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Matt J
Matt J, Chevy Technician
Category: Chevy
Satisfied Customers: 1399
Experience:  10+ years automotive tech, 5 years of experience in a GM dealer
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1997 Chevy Silverado 1500: V8..key switch..the fuel pump

Customer Question

I have a 1997 Chevy Silverado 1500 truck with the 5.7liter V8. It has problems starting and I noticed that when the key switch is turned on the fuel pump is not pumping. After cranking for a while the engine starts and after it is running the engine stops if I unplug the fuel pump relay. I checked the relay and it is good and the fuel pump is 18 months old. Any suggestions?
Submitted: 8 years ago.
Category: Chevy
Expert:  Matt J replied 8 years ago.

Hello my name is XXXXX XXXXX I will be more than happy to assist you.

 

To verify the cause a few test will need to be done. Do you have a Test Light, if not could you get one. Most auto parts stores have them and cost is about $5-$20

Customer: replied 8 years ago.
Yes I have a test light, not with me as I am at work.
Expert:  Matt J replied 8 years ago.

Once you are able to do the testing this is what I want you to test.

 

With the ignition on use the test light and test for power at this fuses. The fuses are located in the fuse block under the hood.

 

ENG I, ECM B, ECM I

 

Did you have power at all of this fuse with the Ignition switch in the on position?

 

Now remove the fuel pump relay In the picture below will show you what each slot is.

 

Connect the relay to battery positive and test the ground slot. Did the test light light up?

Connect the test light to ground and test the Main Power slot, Did the test light light up?

Connect the test light to ground and insert it into PCM Signal slot. Now turn the key on Does the test light light up for a few seconds then go off?

 

Once I have the answer to these test then we can contenue on.

 

graphic

 

 

 

Customer: replied 8 years ago.
OK. I don't have a test light here but do have a digital multimeter which will work just as well.
I went out and opened the block and found the fuel pump relay socket got hot and has melted. The contacts are still there and I will perform the checks later as I am due in a meeting. I will get back to you shortly. Thanks.
Expert:  Matt J replied 8 years ago.

When testing the fuel electrical system a voltmeter is not that useful. I just helped another person with the same problem. He used a voltmeter and the readings were never correct. After two days I told him to get a Test light. Once he got a test light we had the problem found on 30 minutes.

 

If the fuel pump relay socket got hot and melted then most likely you just found your problem. I have seen the fuse blocks melt before and it will require you to replace it or some can be opened up and the contacts replaced.

Customer: replied 8 years ago.
OK. I'll check it out with the test light later this afternoon.
Customer: replied 8 years ago.
OK Matt.
I got the test light. ENG I, ECM B, and ECM I all checked out OK.
I removed the fuel pump relay and check #1 says to connect the relay to the battery positive. You meant the test light to battery positive correct? I connected the test light to battery positive and the light came on when touching the Ground Slot.
I connected the test light to battery ground and the light came on when touching the Power Slot.
I turned the key on and the light came on for a few seconds when connected to the PCM slot.
So far everything checks out. Please advise.