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Old 07-24-2018, 12:35 PM   #1
69BUCKET
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Fuel pump quit...help

5.3/th350 in a '69....put little over 100 miles on it with no issues and love the way it ran.

Went to start it to show my brother, fired right up, as usual....then just shut down. Tried to fire it up, but pump didn't buzz to prime system like usual. In line fuse for pump is good, 4 30a fuses for system are good. What i did notice was one relay isn't getting switch on power. I jumped power to the switch on power for that relay hoping it was bad, but no buzzing from fuel pump. Tried a new relay, still no switch on power.

Any ideas on what to try next? The relay does have constant power...but no switch power. Even when jumped, no buzzing from pump. Need some help.
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Old 07-24-2018, 12:41 PM   #2
BR3W CITY
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Re: Fuel pump quit...help

If its not getting switched power, then you need to backtrack the switched source your using and see where the power isn't flowing. What are you using to trigger the relay? ignition on, the ecm command, an external switch?
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Old 07-24-2018, 12:49 PM   #3
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Re: Fuel pump quit...help

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Originally Posted by br3w city View Post
if its not getting switched power, then you need to backtrack the switched source your using and see where the power isn't flowing. What are you using to trigger the relay? Ignition on, the ecm command, an external switch?
it was a 4-wire harness and wired it with ignition on...
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Old 07-24-2018, 12:53 PM   #4
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Re: Fuel pump quit...help

I figured when switch is on and didn't fire pump, i would jump power to it to see if it would fire...but nothing. So even if i get power to the relay, nothing is happening.
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Old 07-24-2018, 02:24 PM   #5
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Re: Fuel pump quit...help

Can you tell if the relay "clicks" could it be bad? I see you have replaced it. What about the ground? The relay and pump needs to be grounded good. and check your other grounds too. They can be a bit finicky.
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Old 07-24-2018, 02:50 PM   #6
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Re: Fuel pump quit...help

Checked grounds...block, firewall, battery, rad.support, fuel pump, all good....next?...
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Old 07-24-2018, 03:08 PM   #7
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Re: Fuel pump quit...help

Put hot 12 to the pump and throw a meter on it to see what it draws. If its making no noise but drawing amps, then its seized
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Old 07-24-2018, 04:11 PM   #8
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Re: Fuel pump quit...help

On it....
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Old 07-24-2018, 05:17 PM   #9
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Re: Fuel pump quit...help

Pump is spinning as it should when 12v is applied....now what?....
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Old 07-24-2018, 05:24 PM   #10
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Re: Fuel pump quit...help

Wiring for pump does as it should...12v for couple seconds...then goes down...
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Old 07-24-2018, 07:26 PM   #11
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Re: Fuel pump quit...help

Figures...wire connections at the pump...��....the orginal nuts it came with didn't fit and the connection i came up with was loose....long day for a silly mistake...carry on...nothing to see here....
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Old 07-24-2018, 08:22 PM   #12
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Re: Fuel pump quit...help

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Originally Posted by 69BUCKET View Post
Figures...wire connections at the pump...��....the orginal nuts it came with didn't fit and the connection i came up with was loose....long day for a silly mistake...carry on...nothing to see here....
It happens to the best of us. I know I’ve had plenty of these things happen to me. At least you figured it out.
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