# Fuel pump refuses to work **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** chevrolet, blazer\ **Created:** [October 16, 2020, 8:18pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270 "2020-10-16T20:18:46Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![owen9fn](https://avatars.discourse-cdn.com/v4/letter/o/cc9497/32.png) [@owen9fn](https://community.cartalk.com/u/owen9fn)\ **Post date:** [October 16, 2020, 8:18pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/1 "2020-10-16T20:18:46Z")
I have been struggling to make this thing work. We have replaced the fuel pump with brand new ones twice now, replaced the FP relay, tested the voltage, ohms, and amperage under load and with out, and have tested the pump directly hooked to the battery and it works. For the life of me I can’t figure out what is going on. Any help would be appreciated ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 16, 2020, 8:28pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/2 "2020-10-16T20:28:02Z")
How can anyone help if we don’t know the year of this Blazer? Tester ---
**Author:** ![owen9fn](https://avatars.discourse-cdn.com/v4/letter/o/cc9497/32.png) [@owen9fn](https://community.cartalk.com/u/owen9fn)\ **Post date:** [October 16, 2020, 8:30pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/3 "2020-10-16T20:30:52Z")
It’s an 02, sorry. I forgot to put that in the info. ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [October 16, 2020, 8:34pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/4 "2020-10-16T20:34:42Z")
Let’s be absolutely clear on something 2002 Chevy Blazer 4.3 V6 . . . ?! or is it a 2002 Chevy TrailBlazer 4.2 inline 6 . . . ?! I’m asking because some people use the word Blazer, when in fact they meant Trailblazer it sounds like the pump isn’t getting a signal to energize . . . ---
**Author:** ![owen9fn](https://avatars.discourse-cdn.com/v4/letter/o/cc9497/32.png) [@owen9fn](https://community.cartalk.com/u/owen9fn)\ **Post date:** [October 16, 2020, 8:36pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/5 "2020-10-16T20:36:33Z")
It’s a Blazer 4.3 v6. As far as I know it is getting power. A buddy just told me to try and run a new ground, worth a shot after doing everything else ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 16, 2020, 8:37pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/6 "2020-10-16T20:37:21Z")
The powertrain control module controls the function of the fuel pump relay. ![image](https://global.discourse-cdn.com/cartalk/original/3X/6/b/6bd4430b2f710a2c89d1c93482a14ad23eed8721.png) Tester ---
**Author:** ![owen9fn](https://avatars.discourse-cdn.com/v4/letter/o/cc9497/32.png) [@owen9fn](https://community.cartalk.com/u/owen9fn)\ **Post date:** [October 16, 2020, 8:42pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/7 "2020-10-16T20:42:53Z")
The pcm is good, I get power to the connector at the pump but under a load it’s no good. ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [October 16, 2020, 8:42pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/8 "2020-10-16T20:42:55Z")
> [@owen9fn](#): > > As far as I know it is getting power. Exactly what does that mean? Does it mean you’ve verified . . . for example with a 12V test light and/or digital multimeter . . . that the fuel pump is getting power? Or does it mean you assume the pump is getting power? ---
**Author:** ![owen9fn](https://avatars.discourse-cdn.com/v4/letter/o/cc9497/32.png) [@owen9fn](https://community.cartalk.com/u/owen9fn)\ **Post date:** [October 16, 2020, 8:43pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/9 "2020-10-16T20:43:39Z")
We verified with a multimeter and test light ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [October 16, 2020, 8:45pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/10 "2020-10-16T20:45:12Z")
> [@owen9fn](#): > > I get power to the connector at the pump but under a load it’s no good Sounds like you’re going to have use a multimeter to find out where the voltage drop is Could be bad connections at an intermediate connector, fuel pump relay contacts, etc. I wouldn’t at all be surprised if the bad connection . . . burnt brittle, for example . . . is inside the fuse box itself. I’ve seen this a few times ---
**Author:** ![owen9fn](https://avatars.discourse-cdn.com/v4/letter/o/cc9497/32.png) [@owen9fn](https://community.cartalk.com/u/owen9fn)\ **Post date:** [October 16, 2020, 9:04pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/11 "2020-10-16T21:04:02Z")
I’ll hunt around for something like that, hopefully it’s not too deep in there. I just talked with some one and they said it could potentially be the ground from the ignition, does that seem like a possibility? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 16, 2020, 9:06pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/12 "2020-10-16T21:06:02Z")
I’d be looking at ground G402 as shown in the wiring diagram. Tester ---
**Author:** ![owen9fn](https://avatars.discourse-cdn.com/v4/letter/o/cc9497/32.png) [@owen9fn](https://community.cartalk.com/u/owen9fn)\ **Post date:** [October 16, 2020, 9:50pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/13 "2020-10-16T21:50:50Z")
I cut the ground and wired it to a bolt on the frame and… She Runs! Now to just put it all back together. ---
**Author:** ![oldnotdeadyet](https://avatars.discourse-cdn.com/v4/letter/o/a6a055/32.png) [@oldnotdeadyet](https://community.cartalk.com/u/oldnotdeadyet)\ **Post date:** [October 17, 2020, 6:55pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/14 "2020-10-17T18:55:05Z")
I believe that all you have proved is that the ground is not being established when it should have been. You need to find out why that is. Otherwise, your pump will not be disconnected from ground when it should. (Is the ground controlled by computer? (“Tester” obviously understands this better than I do.) ---
**Author:** ![owen9fn](https://avatars.discourse-cdn.com/v4/letter/o/cc9497/32.png) [@owen9fn](https://community.cartalk.com/u/owen9fn)\ **Post date:** [October 17, 2020, 7:00pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/15 "2020-10-17T19:00:04Z")
That’s what the relay is for. It doesn’t send the power unless it’s asked for. Where it’s grounded shouldn’t matter. ---
**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\ **Post date:** [October 17, 2020, 8:12pm UTC](https://community.cartalk.com/t/fuel-pump-refuses-to-work/171270/16 "2020-10-17T20:12:34Z")
I suspect the problem with the ground connection is in the splice pack SP423 as shown in the drawing. Bad connections can seem to be okay until a good load is placed on the line. Using a meter or test light to check for power can fool you at times since they don’t require much current to make them operate. Using something a brake light or head light would help show up a bad connection since they require more current to run them. Like you say, the ground side of the circuit is tied to ground at all times. The FP relay controls the ‘hot’ or power side of the circuit in order to turn the pump on or off.