Fuse box issues

Tiny
MEGAN DREW JACOBS
  • MEMBER
  • 2000 FORD F-150
  • 4.6L
  • V8
  • 4WD
  • AUTOMATIC
  • 160,000 MILES
We have been rebuilding this truck for months now. We put a new engine in it and replaced everything it needed to be replaced and finally got everything installed ready to go. Went to crank the truck and it turned over but wouldn't fire. So, we started checking fuses and the distribution box under the hood is only getting power to half of it in the fuse box in the dash is getting no power to anything. We still have interior lights on and still have the door ding come on we still have lights I believe but nothing else. Just this last time we tried to crank the truck it still tried to turn over like it has been doing but wouldn't start and this time it backfired. We're starting to get the smell of gas as well. We're not really sure where to go from here. The fuses that are getting power are in the Box closest to the interior of the truck. All the fuses close to the relays and the fuse for the PCM and the power control module or not working (It's a blue fuse). Please help! We have put everything into rebuilding this truck and now for it not to fire up is just heartbreaking. I mean we have dash lights I do believe but I'm not completely sure about that.
Sunday, February 20th, 2022 AT 5:51 PM

6 Replies

Tiny
STEVE W.
  • MECHANIC
  • 14,543 POSTS
What you are describing sounds like the under-hood fuse box is bad. Here are a couple things to test: You need a simple test light. Connect the light to ground, now go to the under-hood box and find fuse 103, this is a 50-amp fuse that feeds the under-dash fuse box for many circuits. Just check each side of the fuse for power, then check fuse 111 as well. They are both hot all the time so if they don't have power, you have an internal fuse box issue. If the inner fuse panel doesn't have power the truck won't run, the ECU gets power from that box.
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Sunday, February 20th, 2022 AT 10:59 PM
Tiny
MEGAN DREW JACOBS
  • MEMBER
  • 5 POSTS
Both of those fuses have power. It's half the mini fuses that don't have power according to my fiancé and I believe the relays as well have no power. And again, nothing in the interior fuse box has power.
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Monday, February 21st, 2022 AT 9:56 AM
Tiny
STEVE W.
  • MECHANIC
  • 14,543 POSTS
Okay, if those have power it has to be the wiring to the interior box from that box or the connection on the interior box. It is fed from that fuse and parts are fed through the ignition switch. The switch feeds should be okay though as it's cranking over, and you smell fuel. Both of those are fed through the switch.
Could you take a picture of the box without power? That way I can look up the actual fuse circuits that have issues. Some use common feeds while others use only feeds from other fuses.
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Monday, February 21st, 2022 AT 12:07 PM
Tiny
MEGAN DREW JACOBS
  • MEMBER
  • 5 POSTS
So, I was able to figure out what was wrong with the wiring. Two wires in the back of the bjb that Supply fuse 18 had backed out. Once I pushed them back in, I had power to the rest of the box and the fuse box in the cab.
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Tuesday, March 1st, 2022 AT 10:03 PM
Tiny
MEGAN DREW JACOBS
  • MEMBER
  • 5 POSTS
Not able to get the engine to start though. Today I replaced the knock sensor with the cylinder head temperature sensor and put the intake and wiring harness all back on making sure all connections were made and also installed all brand-new plugs. I didn't have much time to test the wiring, but I was able two chairs the spark 4 cylinder 1 and I am getting spark and also, I'm getting power to the injectors. I also know that the fuel pump is working because I can hear it priming and also one of the injectors was leaking fuel until I replaced the O-ring, so fuel is making it to the fuel rail. With spark and fuel why is it still not starting? Any suggestions?
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Tuesday, March 1st, 2022 AT 10:08 PM
Tiny
STEVE W.
  • MECHANIC
  • 14,543 POSTS
Great to hear you found the power problem. As for the engine not starting, we are supposed to answer only one issue at a time to make it easier to search for a problem. As such could you please ask that as a new question. Include the information above. In the meantime, you need fuel, air compression and timing to make them run. Check that you have spark on 1 with it on compression. Add the results of that to your new question please.
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Tuesday, March 1st, 2022 AT 10:34 PM

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