternator, under hood fuse block and starter. If you don't find anything, then next would be to check the ignition switch. I believe the ignition switch info in in a sticky at the top of the forum.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The ignition switch supplies ALL the "Hot in RUN and START" fuses to all the modules that have memory or have two power sources. Most modules have TWO power sources:
Hot at ALL TIMES & Hot in Run & START
The Hot in Run & START comes from the IGNITION SWITCH outputs. The electrical contacts inside the switch get burnt and can cause lower than desired voltage on that circuits/s
Some times it will be 100% good and it will all of a sudden have a degraded voltage.
Here's a post for your reading pleasure:
- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html
Bill
Hot at ALL TIMES & Hot in Run & START
The Hot in Run & START comes from the IGNITION SWITCH outputs. The electrical contacts inside the switch get burnt and can cause lower than desired voltage on that circuits/s
Some times it will be 100% good and it will all of a sudden have a degraded voltage.
Here's a post for your reading pleasure:
- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html
Bill
Thread Starter
Racer
Joined: May 2014
Posts: 282
Likes: 0
From: Albany GA
The ignition switch supplies ALL the "Hot in RUN and START" fuses to all the modules that have memory or have two power sources. Most modules have TWO power sources:
Hot at ALL TIMES & Hot in Run & START
The Hot in Run & START comes from the IGNITION SWITCH outputs. The electrical contacts inside the switch get burnt and can cause lower than desired voltage on that circuits/s
Some times it will be 100% good and it will all of a sudden have a degraded voltage.
Here's a post for your reading pleasure:
- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html
Bill
Hot at ALL TIMES & Hot in Run & START
The Hot in Run & START comes from the IGNITION SWITCH outputs. The electrical contacts inside the switch get burnt and can cause lower than desired voltage on that circuits/s
Some times it will be 100% good and it will all of a sudden have a degraded voltage.
Here's a post for your reading pleasure:
- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html
Bill
Thread Starter
Racer
Joined: May 2014
Posts: 282
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From: Albany GA
Acct Suspended APR 2026 by request
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2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
datalog it if you can, that will help you track it down... you will be able to see exactly what's happening and when
Thread Starter
Racer
Joined: May 2014
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From: Albany GA
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I use hptuners pro that way I can datalog and also have access to my tune if any changes need to be made
Thread Starter
Racer
Joined: May 2014
Posts: 282
Likes: 0
From: Albany GA
Haven't had much time so it's sat for a bit. Day was so nice I took it out for a bit. On start up voltage over 14. After driving it a few min it steady drops to 12.5 to 13.5. Is this what the ignition switch will do to it if bad? Or is this something else. Just don't want to waste time if it's not the switch.
Thanks
Thanks
Thread Starter
Racer
Joined: May 2014
Posts: 282
Likes: 0
From: Albany GA
Here is the diagnosis procedure for the ignition switch as well as the
removal and repair:
diagnosis
http://forums.corvetteforum.com/1568186703-post64.html
removal
http://forums.corvetteforum.com/1571067145-post107.html
repair procedure
http://forums.corvetteforum.com/c5-t...ch-repair.html
removal and repair:
diagnosis
http://forums.corvetteforum.com/1568186703-post64.html
removal
http://forums.corvetteforum.com/1571067145-post107.html
repair procedure
http://forums.corvetteforum.com/c5-t...ch-repair.html
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
It could be good one ignition cycle or one day or one week and bad for 30 minutes. Unless your repair or replace the switch, its a crap shoot.
If you are having LOW voltage issues on the HOT in Run & Start ignition switch supplied buss,, fix or replace the switch.
Bill
Thread Starter
Racer
Joined: May 2014
Posts: 282
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From: Albany GA
Ok so I took it out the other day and it did have burnt contacts my buddy had a brand new one he let me have for 40 bucks so I said sure. Put it in and all went well. The voltage still goes between 13.3 and 13.9 but before it would stay steady after a few min at 13.1 or little lower. The fuel pressure is steady at 58psi at idle when before it was between 45 and 53 at idle. It does still drop to about 45 before 2psi when the secondary kicks in but once I let off its right back at 58. I have not driving more the 15 min yet but could the voltage fluctuations be the alternator?
The instructions were great took me about an hour. Thank you so much for them!
The instructions were great took me about an hour. Thank you so much for them!
Last edited by joewom; Mar 23, 2015 at 08:24 PM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
If you are using the IPC voltmeters as a voltage refference,,, DONT! Its NOT an actual battery voltage measurement.
The ONLY TRUE battery voltage measurement is one taken directly on the battery terminals with a volt meter.
Even at the voltages that you are seeing on the IPC meters are fine and YES,, the alternator will vary charging voltage internally to suit battery charging needs.
Quote
" It does still drop to about 45 before 2psi when the secondary kicks in but once I let off its right back at 58."
What SECONDARY are you refering to??????
Bill
The ONLY TRUE battery voltage measurement is one taken directly on the battery terminals with a volt meter.
Even at the voltages that you are seeing on the IPC meters are fine and YES,, the alternator will vary charging voltage internally to suit battery charging needs.
Quote
" It does still drop to about 45 before 2psi when the secondary kicks in but once I let off its right back at 58."
What SECONDARY are you refering to??????
Bill
Thread Starter
Racer
Joined: May 2014
Posts: 282
Likes: 0
From: Albany GA
If you are using the IPC voltmeters as a voltage refference,,, DONT! Its NOT an actual battery voltage measurement.
The ONLY TRUE battery voltage measurement is one taken directly on the battery terminals with a volt meter.
Even at the voltages that you are seeing on the IPC meters are fine and YES,, the alternator will vary charging voltage internally to suit battery charging needs.
Quote
" It does still drop to about 45 before 2psi when the secondary kicks in but once I let off its right back at 58."
What SECONDARY are you refering to??????
Bill
The ONLY TRUE battery voltage measurement is one taken directly on the battery terminals with a volt meter.
Even at the voltages that you are seeing on the IPC meters are fine and YES,, the alternator will vary charging voltage internally to suit battery charging needs.
Quote
" It does still drop to about 45 before 2psi when the secondary kicks in but once I let off its right back at 58."
What SECONDARY are you refering to??????
Bill