2002 GMC Sonoma voltage testing at the fuel pump

Tiny
SCOTT732
  • MEMBER
  • 2002 GMC SONOMA
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 126,000 MILES
How do you check for faulty fuel pump. Can't hear the pump run when the key is turned on. What should voltage readings be at the fuel pump.I have the 5 volts when the key is turned on, but can you check for 12 volts if the truck doesn't run? If so which wire should it be?

Thanks
Scott
Do you
have the same problem?
Yes
No
Sunday, March 30th, 2008 AT 5:37 PM

4 Replies

Tiny
RASMATAZ
  • MEMBER
Direct power to the fuel pump from the battery the Gray wire is the power circuit and black is the ground on the fuel pump connector and see what happens.

Do a voltage drop


http://www.2carpros.com/forum/automotive_pictures/12900_voltage_drop_test_1.jpg

Was this
answer
helpful?
Yes
No
Sunday, March 30th, 2008 AT 6:00 PM
Tiny
SCOTT732
  • MEMBER
I pulled pump. Applied 12 volts. The pump didn't run. Picked up new one. Tried tested it before I put it in. Worked fine. Dosent work in the truck. Applied 12 volts to grey wire and it worked. Took voltage reading at harnes. With key on. Got 3 to 5 volts for a few seconds. Then tried cranking it over. Got the same voltage reading only it was constant. Checked all the fuses under the hood and in the cab. All good. Switched relay with another of the same number. Made no differents.

Any ideas would be greatly appreciated.
Thanks
Scott
Was this
answer
helpful?
Yes
No
Monday, March 31st, 2008 AT 2:37 PM
Tiny
RASMATAZ
  • MEMBER
Check the ECM B fuse and also trun key to On check for power at A8/B8 orange wire should have battery voltage no voltage the problem is coming from the computer. Also check ground on relay connector F7 to chassis ground-
Was this
answer
helpful?
Yes
No
Monday, March 31st, 2008 AT 6:40 PM
Tiny
SCOTT732
  • MEMBER
Rasmataz, I'd like to thank you for your help. It was very usefull. The problem turns out to be in the ground circuit. I plan on tracking it down this weekend.
Thanks again for all your help

Scott
Was this
answer
helpful?
Yes
No
Thursday, April 3rd, 2008 AT 6:36 PM

Please login or register to post a reply.

Recommended Guides