fuel pump not working
Thread Starter
Heel & Toe
Joined: Mar 2012
Posts: 24
Likes: 0
fuel pump not working
My 93 c4 sat for 10 yrs. Dug it out ,put injectors in it, cleaned the tank, ran fine for 20 miles. Now it wont run. Checked the fuel pump fuses & pump but it wasn,t pumping. Checked the previous pump seperately, works fine. I could use some help w/this,THNX
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
First thing I would do since you checked the fuse, is to check for voltage back at the pump. Pull out that rubber surround at the filler cap so you can get to the electrical connector. The fuel pump power wire should show 12 volts for approx 2 seconds after you turn the key to on, then it will go to O volts. If you have voltage and a good ground, then it's time to pull the pump. I believe the tan/white wire is the 12 volts positive and ground is black. The other wire should be the fuel sending unit. There is a fusible link and a relay to check at some point, but that is where I would start. Good luck.
P.S. you would have gotten more responses in the Tech/Performance section. And, I don't know how you determined the pump was not pumping. You also said nothing about the 10 year old fuel filter. It's behind the right front tire. These instructions were based on my 91 vette, they should be very similar if not identical to the 93.
P.S. you would have gotten more responses in the Tech/Performance section. And, I don't know how you determined the pump was not pumping. You also said nothing about the 10 year old fuel filter. It's behind the right front tire. These instructions were based on my 91 vette, they should be very similar if not identical to the 93.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
After checking to make sure there is voltage at the pump harness, you will also need to check the fuel pressure at the rails. Connect a fuel pressure gauge at the Schroeder valve, turn the key to ON and see what the reading is. You may need to repeat that a few times as the pump will only run for 2 seconds if the engine isn't started.
A good working pump, a clean "sock" at the pickup, a clean fuel filter and lines that are not clogged should provide around 40 lbs of pressure and pressure should remain for awhile.
A good working pump, a clean "sock" at the pickup, a clean fuel filter and lines that are not clogged should provide around 40 lbs of pressure and pressure should remain for awhile.
