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Shannon Martin
Shannon Martin, ASE Certified Master Technician
Category: Chevy
Satisfied Customers: 589
Experience:  over 20 years as a line technician both asian and domestic.
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1999 Chevy Blazer: 4 wheel drive, 4 door..isnt getting

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Hi, we just installed a fuel pump on a 1999 Chevy Blazer,XXXXX 4 door. Now the fuel pump isn't getting any power. Any suggestion on what we should be looking at? Thanks

Shannon Martin :

hi i am shannon i will help on this issue

Shannon Martin :

the pump gets power for three secounts when the key is first turned on

Shannon Martin :

after that it gets it power from the oil pressure switch

Shannon Martin :

but let me check that .i will get you a diagram.

Shannon Martin :

i will switch us to Q&A mode.

Shannon Martin :

and a fues loactaion

i will post back with a diagram and a fuse location .




Customer: replied 6 years ago.
It seems like we are actually not getting power initially when we turn the key.
test at the relay and let me know what you find.
Customer: replied 6 years ago.
Okay, will do right now, thanks
i,ll be hear
Customer: replied 6 years ago.

My husband is going to try testing at the relay and we'll get back to you asap. Thanks

ok thanks.
Customer: replied 6 years ago.

we're having trouble finding the relay.......can you tell me where it's at and with a description of what it looks like? Thanks!

i don,t have a diagram for it but it should be in your hand book that came with the truck. hear is what i got.







Customer: replied 6 years ago.

okay, we are double checking. I think that the relay is okay, but I will confirm that in a few minutes


first you need to be sure the relay is getting all the power and ground it need check the relay may have a diagram printed on it . the pins should be numbered 30, 87 ,86 ,85,

pin 30 should have power with key on

pin 87 is the output to the fuel pump .if you jump these two the pump should run.

86 ,85, one has power for three seconds. the other is the ground.

Customer: replied 6 years ago.
okay, I've given the info to my husband and he is checking all, will respond as soon as he gives me an update.......thank you so much for your help!
just let me know what he finds
Customer: replied 6 years ago.

The last info that you sent helped......we've located the right spot to test and are doing it now. Just so you know, my husband has done quite a bit of work on vehicles. He rebuilt the entire engine on his Ford F150 truck last year and has done lots of work on this blazer. But for some reason the replacement of the fuel pump (for the third time) has really turned into a big problem this time!


I'll have an answer for you soon.

ok good i,ll be hear all day .
Customer: replied 6 years ago.
Pin 30 has power all the time. When we jumped pin 30 to pin 87 we have power to the grey wire at the fuel pump. Pin 86 and pin 85 tested out good. The purple wire back at the fuel pump never received power during all of the tests. What should we do next.

its the gray that power the fuel pump not the purple.the purple is for the fuel level sensor,




Customer: replied 6 years ago.
he said he knows it is the gray wire that powers the fuel pump

so dose the gray wire get power when you jump the relay?down to the fuel pump? your post(The purple wire back at the fuel pump never received power during all of the tests. ( The purple wire back at the fuel pump never received power during all of the tests. What should we do next. )

Customer: replied 6 years ago.
Yes, when he does that the gray wire does get power down at the fuel pump. When we put the fuse in, it does not. We switched the fuses around to make sure that the fuses were working and when the fuse is installed, the gray wire does not get power.
so i will assume the engine runs ok when you jump the fuel pump relay.
Customer: replied 6 years ago.
Well.......they didn't try to see if it runs. They are going to do that now.
but the relay dose not close when you turn on the key. if you feel the relay close and get no power then the relay is bad .if you have power and ground at pins 86,85, and the relay dose not close .the relay is bad. you need the read 12vdc and 0.08 ohms or less at the ground before you condemn the relay.
Customer: replied 6 years ago.

trying this and checking info based on your last response......will reply again shortly

Customer: replied 6 years ago.
Well, the good news is that all of sudden the blazer is running........the bad news is that we don't know why!
you should replace the relay just to be safe. please press the ACCEPT button i will still answer on this issue. thanks shannon.
Shannon Martin and 2 other Chevy Specialists are ready to help you
Customer: replied 6 years ago.

Hi, Shannon

Are you available to answer a few more questions on this blazer? It won't start again today. Thanks

yes i can i,m back from Disneyland now go ahead and ask.
Customer: replied 6 years ago.
I'll have some questions this evening. Thanks!
ok i should be near
Customer: replied 6 years ago.
Actually, now it will probably be tomorrow or over the weekend that we may have a question or two......I think we just need to face the fact that it's time for a new vehicle!
don.t give up until we take a look i should be in and out on the weekend.