HELP! 97 fuel pump wire harness issues

[jennylove21326]

I REALLY NEED HELP!!!

I have been trying to figure this one out for some time now.. I have a 97 with a rectangle fuel pump wire harness connector. THe issue I am having is my husband threw away the old connector before installing the new one which has 4 WHITE wires!!!! If anyone could help me out as to which color wires plug into with alphabetical spots on the harness. I have white wires going into a, c, e, and f.........


He is working 7 days a week and I am tired of hoping he will find some time and energy to do this... I am not afraid to do the work myself, in fact probably should have in the first place.

 

[jennylove21326]

Ok, so with no help, I mananged to get the wired properly run, but have no power to pump, relays are fine, so ANGRY with this truck right now I wish I had full coverage so I could set it ablaze and get a replacement vehicle!!!!!! i REALLY NEED SOME DESCRIPTIVE IDEAS.

 

[SunlitComet]

if you are absolutely sure you have it wired correctly check for resistance on the connector ground circuit for the pump to the left frame rail where the wire ground to. and you do know that when you turn on the key that relay will only be powered for 2 seconds right?

 

[jennylove21326]

Thanks for the reply. I am sure that it is wired correctly. I double checked the wiring by straightwiring and pump kicked right on... Then I cheched the wires on the truck and have no power coming from the front of the truck..... GRRRR.... Stupid truck. So, after some research, I found that the wiring to the fuel pump goes thru the oil pressure switch?? Why, I am not sure, but I am thinking maybe when I can actually find that thing, I will check the connector there and possibly replace both the connector and the switch to play on the safe side.. Both are 50 at autozone, so that's not bad. Do you think, that it is possible, because my old connector was fried at the fuel pump, (which blackened my fuel pump pretty good too!) that maybe the other end (at the oil pressure switch) could have fried too?? Or any other options at this point....

---------- Post added at 12:35 PM ---------- Previous post was at 12:32 PM ----------

Oh and helpful info.....

Tank is still on ground beside truck until I have the electrical figured out!!

No point in putting it back in when having it out gives me more room to work on the wires... Especially since I fear there may be a re-wire in my near future! LOL

 

[SunlitComet]

on the 97 model the pcm powers the relay for priming, starting. afterwards oil pressure in the pressure switch maintains the power. the purpose is to ensure that during a roll over or sudden stoppage of oil pressure the fuel supply is cut of to prevent a run-on or engine damage. the relay output and oil pressure switch output meeting a splice about 16 cm from the fuse relay block.you need to find out why the relay will not activate when turning the key on for 2 seconds. solve that, and assuming all other wiring and components are good, and once started the oil pressure will keep the pump running. Below is a diagram of the setup. you could try testing the relay or shorting its connector block to see if pump runs thru the original wiring.

 

[jennylove21326]

Ok. So I am still working on this. We have been checking wires and have determined that there is no power going into the relay for the fuel pump. I have looked at the diagram shared in the previous reply. (Thank you Sunlit Comet!) I am trying to to figure this one out. If we run power from 12V to pump we get a running pump. If we splice and run power to gray at oil pressure switch (after the connector going back to relay) we get nothing. Power to fuel pump prime connector and it works. I am not a genius when it comes to reading these wiring diagrams, but I do get the jist of what is going where and how to read the flow of power. All I can see going into the relay, power wise, is Orange from the Power Distribution cell, and gray from the Oil pressure switch. We are replacing the Oil pressure switch in the AM just in case it has failed,and the wiring connector that plugs into it looks good, No corrosion or blackening. So we aren't replacing that just yet.

 

[SunlitComet]

the oil pressure switch will not provide power till engine is running a few seconds. Are you saying there is no power available at anytime at terminal 87 of relay as if it was sitting in its socket?

 

[melissa0703]

Tahoe pigtail

@jennylove21326.. we are having the same situation please help us out our pump won't even kick in..how did you connect them..

 

[SunlitComet]

@jennylove21326.. we are having the same situation please help us out our pump won't even kick in..how did you connect them..

year and engine info please.

 

[inthechateau]

Really sounds like they have a bad ground to the pump.

 

[dodgechick82]

the old wiring is the 1st pic 2nd is what new harness looks like how do i wire this up ? when i match colors pump comes on but when i set it up trying to follow diagram on paper fuel gauge on dash jumps all the way passed full and pump does not come on my brain is tired changed crank sensor n fuel relay fuse n this is new pump spectra premium sp415m model

 

[dodgechick82]

and also first pic is a,c,e,f order not what it shows on paper for diagram?

 

[east302]

No idea if it will help, but here’s a video on it. Maybe you’ll spot something of use.

 

[Fless]

the old wiring is the 1st pic 2nd is what new harness looks like how do i wire this up ? when i match colors pump comes on but when i set it up trying to follow diagram on paper fuel gauge on dash jumps all the way passed full and pump does not come on my brain is tired changed crank sensor n fuel relay fuse n this is new pump spectra premium sp415m model

Can you show us a pic of the front of this connector? What make/model/year did it come off of?

 

[dodgechick82]

came off 97 tahoe 4 dr vortec can show after when u go out the truck to wire it up again was hoping for a good response

 

[dodgechick82]

No idea if it will help, but here’s a video on it. Maybe you’ll spot something of use.

yes i watched this thank u when i follow diagram on paper my pump does not come on but my fuel gauge works and isnt all the way passed full on dash but when i match color for color the pump works comes on n fuel sprays out up front under the hood

 

[dodgechick82]

I REALLY NEED HELP!!!

I have been trying to figure this one out for some time now.. I have a 97 with a rectangle fuel pump wire harness connector. THe issue I am having is my husband threw away the old connector before installing the new one which has 4 WHITE wires!!!! If anyone could help me out as to which color wires plug into with alphabetical spots on the harness. I have white wires going into a, c, e, and f.........


He is working 7 days a week and I am tired of hoping he will find some time and energy to do this... I am not afraid to do the work myself, in fact probably should have in the first place.

i have similar situation but my wires are not all white same order old connector a,c,e,f but on new fuel pump diagram they send with it shows different n my wires r 2 blacks but one is solid n other is black/brown n grey and purple

 

[exp500]

4 wires, 2 for gas gauge,2 for fuel pump. Usually fuel pump are larger diameter. Find the Ground spot near gas tank, that should be or connect to fuel pump ground ( to help with which terminal on pump is ground).if small dia white wire,usually signal to gas gauge/ecm. Careful about black with white stripe.
Wiring diagrams are here-

Helpful Links

Helpful links- If this is a successful post maybe it could be stickied! Here's the first- https://www.gmt400.com/threads/88-95-service-manuals.43575/ https://67-72chevytrucks.com/vboard/showthread.php?t=700011

www.tahoeyukonforum.com

 

[Fless]

@dodgechick82 started a new thread:

1997 tahoe 4x4 4door vortec crank no start after installing new pump

i have checked ground straps they r good replaced crankshaft sensor n fuel relay fuse when i connect wiring to new harness matching colors pump comes on n fuel sprays out the front under the hood and fuel gauge goes passed full on dash but there is not a full tank if gas and when i follow...

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