2002 Chevy Blazer Fuel pump

Tiny
DIRTMAN616
  • MEMBER
  • 2002 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
Fuel pump issues. Check engine light was on, after reading code, got a new gas cap and light went off. Two days later vehicle died. Fuel pump wouldn't come on. Got a new fuel pump and plugged both terminals in and now new one won't run. I only have a test light but I do get very weak power to one of the prongs on the pump terminal (not the sending unit terminal). Fuse not blown-ECM-B- and I did try switching around some relays with no success. I do have power and ground at relay as I checked it with key on and key off but I am not really sure what its supposed to be. Does the fuel pump need to be installed or grounded to work? I wanted to make sure it was going to function properly before I put it all back together.
Thanks
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Wednesday, September 15th, 2010 AT 2:16 PM

7 Replies

Tiny
JDL
  • EXPERT
You need to get a meter so you can read actual voltage. I've seen digital multimeter meters in discount stores, not very high, better than nothing.

I don't know what testing you have done? I'd have to start from scratch. Make sure the battery has a full charge. Use a gage and check fuel pressure, engine cranking, right now, I don't care about the initial prime. Some of the national brand autostores used to loan out a fuel pressure gage, if you don't have one. Check for applicable trouble codes, at the least, you need an obd2 code reader. If it turns out the problem is other than a fuel issue, me and you are just spinning our wheels. A no load test on a fuel pump isn't worth much, I've seen pumps run just fine on the bench, wouldn't run with a load, though.

In the diagram, the gray wire at the relay, carries voltage for the pump. If you unplug the relay and use jumper wire with inline fuse from battery to terminal for the gray wire, the pump should run, no need to use the key.


http://www.2carpros.com/forum/automotive_pictures/170934_2002_43L_1.jpg

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Wednesday, September 15th, 2010 AT 3:14 PM
Tiny
DIRTMAN616
  • MEMBER
Thanks JDL.
I did check pressure at schrader valve before I removed the pump. No pressure. I did run the truck for two days and everything was fine after I put a new gas cap on it and the check engine light went out. Then it died. Can I check again for codes while the engine is not running with just the key turned on? I will try jumping the wire to the fuel pump terminal gray wire and see what happens and I'll have to get a volt meter to see how much power is back there.
Tx,
Dirtman616
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Wednesday, September 15th, 2010 AT 3:55 PM
Tiny
JDL
  • EXPERT
I'd get a digital multimeter. The dark green wire with white tracer at the relay is voltage for the coil side of relay. At initial prime, key on, no crank, the circuit would be hot only for a few seconds, then go dead without rpm signal. Engine cranking, that wire should be hot all the time, maybe low voltage because it comes from the computer, use digital multimeter to check.
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Wednesday, September 15th, 2010 AT 4:10 PM
Tiny
DIRTMAN616
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Please. Will the fuel pump run while plugged in but not fully installed in the tank and fully installed on the vehicle?
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Saturday, September 18th, 2010 AT 3:44 PM
Tiny
JDL
  • EXPERT
I'd keep it away from any gas fumes, but, yes it should run. Be safe.
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Sunday, September 19th, 2010 AT 9:36 AM
Tiny
DIRTMAN616
  • MEMBER
How do I get the relay box apart so I can check all the stuff you said to check? Also, is there any grounds that I need to check and what is that box/unit that is on the cross member just in front of the tank that a plug-in goes to on the front side of the cross member? Is that the fuel pump /pressure- oil pressure switch?
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Sunday, September 19th, 2010 AT 2:51 PM
Tiny
DIRTMAN616
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I got about 5 volts on gray with white stripe prong at fuel pump terminal.
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Sunday, September 19th, 2010 AT 3:31 PM

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