Low voltage at fuel pump fuse

Edfol15

New Member
Jul 19, 2019
3
0
1
26
Maryland
So I just inherited my dads 1995 3.8L V6 mustang that’s been sitting for 5 years and I’m having a power supply issue to the fuel pump. I know the pump is good because I jumped the power supply to it and it turns on so I checked voltage at the fuse box and it’s only showing 6.5 volts and it should be 12volts I’m looking for help in chasing down this electrical issue that occurring somewhere between the battery and the fuse box and the battery is good it’s showing 11.79 volts there is also a spark issue so I’m wondering if there’s a component that might control these 2 issues I’m having new to ford motors usually work on Chevy and Nissan so any help would be greatly appreciated
 
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wmburns

SN Certified Technician
Aug 14, 2009
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499
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Houston Texas
Most of the fuses in the battery junction box (BJB) are "always on". In this case when the fuse is removed there are two prongs. A supply side and a "load" side.

IF you are saying that there is excessive voltage drop on the supply side, THEN the problem HAS to be inside the BJB. A visual inspection is your friend.

Here's some more information on voltage drop testing.

Howto perform charging system voltage drop test
 

Edfol15

New Member
Jul 19, 2019
3
0
1
26
Maryland
Most of the fuses in the battery junction box (BJB) are "always on". In this case when the fuse is removed there are two prongs. A supply side and a "load" side.

IF you are saying that there is excessive voltage drop on the supply side, THEN the problem HAS to be inside the BJB. A visual inspection is your friend.

Here's some more information on voltage drop testing.

Howto perform charging system voltage drop test
Will a bad ccrm cause low voltage at the fuse pump
 

Edfol15

New Member
Jul 19, 2019
3
0
1
26
Maryland
Most of the fuses in the battery junction box (BJB) are "always on". In this case when the fuse is removed there are two prongs. A supply side and a "load" side.

IF you are saying that there is excessive voltage drop on the supply side, THEN the problem HAS to be inside the BJB. A visual inspection is your friend.

Here's some more information on voltage drop testing.

Howto perform charging system voltage drop test
And no spark at the plugs
 

wmburns

SN Certified Technician
Aug 14, 2009
5,807
499
164
Houston Texas
Will a bad ccrm cause low voltage at the fuse pump
well..........yes. But if the supply to the CCRM is low is it a surprise that the output is also low? After all the CCRM is basically just a relay.
And no spark at the plugs
Why go looking to replace parts before some of the most basic electrical items have been ruled in/out? Don't make this harder than it really needs to be. A few very short voltage tests will confirm one way or the other IF there's a problem in the BJB. It only takes a few seconds to measure the voltage at the BJB fuses. After all each of the fuses have a convenient metal probe right on the top put there for just such a purpose.

Or just "parts change" the CCRM. If it's where the problem is, then you made the right call (back slap).
 
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