silly question but which of these fuses "might" belong to the fuel pump

jcolman

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I want to do a compression test on my engine but I need to disable the electric fuel pump first. Without removing the fuses one at a time, does anyone have an idea of which of these might go to the fuel pump? I know, it shouldn't take me more than five minutes to find the right one, but I don't want to risk breaking one by taking it out and putting it back in. Thanks!

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jcolman

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You're kidding, right? :poke:
Actually not. I'm 72 years old and it's hard for me to scoot down under the dash, pull a fuse, climb back up, turn on the ignition listening for the fuel pump, then, when it's the wrong fuse, climb under the dash again. Rinse and repeat. I just hoped that someone might be able to steer me to the right fuse from the start. But if no-one knows the answer, then I'll start pulling fuses one at a time and hope my back holds up.
 

Dana67Dart

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There is no way for anyone to know...

1. If the electric fuel pump is even fused.
2. If it is running off the cars electrical system, or directly from the battery or the alternator.
3. If it is switched by a relay.



That being said...


1. it should be controlled by a switched wire from IGN 1 and / or IGN 2
2. It probably draws a bunch of amps so minimum a 20 amp cir.



The only way to find out...


Start at the fuel pump and trace the wire back to the battery.

That's the only way to know.

You could always disconnect and plug the outlet from the pump to the carb / EFI
 
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jcolman

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Start at the fuel pump and trace the wire back to the battery.

That's the only way to know.

You could always disconnect and plug the outlet from the pump to the carb / EFI
Thanks for the info. There's no easy way to trace the fuel pump wire from the tank to the battery as it's all bundled, wrapped and tied with a lot of other wires. I'm running a Holley Sniper so unplugging the harness should do the trick. I should have thought of that first.

Edit: I looked on Holley's website and found the wiring diagram. The "blue" wire connects to the fuel pump. I was able to trace it to where it comes out of the harness, and plugs into the system. It was a simple matter to unplug it. Thanks again for your suggestion! I feel like an idiot for not thinking along these lines!
 
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mopowers

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Actually not. I'm 72 years old and it's hard for me to scoot down under the dash, pull a fuse, climb back up, turn on the ignition listening for the fuel pump, then, when it's the wrong fuse, climb under the dash again. Rinse and repeat. I just hoped that someone might be able to steer me to the right fuse from the start. But if no-one knows the answer, then I'll start pulling fuses one at a time and hope my back holds up.

I didn't mean to be a dick - I was just havin fun with you. But honestly, like Dana67Dart pointed out, how in the world were any of us to know based on that photo you posted? No one here has a crystal ball. Glad you were able to figure it out. When all else fails, disconnecting the power (or ground) is a foolproof way to disable the device. :thumbsup:
 

12many

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If you can source one at a local parts store, a remote starter trigger is a worthwhile investment, not that costly. Sooo convenient for various things other than compression testing. It’s the perfect answer to your situation. Work smarter, not harder. Save The Back! :thumbsup:
 

jcolman

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I didn't mean to be a dick - I was just havin fun with you. But honestly, like Dana67Dart pointed out, how in the world were any of us to know based on that photo you posted? No one here has a crystal ball. Glad you were able to figure it out. When all else fails, disconnecting the power (or ground) is a foolproof way to disable the device. :thumbsup:
No worries. I know that I'm not much of a mechanic when it comes to cars so I had no idea that a fuel pump could be wired up in so many different ways. I'm glad I was able to figure it out with the help from all you guys! My plan for reading the compression numbers (since I'm doing this all by myself) is to shoot a video of the guage with my phone while I crank the motor. I'lll able each "take" with the cylinder number. Buying a remote starter is probably a good idea if I was going to keep working on this car, but I have it up for sale and this will be my last classic muscle car.
 

Dfr360cuda

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Fuse 1 and 6 are marked 5 amp.
Fuse 6 looks like all the other fuses marked 20 amp.
How much current does the fuel pump draw.
I would start at Fuse #6
 
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