Fuel pump not working?

Tiny
TPMPRODUCTIONS
  • MEMBER
  • 2006 BUICK RENDEZVOUS
  • 3.5L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 306,874 MILES
Well, I lost power to my fuel pump about a week ago. After buying a brand new one, putting it in, still not starting. No power to the pump. Now after putting the battery back in (I share the battery with my other car), I have no lights along with not starting. I changed the fuse and relay before changing the pump. Then I got a test light. Test light tells me that, at the body harness under the driver's seat, that I got no live wires going to the pump. Also, no power to the fuse box where the relay goes.I checked other spots and got the test light to light up. Fuel pump, no good. With the key off and with it on. Someone please help. I'm new at mechanic work, but willing to do the work.
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Saturday, June 6th, 2020 AT 9:43 PM

55 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

When you say there is no power to the fuel pump relay, is there power to the fuse which supplies it? See pic 1. If not, let me know if any of the fuses in pic 2 have power.

Joe
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Sunday, June 7th, 2020 AT 12:10 AM
Tiny
TPMPRODUCTIONS
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Yes the fuel pump fuse has power. Or I mean, it lights up when I put the test light to it.
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Tuesday, June 9th, 2020 AT 7:40 PM
Tiny
TPMPRODUCTIONS
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I got power to all the other fuses, just not that one. The fuel pump relay has no power. I was just on another site (which I will not name) that makes you pay for their "experts" and the gentleman told me I needed a new fuse box. Needless to say after I replaced the fuse box (today) I'm having the same problem. I'm sure it's something that I don't know about, like a connection that I'm not thinking of.
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Tuesday, June 9th, 2020 AT 7:51 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

No, you're not missing anything. Take a look at the pic below. I need to confirm that there is power to the fuse indicated. Next, the dark green wire with a white tracer is from the PCM. That is what energizes the relay to power the pump. You need to check if it is getting power. If it is, last is the gray wire that sends power to the pump. Check it for power.

___________________________

Next, here is a diagnostic flow chart for diagnosing electrical issues related to the fuel pump. Pictures 2 and 3 are the actual steps. I don't know if you are comfortable doing this, but I wanted to add it.

___________________________

2006 Buick Truck Rendezvous FWD V6-3.5L VIN L
Fuel Pump Electrical Circuit Diagnosis
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Testing and Inspection Component Tests and General Diagnostics Fuel Pump Electrical Circuit Diagnosis
FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS
FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS

CIRCUIT DESCRIPTION
When the ignition is turned ON, the powertrain control module (PCM) turns ON the fuel pump relay, which turns ON the in-tank fuel pump. The in-tank fuel pump remains ON as long as the engine is cranking or running and the PCM is receiving reference pulses. If there are no reference pulses, the PCM turns the in-tank fuel pump OFF 2 seconds after the ignition is turned ON or 2 seconds after the PCM no longer receives reference pulses.

DIAGNOSTIC AIDS
- Inspect the ground connection for the fuel pump. Ensure all ground connections are clean and tight.
- The following conditions may have caused the fuel pump fuse to open:
- The fuse is faulty.
- There is an intermittent short in the fuel pump power feed circuit.
- The fuel pump has an intermittent internal problem.
- For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections. See: Vehicle > Component Tests and General Diagnostics

TEST DESCRIPTION

Step 1 - Step 14

See pic 2

Step 15 - Step 27

See pic 3

The numbers below refer to the step numbers on the diagnostic table.
3. This step determines if the condition is located on the coil side or the switch side of the circuit.
4. This step verifies that the PCM is providing voltage to the fuel pump relay.
5. This step tests for an open in the ground circuit to the fuel pump relay.
6. This step determines if a voltage is constantly being applied to the fuel pump relay.
13. This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.

_______________________

Let me know if this helps or what you find.

Joe
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Tuesday, June 9th, 2020 AT 9:06 PM
Tiny
TPMPRODUCTIONS
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First of all, before I get into the pictures that you've sent, I just want to say thank you because you've already helped me more than the guy on the other site. All he keeps saying is, "I can give a diagram for that fuel pump and fuse box. I'm starting to wonder if this guy is even an expert.
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Tuesday, June 9th, 2020 AT 11:55 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
You are very welcome. I'll try my best to help. Wiring issues can be a bit tricky simply because they can occur anywhere in the system. I have actually had the wire break under the insulation. You can't tell it is broken until you actually touch the specific spot. So, lets give this a try and see if we can figure it out together.

Take care,
Joe
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Wednesday, June 10th, 2020 AT 8:39 AM
Tiny
TPMPRODUCTIONS
  • MEMBER
Getting ready to work on my car. Can I use the test light to probe the (green) wire for the PCM to see if it gets power or do I have to check at the end? I'm new to this mechanic thing but I'm learning.
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Wednesday, June 10th, 2020 AT 3:59 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
You can, but I believe it sends a 5v reference signal, so the light may be dim.

Let me know.
Joe
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Wednesday, June 10th, 2020 AT 9:17 PM
Tiny
TPMPRODUCTIONS
  • MEMBER
Okay, so no power to the PCM.
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Thursday, June 11th, 2020 AT 10:00 PM
Tiny
TPMPRODUCTIONS
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I'm starting to think that's the problem.
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Thursday, June 11th, 2020 AT 10:00 PM
Tiny
TPMPRODUCTIONS
  • MEMBER
I also have no power to the PCM relay or both fuses.I took it apart and cleaned it (it was very dirty), the PCM that is, and checked the connections. They all looked fine. I cleaned the wires and sprayed the connectors with connector cleaner and still no power. I'm thinking the PCM has gone bad. I'm going to get a better code reader later.
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Friday, June 12th, 2020 AT 5:29 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

When you checked for power at the fuse, did you have the key in the run position? Did you check both sides of the fuse? If there is no power there, we have to look further into the issue. The PCM sends the signal to the relay, which energizes it, thus allowing the power from the pump fuse to power the pump.

Let me know how you checked the fuel pump fuse and if it is the exact same way it was originally. Also, I realize you cleaned and inspected items. Did you check the connections at the fuse box?

Let me know.
Joe
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Friday, June 12th, 2020 AT 10:19 AM
Tiny
TPMPRODUCTIONS
  • MEMBER
So I check in both on and off positions. The fuel pump fuse (10A) works. The relay gets no power. The connections at the fuel pump are fine. I changed the fuse box the other day. The connections at the PCM are fine. The PCM relay fuse and PCM sensor fuse do not have any power to them. Neither does the PCM relay. So what I'm saying is, the PCM is getting no power at the fuse box. The green and white wire also has no power. I recall you telling me to check that as well.
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Friday, June 12th, 2020 AT 11:50 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Is it the under hood fuse box that was replaced? Are the three fuses in the attached pic good and have power to them?

Let me know. If they are not getting power and you replaced the fuse box, it doesn't make sense. Is the replacement fuse box new or used?

Joe
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Friday, June 12th, 2020 AT 10:49 PM
Tiny
TPMPRODUCTIONS
  • MEMBER
Okay so, I'm not at my car right now, but I will go check in the morning. To answer the questions, yes I changed the under hood fuse box (as per the "expert") on the other site. Once I changed it, I had the same issue; no power to the fuel pump and no lights. The guy told me the fuse box had the exact same issue as the last one. The fuse box is used. It was from a 2005 Buick Rendezvous Ultra with 123,989 miles on it. The engine was a 3.6 so the fuse boxes matched. Now the IGN 1 and ignition fuse both get power. I'll check the other one.
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Saturday, June 13th, 2020 AT 2:30 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Let me know what you find.

Joe
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Saturday, June 13th, 2020 AT 6:42 PM
Tiny
TPMPRODUCTIONS
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Okay, so I got power to all three fuses.
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Saturday, June 13th, 2020 AT 11:43 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Okay, if the fuses are good, I need you to check power to pin 19 in the harness to the PCM. See attached pic. If there is power there, connect the PCM and check for power out from pin 37. If there is no power, then it's related to the PCM. If there is no power to pin 19, you have an open circuit between the ignition 1 fuse and the PCM.

Let me know.

Joe
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Sunday, June 14th, 2020 AT 4:15 PM
Tiny
TPMPRODUCTIONS
  • MEMBER
Okay, so let's go back a little bit. Something didn't sit right with me about the fuses I checked the other night so I brought my shop light with me and it turns out I checked the wrong fuse when you asked me to check the ignition fuse and relay. Turns out, I have no power to the ignition main fuse.
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Sunday, June 14th, 2020 AT 9:27 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

If you aren't getting power to the 60 amp ignition fuse, something is wrong with the fuse box. The power comes direct from the battery into the box and then is fused (60 amp) to other things. So, power is being lost between the battery and the fuse. Take a look at the pic I attached. It shows one power supply from the battery introduces power to multiple fuses. The ignition 1, 60 amp fuse is one of them. Do the other fuses around the Ignition 1 fuse have power?

Let me know.
Joe
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Sunday, June 14th, 2020 AT 10:02 PM

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