Fuel pump wiring

Tiny
T.HART
  • MEMBER
  • 1995 CHEVROLET BLAZER
  • 4.3L
  • V12
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
My fuel pump went out on my vehicle listed above. I went and purchased a new fuel pump. I dropped the tank, replaced fuel pump, but fuel pump is a little smaller than the housing it sits in. So I went to the scrap metal yard, and there was a newer model Blazer. I took the tank off it. I need to know the wire diagram (which wire goes from the old to new model) It is a 4 connect (just like the one in the video I was watching where you did the full tutorial on how to change the fuel pump and how to put on the new wire harness.
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Thursday, November 19th, 2020 AT 10:57 AM

8 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Do you know what year the Blazer was that the fuel pump came out of? If I am reading this correctly, the current one on your vehicle has 2 wires. Is that correct? Take a look at the wiring diagram and then if you get me the year the new pump is out of I can get the diagram for that one.
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Thursday, November 19th, 2020 AT 3:21 PM
Tiny
T.HART
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I will get a picture of it tomorrow for you, so I can show you what I am talking about. But the current one one my 1995 Blazer has 3 wires on a connect that connects to the fuel tank. I believe the new tank which has 4 wires is off a 2000. All the wires match, but one since mine has 3, and that is the black and white wire. I don't know what it does or what to do with extra wire.

The whole reason I am replacing the fuel pump is because the one day I had went to the store. When I got out of the store and went to go crank my
blazer wouldn't start. I didn't hear the fuel pump, I banged on it several times, still wouldn't start. Got it towed home. I got the new fuel pump (which it's smaller than the one that was originally on there, and I had problems keeping it in the housing it goes on, so I bent the bottom of plate where fuel pump goes). To make the long story short, I connected everything, put the tank up, and still won't start.
I have dropped the tank several times, but nothing. That's when I decided to get the other tank.

I hope you can understand what I am saying.
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Thursday, November 19th, 2020 AT 4:13 PM
Tiny
KASEKENNY
  • MECHANIC
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Okay. The pictures will help but I think the difference is the newer vehicle has a combination pump and fuel level sensor. So the older pump is more then likely just a single wire sensor and the new has a 2 wire sensor.

Let's get the pictures and go from there. Thanks
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Thursday, November 19th, 2020 AT 6:47 PM
Tiny
T.HART
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  • 4 POSTS
I will get a clear picture of old one that was on my blazer, but it has 3 wires on the connect that connects to the fuel pump. I believe it is a 2000 model that I took the tank off of. I was looking at them, and 3 of the 4 wires match, but the 4th one on new tank there is a black and white wire, I don't know what that goes to, or what it does?
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Friday, November 20th, 2020 AT 7:51 AM
Tiny
T.HART
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  • 4 POSTS
I'm just lost, and thinking of many ways. Would the new tank work on old Blazer, since new tank has two parts you connect it on top of tank? Or I wouldn't have to worry about that, just the one part that we are still discussing?
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Friday, November 20th, 2020 AT 8:20 AM
Tiny
KASEKENNY
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The tanks are slightly different so I am not sure that they will fit. Maybe I didn't understand that at the beginning. I thought you were taking the pump out of the new tank and putting it in the old tank. If you are planning on using the entire new tank, I would try to fit it in place just to see if it will fit. If it doesn't then the wiring won't matter if you can't use it.

However, if the new pump fits in the old tank, I would just go that route if it doesn't fit. At that point, we can't worry about wiring colors matching up. We need to make sure what each wire does goes to the same wire on the new pump. Meaning the power wire on the harness needs to go to the power wire on the new pump. The color of the wire may not be the same. This is why seeing both connectors will help. I show on the new pump you have 4 wires. The pictures are needed because I think you said the old pump has 3 wires, the new pump has 4. I just want to see them so that I can match up the wires to the wiring diagram so that I know what each one of those wires does. Then we can match them together once we know what each one does.
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Saturday, November 21st, 2020 AT 7:08 AM
Tiny
T.HART
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Okay, yes that all makes sense. I will get the pictures to you ASAP. I'm not going to put new tank on Blazer.
When you do match up each color wire and identify what it is. Can you tell me which is which? I understand the diagrams a little but you telling me, I have a better understanding.
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Saturday, November 21st, 2020 AT 8:44 AM
Tiny
KASEKENNY
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Yes. I will tell you what wire does what. Meaning the power feed wire, ground, fuel level signal, etc. I just need to see each one and then we can start figuring this out. Thanks
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Sunday, November 22nd, 2020 AT 3:22 PM

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