How do you put power straight to fuel pump?
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Car: 91 Z28 camaro
Engine: L98 from 90-92 camaro
Transmission: 700r4
How do you put power straight to fuel pump?
I need to know how to put power directly to my fuel pump and I cannot find this information anywhere... Basically I want to bypass the fuel pump relay, and the oil pressure switch all in one so I can rule them out of my no start condition. Oh and if there is a way to test my oil pressure switch solely then that added info would be good aswell. Thanks
Car is a 91 Z28 with a 90-92 L98 tpi.
Car is a 91 Z28 with a 90-92 L98 tpi.
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TWON_3rdGEN (03-19-2020)
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Re: How do you put power straight to fuel pump?
I cant remember which wire does what, but there's 3 wires that go into the rear bulkhead right between the rear seats. If you jack the car up you'll see above teh differential where there's an electrical fitting that is on the bulkhead and a plug going to it. One is a positive to the fuel pump, one is a ground, and one is a fuel gauge sender. I think the center wire is power, but Im not sure. Maybe find a wiring diagram? But anyway you'll see it above the axle and then it will go across and over the top of the tank. Just be sure before you start sending current into random wires up there. You're still dealing with fuel.
Last edited by InfernalVortex; 06-28-2014 at 02:54 PM.
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TWON_3rdGEN (03-29-2020)
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Car: 91 Z28 camaro
Engine: L98 from 90-92 camaro
Transmission: 700r4
Re: How do you put power straight to fuel pump?
I cant remember which wire does what, but there's 3 wires that go into the rear bulkhead right between the rear seats. If you jack the car up you'll see above teh differential where there's an electrical fitting that is on the bulkhead and a plug going to it. One is a positive to the fuel pump, one is a ground, and one is a fuel gauge sender.
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Car: 91 Firebird/88 Firebird/91 Formula
Engine: V6 3.1/V8 5.0/V8 5.0
Transmission: 4L60/700R4/4L60
Axle/Gears: 3.23/2.73/2.73
Re: How do you put power straight to fuel pump?
Okay. This coming out of my '91 service manual. There should be a test connector at the fuel pump relay on a red wire located behind the passenger side shock tower. Comes out of the relay from the "C" harness connection. You should also be able to use the direct wire from the fuel pump relay to the fuel pump at the "E" harness connection. Hope this helps a little.
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TWON_3rdGEN (03-19-2020)
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Car: 91 Z28 camaro
Engine: L98 from 90-92 camaro
Transmission: 700r4
Re: How do you put power straight to fuel pump?
Okay. This coming out of my '91 service manual. There should be a test connector at the fuel pump relay on a red wire located behind the passenger side shock tower. Comes out of the relay from the "C" harness connection. You should also be able to use the direct wire from the fuel pump relay to the fuel pump at the "E" harness connection. Hope this helps a little.
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Re: How do you put power straight to fuel pump?
I forgot about this...
There's a ALDL port that you can provide power to to power the fuel pump. It will only activate the pump if the relay is switched OFF. So key in the OFF position. This assuming you still have all the stock wiring. When the relay switches it gets power from other sources and disconnects this terminal from the circuit. So you can bypass EVERYTHING on the power side of the relay. Fuel pump draws 10 amps max.
Remember, there's a fuel pump fuse beside the battery. So check that too. I ended up blowing that fuse several times. And then I had to finally cut the wire to the OPSU because I think that's where my short was. I think my headers melted something down there just enough to cause intermittent problems.
There's a ALDL port that you can provide power to to power the fuel pump. It will only activate the pump if the relay is switched OFF. So key in the OFF position. This assuming you still have all the stock wiring. When the relay switches it gets power from other sources and disconnects this terminal from the circuit. So you can bypass EVERYTHING on the power side of the relay. Fuel pump draws 10 amps max.
Remember, there's a fuel pump fuse beside the battery. So check that too. I ended up blowing that fuse several times. And then I had to finally cut the wire to the OPSU because I think that's where my short was. I think my headers melted something down there just enough to cause intermittent problems.
Last edited by InfernalVortex; 06-28-2014 at 03:29 PM.
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TWON_3rdGEN (03-19-2020)
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Car: 91 Z28 camaro
Engine: L98 from 90-92 camaro
Transmission: 700r4
Re: How do you put power straight to fuel pump?
Yea thanks for the diagram but I looked yesterday for the ALDL and I cant find mine... You wouldn't happen to have a pic of what mine should look like would you? Thanks Infernalvortex
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Car: 91 Firebird/88 Firebird/91 Formula
Engine: V6 3.1/V8 5.0/V8 5.0
Transmission: 4L60/700R4/4L60
Axle/Gears: 3.23/2.73/2.73
Re: How do you put power straight to fuel pump?
A little more iinfo. Fuel pump relay is located at number 3. Test connector is located at "C8".
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Re: How do you put power straight to fuel pump?
Will look like this, somewhere. You dont have to remove anything to see it but it may not be visible without getting down there to find it.
This is one from an early thirdgen firebird, but my car is a 92 and it doesnt ahve this panel or the ALDL port in the same location. It's farther back and more centrally located under the steering column.
Last edited by InfernalVortex; 06-28-2014 at 03:41 PM.
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TWON_3rdGEN (03-19-2020)
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Car: 91 Z28 camaro
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Transmission: 700r4
Re: How do you put power straight to fuel pump?
Alright I think I got it. Now I just have to go out in this 90 degree heat and mess with it haha, thanks guys.
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Car: 91 Z28 camaro
Engine: L98 from 90-92 camaro
Transmission: 700r4
Re: How do you put power straight to fuel pump?
Under the dash on the driver's side.
Will look like this, somewhere. You dont have to remove anything to see it but it may not be visible without getting down there to find it.
This is one from an early thirdgen firebird, but my car is a 92 and it doesnt ahve this panel or the ALDL port in the same location. It's farther back and more centrally located under the steering column.
Will look like this, somewhere. You dont have to remove anything to see it but it may not be visible without getting down there to find it.
This is one from an early thirdgen firebird, but my car is a 92 and it doesnt ahve this panel or the ALDL port in the same location. It's farther back and more centrally located under the steering column.
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Re: How do you put power straight to fuel pump?
This is where mine is. I've got some custom wiring in there, ignore it. You see the ALDL basically above the clutch pedal.
You know which pin is what because they're all oriented exactly the same. The fuel pump port will be on the lower left.
Note if you ever need to pull codes. You put a paperclip into pins A and B and the SES light will flash codes at you once you turn the key to the "ON" position.
Last edited by InfernalVortex; 06-28-2014 at 03:47 PM.
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Car: 91 Z28 camaro
Engine: L98 from 90-92 camaro
Transmission: 700r4
Re: How do you put power straight to fuel pump?
I forgot about this...
There's a ALDL port that you can provide power to to power the fuel pump. It will only activate the pump if the relay is switched OFF. So key in the OFF position. This assuming you still have all the stock wiring. When the relay switches it gets power from other sources and disconnects this terminal from the circuit. So you can bypass EVERYTHING on the power side of the relay. Fuel pump draws 10 amps max.
Remember, there's a fuel pump fuse beside the battery. So check that too. I ended up blowing that fuse several times. And then I had to finally cut the wire to the OPSU because I think that's where my short was. I think my headers melted something down there just enough to cause intermittent problems.
There's a ALDL port that you can provide power to to power the fuel pump. It will only activate the pump if the relay is switched OFF. So key in the OFF position. This assuming you still have all the stock wiring. When the relay switches it gets power from other sources and disconnects this terminal from the circuit. So you can bypass EVERYTHING on the power side of the relay. Fuel pump draws 10 amps max.
Remember, there's a fuel pump fuse beside the battery. So check that too. I ended up blowing that fuse several times. And then I had to finally cut the wire to the OPSU because I think that's where my short was. I think my headers melted something down there just enough to cause intermittent problems.
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Car: 91 Z28 camaro
Engine: L98 from 90-92 camaro
Transmission: 700r4
Re: How do you put power straight to fuel pump?
Ok so I think my fuel pump test port is on the opposite side of your picture. It should be the solid orange wire coming from the back of the aldl that I put the 12 volts to rite? If so mine was on the bottom right side of aldl... and it did nothing and I made sure key was off.
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Re: How do you put power straight to fuel pump?
Best way to check to make sure it's oriented the same as the diagram is to do the paperclip test and find pins A and B. Should be the upper two pins on the right side. You should get the ses light flashing at you when you flip the key to the on position. It should flash code 12 at you to verify that it worked. THat's one flash, then two flashes. That will tell you where pins A and B are. I dont know what colors the wires are supposed to be, but hte ALDL should be that orientiation as the diagram above. It should not be backwards, if it is it's upside down and pin G is going to be on the opposite corner.
You can see how the circuit works in the relay here. Note the relay is on the engine bay side of the C100 connector, which can sometimes get flaky. THat's the big giant wiring harness plug on the firewall. So if you've got a problem between the relay and the pump, then this wont cause the pump to prime. You may need to pull up the carpet under the rear seat and send a positive and negative wire through two of those terminals in that plug. Or under the car, whatever you prefer.
You can see how the circuit works in the relay here. Note the relay is on the engine bay side of the C100 connector, which can sometimes get flaky. THat's the big giant wiring harness plug on the firewall. So if you've got a problem between the relay and the pump, then this wont cause the pump to prime. You may need to pull up the carpet under the rear seat and send a positive and negative wire through two of those terminals in that plug. Or under the car, whatever you prefer.
Last edited by InfernalVortex; 06-28-2014 at 09:13 PM.
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Engine: 355 w/AFR 195's Elem. 400/430 HP/TQ
Transmission: Tremec T-56
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Re: How do you put power straight to fuel pump?
A '91 does not have a fuel pump "G: ALDL connection.
antares57
listen to what he said
That wire will have a black connector on it.
Put 12v there and the pump will run.
antares57
listen to what he said
Okay. This coming out of my '91 service manual. There should be a test connector at the fuel pump relay on a red wire located behind the passenger side shock tower. Comes out of the relay from the "C" harness connection. Hope this helps a little.
Put 12v there and the pump will run.
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TWON_3rdGEN (03-19-2020)
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Re: How do you put power straight to fuel pump?
Word of caution, do not use a light up switch.
I wanted a back up bypass option to power it direct, "oh look a cool blue switch that lights up at night."
all it would do is pop the FP fuse on fender every time it was used. Use a reg toggle switch and all was well.
I wanted a back up bypass option to power it direct, "oh look a cool blue switch that lights up at night."
all it would do is pop the FP fuse on fender every time it was used. Use a reg toggle switch and all was well.
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Car: 91 Z28 camaro
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Transmission: 700r4
Re: How do you put power straight to fuel pump?
Well I honestly believe it's the fuel pump now... As of earlier I hooked 12volts power straight to the pump harness that connects above my axle, and even grounded the pumps negative side on harness, and it never came to life.
Now im not sure if this is how you test a fuel pump BUT it seems like the most reasonable way to do it, and this means it's the cause rite?
Now im not sure if this is how you test a fuel pump BUT it seems like the most reasonable way to do it, and this means it's the cause rite?
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Re: How do you put power straight to fuel pump?
Well I honestly believe it's the fuel pump now... As of earlier I hooked 12volts power straight to the pump harness that connects above my axle, and even grounded the pumps negative side on harness, and it never came to life.
Now im not sure if this is how you test a fuel pump BUT it seems like the most reasonable way to do it, and this means it's the cause rite?
Now im not sure if this is how you test a fuel pump BUT it seems like the most reasonable way to do it, and this means it's the cause rite?
Check and see if you're getting voltage at the relay and at the power wire to the pump in various places along the signal chain. Unplug the pump, obviously, you might damage your voltmeter if you don't.
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Car: 91 Z28 camaro
Engine: L98 from 90-92 camaro
Transmission: 700r4
Re: How do you put power straight to fuel pump?
Well with the key to the ON position the fuel pumps harness will only get power for the 2 second of prime up, rite?
So what I did was put direct power to where the harness disconnects on the pumps side which should run the pump no matter what.
So it's gotta be my pump or the pumps side of the harness is bad... either or.
So what I did was put direct power to where the harness disconnects on the pumps side which should run the pump no matter what.
So it's gotta be my pump or the pumps side of the harness is bad... either or.
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Car: 91 Firebird/88 Firebird/91 Formula
Engine: V6 3.1/V8 5.0/V8 5.0
Transmission: 4L60/700R4/4L60
Axle/Gears: 3.23/2.73/2.73
Re: How do you put power straight to fuel pump?
Before the last fuel pump change on my '88 I wanted the cause to be anything but the pump. But after checking relay, test port, and harness...it turned out to be the fuel pump. Point is, if you haven't changed out the fuel pump yet, it probably should be done. On both my '91 Base and '88 the strainer had disintergrated to the point that it was clogging the fuel pump. Don't forget to change out the fuel filter as well. Good luck.
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TWON_3rdGEN (03-19-2020)
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Car: 91 Z28 camaro
Engine: L98 from 90-92 camaro
Transmission: 700r4
Re: How do you put power straight to fuel pump?
Before the last fuel pump change on my '88 I wanted the cause to be anything but the pump. But after checking relay, test port, and harness...it turned out to be the fuel pump. Point is, if you haven't changed out the fuel pump yet, it probably should be done. On both my '91 Base and '88 the strainer had disintergrated to the point that it was clogging the fuel pump. Don't forget to change out the fuel filter as well. Good luck.
Because on the end of my new one it has a tag that said install new filter...
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Re: How do you put power straight to fuel pump?
There is a separate filter outside the tank... driver side, next to or just in front of the LCA.
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Car: 91 Z28 camaro
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Transmission: 700r4
Re: How do you put power straight to fuel pump?
But yea I bought a new strainer/Pump filter lol. Thanks
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Car: 86-FireBird
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Re: How do you put power straight to fuel pump?
Well I honestly believe it's the fuel pump now... As of earlier I hooked 12volts power straight to the pump harness that connects above my axle, and even grounded the pumps negative side on harness, and it never came to life.
Now im not sure if this is how you test a fuel pump BUT it seems like the most reasonable way to do it, and this means it's the cause rite?
Now im not sure if this is how you test a fuel pump BUT it seems like the most reasonable way to do it, and this means it's the cause rite?
I had a problem that that whole bulk head harness and connector and had to wire around it on mine.
Since I cut the hole for access it was easy to do that.
Oh and do not use the quick connects that come in a fuel pump kit, I made that mistake after all that work and had to go back in later. The quick connect melted and the hot wire had metled back a good 1/2 in. meaning at some point the way the FP kept working was the juice was jumping the gap.
Why it didn't go off like a bomb, I dunno.......
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Car: 91 Z28 camaro
Engine: L98 from 90-92 camaro
Transmission: 700r4
Re: How do you put power straight to fuel pump?
were you under the car doing this or in the back seat?
I had a problem that that whole bulk head harness and connector and had to wire around it on mine.
Since I cut the hole for access it was easy to do that.
Oh and do not use the quick connects that come in a fuel pump kit, I made that mistake after all that work and had to go back in later. The quick connect melted and the hot wire had metled back a good 1/2 in. meaning at some point the way the FP kept working was the juice was jumping the gap.
Why it didn't go off like a bomb, I dunno.......
I had a problem that that whole bulk head harness and connector and had to wire around it on mine.
Since I cut the hole for access it was easy to do that.
Oh and do not use the quick connects that come in a fuel pump kit, I made that mistake after all that work and had to go back in later. The quick connect melted and the hot wire had metled back a good 1/2 in. meaning at some point the way the FP kept working was the juice was jumping the gap.
Why it didn't go off like a bomb, I dunno.......
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Re: How do you put power straight to fuel pump?
youll find out, the pump is hard wired once inside the tank, so you have to cut the old one out. So they supply those cheap quick connects that you just clamp on to reconnect the wires.
they often come in tach kits too, just as bad of a use.
they often come in tach kits too, just as bad of a use.
Last edited by Gumby; 06-30-2014 at 12:13 AM.
#31
Re: How do you put power straight to fuel pump?
Okay. This coming out of my '91 service manual. There should be a test connector at the fuel pump relay on a red wire located behind the passenger side shock tower. Comes out of the relay from the "C" harness connection. You should also be able to use the direct wire from the fuel pump relay to the fuel pump at the "E" harness connection. Hope this helps a little.
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Re: How do you put power straight to fuel pump?
My cousin has a 92 Ford S10 4.3, we replaced the fuel pump and checked it and it was pumping yet when we put the bed back on the fuel pump won't come on.. Does anyone know where the fuel pump relay is on this truck. I've searched under the hood and can't find it. Please help
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Re: How do you put power straight to fuel pump?
My cousin has a 92 Ford S10 4.3, we replaced the fuel pump and checked it and it was pumping yet when we put the bed back on the fuel pump won't come on.. Does anyone know where the fuel pump relay is on this truck. I've searched under the hood and can't find it. Please help
Good Luck in your search.....
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Re: How do you put power straight to fuel pump?
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