No Power to Pump??
10-05-2012, 11:39 PM
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No Power to Pump??
Helping a buddy on a 02 silverado was driving it the other day and thought the fuel pump went out. Put the new pump in a bam no power to it at all, although if we jump the relay it'll work just not off the computer. so far we've tried another relay, checked the ecmb fuses, the fuel pump grounds good, another pcm and even trying to command the pump to come on from hptuners does no good. is there a ground from the pcm im missing here its running me crazy!!! HELP!
10-06-2012, 08:11 AM
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Get a meter and verify that you are getting a signal from the terminal 86 when key is applied. if not then check from there. I know sometimes on some other vehicles, you also need to verify all other fuses i.e. hazards, turns etc. I have seen dumb crap like those fuses blown and the fuel pump not work
10-06-2012, 08:15 AM
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ive checked all fuses. it was getting power to one post on the relay i forgot which one but i could jump town of them and the pump would work, 87 and 30 are the ones i jumped.
10-07-2012, 07:43 AM
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87 is the lead that goes to the pump
30 is the lead that goes to 12v power.
So yes it will work by jumping it that way.
You need to check to see if you have power on 86 lead as that is your ignition source. 85 is ground lead off relay. Verify that when you turn key on at 86 lead that it works. Hell, trying jumping it via that one also. If no power when key is on at terminal 86 then you need to follow the system back and keep checking until you find the issue. I know in the blazer a lot of crap goes back to the ignition switch and we have replaced that wiring harness several times for dumb crap that you list
30 is the lead that goes to 12v power.
So yes it will work by jumping it that way.
You need to check to see if you have power on 86 lead as that is your ignition source. 85 is ground lead off relay. Verify that when you turn key on at 86 lead that it works. Hell, trying jumping it via that one also. If no power when key is on at terminal 86 then you need to follow the system back and keep checking until you find the issue. I know in the blazer a lot of crap goes back to the ignition switch and we have replaced that wiring harness several times for dumb crap that you list
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10-18-2012, 04:22 PM
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Actually it sounded like a ground issue??
Check Resistance to ground from Pin 85
check for 12v on pin 86 key off and on..
its only gonna be on for about 2 seconds after the key is on so need two people or long leads on a meter.
Check Resistance to ground from Pin 85
check for 12v on pin 86 key off and on..
its only gonna be on for about 2 seconds after the key is on so need two people or long leads on a meter.
10-30-2012, 07:58 AM
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we're still messing with it and so far pin 87 is a ground when the pump is plugged up and soon as its unplugged its not a ground anymore. Not sure at all
10-30-2012, 09:38 AM
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87 should be the out goin power to the pump.. your seeing resistance thru the fuel pump magnets to ground..
when you unplug the pump your breaking continunity.
plug the fuel pump in, Pull the relay out.. jump 30 and 87.. even with the key off you should have power to the pump.
when you unplug the pump your breaking continunity.
plug the fuel pump in, Pull the relay out.. jump 30 and 87.. even with the key off you should have power to the pump.
Last edited by nonnieselman; 10-30-2012 at 09:44 AM.