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TIM MOHR
TIM MOHR, ASE MASTER TECH
Category: Chevy
Satisfied Customers: 15961
Experience:  30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
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Low voltage at fuel pump relay plug ( and wire) while

Customer Question

low voltage at fuel pump relay plug (green and white wire) while cranking, Two second prime is 12 volts. only when cranking it drops to 9.4v
JA: How many miles are on the car? Has the car been starting normally?
Customer: 450000
JA: What is the model of your '12 Chevy?
Customer: 1992 chevy silverado
JA: Are you fixing your Silverado yourself? What have you tried so far?
Customer: replaced computer, fuel pump relay,tested wires
JA: Anything else you want the mechanic to know before I connect you?
Customer: i have been replacing parts for a year. oil pressure switch. the truck tries to start if i pour fuel in carb
Submitted: 2 months ago.
Category: Chevy
Expert:  TIM MOHR replied 2 months ago.

Hi, my name is ***** ***** does the battery voltage drop to, when cranking?

Customer: replied 2 months ago.
9.5 volts. when i let off of the key it jumps up to 12v for about a second then to 0v
Expert:  TIM MOHR replied 2 months ago.

ok, thisis either going to be a weak battery, or the starter is drawing too many amps, have you checked the amp draw on the starter yet?

Customer: replied 2 months ago.
new battery. havent checked the starter, cranks fine. I wouldnt know how many amps should be at the starter. starter is only a few years old. very few miles on truck in last 6 years or so.
Expert:  TIM MOHR replied 2 months ago.

the starter will draw about 200 amps, if it is drawing more like 300 amps, it is bad, something in the starter is dropping the volts, it should not go below 11 volt when cranking, its not going to be anything n the fuel pump, if the battery voltage is actually dropping when cranking,Tim