keep blowing fuel pump fuses
05-09-2006, 03:08 PM
#1
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Car: 1982 Trans Am
Engine: SBC 400
Transmission: 700-R4
Axle/Gears: 9 Bolt 2.77
keep blowing fuel pump fuses
This just started happening a few days ago...and I blew 2 fuses in one day. Can't figure this one out. Car is carbed, no computer. I have the electric pump in the tank and the wires are hooked up to the fuel pump relay like they should. I have a white line from the relay going into the fuse panel into the radio fuse...so it is hot when the ignition key is turned on. I also have a fuse before the relay. The other day I was driving and decided to get on the throttle a little. It bogged down and then I got nothing, and the car died. I pulled over and coudn't figure it out. I noticed my fuel filter was empty ( have a clear one in the engine bay) I checked the fuse going to the relay and it was blown. I replaced it, used my voltage probe and probed one of the leads on the relay. I heard it click and it triggered the pump because it filled the filter and my carbs fuel bowls. Ok...no biggie. Today the same thing happend, twice!! Except the fuese being blown this time is the fuse panel fuse, not the fuse I have before the relay. I checked the wiring as much as I could and didn't see anything unusual. I don't know what would cause the fuse to blow. It seems to only happen when I try to get on the throttle. It wants to bog and I guess the pump would be stopping since the fuses blow. Would a bad pump cause me to blow fuses??
Any help would be appreciated!
Also, since I have the relay hooked up to the radio fuse, the fuse being blown is the radio fuse...not actually the fuel pump fuse. I use the radio fuse to get power to the fuel pump relay which powers the pump. I know, probably not the best setup but that is how it was when I bought it. Also, I don't always hear the pump prime when I turn the key on. If I get power from the radio fuse it should prime it right? Sometimes I hear it and sometimes I don't.
Any help would be appreciated!
Also, since I have the relay hooked up to the radio fuse, the fuse being blown is the radio fuse...not actually the fuel pump fuse. I use the radio fuse to get power to the fuel pump relay which powers the pump. I know, probably not the best setup but that is how it was when I bought it. Also, I don't always hear the pump prime when I turn the key on. If I get power from the radio fuse it should prime it right? Sometimes I hear it and sometimes I don't.
05-09-2006, 03:43 PM
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Car: 1982 Trans Am
Engine: SBC 400
Transmission: 700-R4
Axle/Gears: 9 Bolt 2.77
yah, but that would defeat the purpose of the fuse. Then if it happens again it will probably fry the wires...that's the point of the fuse, to prevent the wires from melting. For some reason it's drawing to many amps to break the fuse.
05-10-2006, 10:43 AM
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
No, he wouldn't know what the problem was. He'd just have a burnt down car.
Obviously, the circuit is drawing more current than the fuse is rated for. Blowing the fuse at WOT only doesn't make much sense, unless there is something else drawing power through that circuit at WOT.
This isn't the factory set-up, apparently. Since it's a carb, it should have a fuel pressure regulator. Is it a return-style reg? If not, you're dead-heading the pump, which could lead to a high current load on the electrical circuit. But, that wouldn't be the worst at WOT, it would be the worst at idle.
One obvious question: Is the "radio" fuse rated at enough amperage? I'm not sure of the exact values, but the radio is typically 10 or 15 amps, and pump in the 25-30 range. The wiring has to match the fuse, of course, so you may need to use a different fuse circuit.
Obviously, the circuit is drawing more current than the fuse is rated for. Blowing the fuse at WOT only doesn't make much sense, unless there is something else drawing power through that circuit at WOT.
This isn't the factory set-up, apparently. Since it's a carb, it should have a fuel pressure regulator. Is it a return-style reg? If not, you're dead-heading the pump, which could lead to a high current load on the electrical circuit. But, that wouldn't be the worst at WOT, it would be the worst at idle.
One obvious question: Is the "radio" fuse rated at enough amperage? I'm not sure of the exact values, but the radio is typically 10 or 15 amps, and pump in the 25-30 range. The wiring has to match the fuse, of course, so you may need to use a different fuse circuit.
05-10-2006, 04:55 PM
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Car: 1982 Trans Am
Engine: SBC 400
Transmission: 700-R4
Axle/Gears: 9 Bolt 2.77
Originally Posted by five7kid
No, he wouldn't know what the problem was. He'd just have a burnt down car.
Obviously, the circuit is drawing more current than the fuse is rated for. Blowing the fuse at WOT only doesn't make much sense, unless there is something else drawing power through that circuit at WOT.
This isn't the factory set-up, apparently. Since it's a carb, it should have a fuel pressure regulator. Is it a return-style reg? If not, you're dead-heading the pump, which could lead to a high current load on the electrical circuit. But, that wouldn't be the worst at WOT, it would be the worst at idle.
One obvious question: Is the "radio" fuse rated at enough amperage? I'm not sure of the exact values, but the radio is typically 10 or 15 amps, and pump in the 25-30 range. The wiring has to match the fuse, of course, so you may need to use a different fuse circuit.
Obviously, the circuit is drawing more current than the fuse is rated for. Blowing the fuse at WOT only doesn't make much sense, unless there is something else drawing power through that circuit at WOT.
This isn't the factory set-up, apparently. Since it's a carb, it should have a fuel pressure regulator. Is it a return-style reg? If not, you're dead-heading the pump, which could lead to a high current load on the electrical circuit. But, that wouldn't be the worst at WOT, it would be the worst at idle.
One obvious question: Is the "radio" fuse rated at enough amperage? I'm not sure of the exact values, but the radio is typically 10 or 15 amps, and pump in the 25-30 range. The wiring has to match the fuse, of course, so you may need to use a different fuse circuit.
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05-10-2006, 05:04 PM
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Originally Posted by michal_larson
id say connect them and letter fry, then just replace what burned.
05-10-2006, 05:50 PM
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Originally Posted by 1982TA
It's not the factory setup...someone else hacked it up and that is what I have now. I do not have a return line coming off of the regulator...is there anyway I could be drawing fuel from the tank, lets say if the fuse blew before hand? Sort of like syponing the fuel or will this not work? Someone told me the carb could be pulling fuel from the lines even though the pump isn't working. Then if I get on it the vaccum goes down and I use up the fuel in the bowls since the pump is no longer pumping the fuel to the bowls and I'm just drawing what fuel I am getting from the vaccum at low speed or idle.
05-10-2006, 09:04 PM
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Car: 1982 Trans Am
Engine: SBC 400
Transmission: 700-R4
Axle/Gears: 9 Bolt 2.77
Originally Posted by michal_larson
man dude, you are "dead heading" your fuel pump, that would blow fuses.
05-15-2006, 05:42 PM
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
The pump could be getting tired of the abuse. As it wears/deterioates, it starts drawing more current.
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