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Old May 7, 2013 | 06:49 PM
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Fuse Size Question

I'm just wondering what the amperage is on a stock SD fuel pump or what size fuse I need to have it on. I'm running power from an added maxi fuse and need to know what size to use. Power is going from the battery --> fuse --> relay --> pump. Also there will be an OPS wired to the relay, starter solenoid, and fuel bowl heater wire if that makes any difference.
 
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Old May 7, 2013 | 07:52 PM
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Not sure about the exact amps Jacob, but Bill had me buy a 60 amp maxi for my e fuel. I'm sure he can chime in or I might have the part numbers out in the shop of the fuse/fuse housing and pigtail if you need it.
 
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Old May 7, 2013 | 08:46 PM
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Fuses are sized according to the size of the wire feeding the circuit. its meant to pop first before the wire burns. wire (and relays) is sized according to the current of the device its powering. so size the wire correctly first. its an electric motor so its going to be hefty sized wire. im thinking 12awg minimum. what size is the wire thats coming out of the motor?
 
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Old May 7, 2013 | 09:43 PM
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I used a 20 amp in line fuse to feed power to the relay>pump. If you are using the fuel bowl heater wire for the key on power to the coil side of the relay, it's already fused. The relay I used was a 60 amp relay.
 
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Old May 7, 2013 | 10:21 PM
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It's a factory relay just like the rest of them in the power distribution box. I'm not sure what size wire it is but 12 awg stands out in my memory. I guess the fuel bowl heater wire powers the key on coil through the OPS. So do I not need a fuse between the battery and relay on the 12v constant or between the relay and pump?

Also I need to find out what functions each leg of the relay provide. They are numbered and I know that tells you what is what, I just don't know waht each number means.
 
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Old May 7, 2013 | 11:16 PM
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I fused mine between the battery and relay. Look on the side of the relay and it should have a diagram of what terminals are what. I think 85 is coil positive, 86 is coil neg., 30 is 12v in and 87 or 87a, one or the other is normally open.
 
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Old May 7, 2013 | 11:59 PM
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Originally Posted by ReBilld
I used a 20 amp in line fuse to feed power to the relay>pump. If you are using the fuel bowl heater wire for the key on power to the coil side of the relay, it's already fused. The relay I used was a 60 amp relay.
I knew you'd set me straight on that...
 
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Old May 8, 2013 | 06:48 AM
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U will not want 87a its normally closed.
 
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Old May 8, 2013 | 10:50 AM
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Originally Posted by ReBilld
I fused mine between the battery and relay. Look on the side of the relay and it should have a diagram of what terminals are what. I think 85 is coil positive, 86 is coil neg., 30 is 12v in and 87 or 87a, one or the other is normally open.
Originally Posted by fordman67
U will not want 87a its normally closed.
So based off of this info I think I need the battery running to 30, fuel bowl heater wire to 85 via the OPS, 86 to a ground, and 87 to the pump? And leave 87a alone.
 
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Old May 8, 2013 | 11:53 AM
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Question

What OPS stand for?

 
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Old May 8, 2013 | 01:18 PM
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Originally Posted by RÖENTGEEP
What OPS stand for?

Oil Pressure Switch
 
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Old May 8, 2013 | 01:41 PM
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Smile

Originally Posted by redman84
Oil Pressure Switch
Ah, OK, thanks Jacob

 
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Old May 8, 2013 | 02:50 PM
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The fuse in Todd's truck is a 20A as well. It was that or a 10A since those were the only two I had on hand at the time we wired up his E-Fuel. In fact his is a glass fuse... Gotta use what you have available. It wouldn't have been my first choice, but it works.
 
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Old May 8, 2013 | 03:11 PM
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Originally Posted by redman84
So based off of this info I think I need the battery running to 30, fuel bowl heater wire to 85 via the OPS, 86 to a ground, and 87 to the pump? And leave 87a alone.
Yep ........
 
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Old May 8, 2013 | 03:35 PM
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Originally Posted by DIYMechanic
The fuse in Todd's truck is a 20A as well. It was that or a 10A since those were the only two I had on hand at the time we wired up his E-Fuel. In fact his is a glass fuse... Gotta use what you have available. It wouldn't have been my first choice, but it works.
Like I was telling Bill, that's the one draw back to having everyone help on my truck. Some things I have no idea are in there now! Lol. However, I'll take that over not having e fuel and a broken trans...
 
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