![]() |
![]() |
#1 |
Registered User
Join Date: Sep 2011
Location: Dannebrog NE
Posts: 125
|
Voltage Issue
I have an 85 c10. It has the TBI engine switched out for a carbed SB. I have moved the battery to the bed and the power cable straight to the starter. It has a 3 wire alternator that I had tested at two different places to make sure it is good. The problem I am having is when the truck is running my volt meter is pegged out past 18 volts. I bought a second volt meter to make sure mine wasn't bad, and it also pegs out past 18 volts. What would cause my volts to be so high??? Is it a possible starter issue, a wiring issue? Any help would be great.
__________________
Marcus 1985 swb C10 Supercharged357/TH400 1972 lwb C20, Grandpa Al's Truck |
![]() |
![]() |
![]() |
#2 |
Moderator
![]() Join Date: Oct 2008
Location: Wentworth, NH
Posts: 4,951
|
Re: Voltage Issue
TBI started in 1987. The stock 1985 engine should have a Rochester electronic feedback carburetor... Or do you mean you have an 87 or later engine with the original carb?
On to the real question... It's likely a wiring issue. The SI series alternator #2 sense lead should be connected to the battery at the 3/8" starter BAT terminal via a fusible link. It could overcharge if this connection is not made. Did you hook up the two fusible link wires at the 3/8" BAT terminal on the starter? Are either of those fusible links damaged? With the engine off... What does a voltmeter read at the battery and at the J-block stud on the firewall to the engine?
__________________
1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...
And please let us know if and how your repairs were successful. Last edited by hatzie; 10-24-2015 at 09:47 AM. |
![]() |
![]() |
![]() |
#3 |
Registered User
Join Date: Sep 2011
Location: Dannebrog NE
Posts: 125
|
Re: Voltage Issue
With the engine off it shows 12ish volts. I have investigated the wiring and it is all shorts of hacked up. The fusible link wires are no longer on the truck. I am going to have to rewire some of the wiring harness that has been cut into and spliced. I found that a lot of the stuff added in the wiring system before I bought the truck didn't have fuses so I am out a tachometer, a electric fan and possible the coil in my distributor.
__________________
Marcus 1985 swb C10 Supercharged357/TH400 1972 lwb C20, Grandpa Al's Truck |
![]() |
![]() |
![]() |
#4 |
Registered User
Join Date: Aug 2012
Location: Oklahoma City, OK
Posts: 2,541
|
Re: Voltage Issue
As a test, jumper from the sense wire to the output post on the alternator. If your volts drop to 13~14, your current sense connection is bad. If they stay at 18+, your voltage regulator is likely toast.
|
![]() |
![]() |
![]() |
Bookmarks |
Thread Tools | |
Display Modes | |
|
|