Need help! Fuel system! AGAIN!
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Senior User
Joined: Oct 2010
Posts: 185
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From: Corpus Christi, Texas
Need help! Fuel system! AGAIN!
Ok I have posted this about twice. But I didn't want to bump the old posts because I have new updates. My front pump works, but not my rear pump.
Ok as in the previous posts, I have replaced these:
1 New Motorcraft Fuel Pump
3 BWD Fuel Relays
1 20 AMP Maxi Fuse
1 Selector Switch in the Dash
And nothing!
But then about 3 or 4 days ago I got pissed and hit (not to hard) the Power Distribution Box (where the Fuel Relay is) and VIOLA! The rear pump turned on! Yay!!
But wait, one day after using the rear tank I noticed a leak coming from the top of the tank (not gushing, just a slow leak), where the fuel pump and lines are, so I just switched to the front tank an drove home and inspected the leak. It turned out when I had put the "seal ring" it had not tightened correctly, so I reinstalled the ring and put Seal All just in case.
And guess what?! Just from that little disturbance, the fuel pump now gets no power. How could this be?! I tried hitting the PDB again as before it had worked and nothing. Still dead.
I'm at a loss! Please if anyone can help, I would greatly appreciate it!
Ok as in the previous posts, I have replaced these:
1 New Motorcraft Fuel Pump
3 BWD Fuel Relays
1 20 AMP Maxi Fuse
1 Selector Switch in the Dash
And nothing!
But then about 3 or 4 days ago I got pissed and hit (not to hard) the Power Distribution Box (where the Fuel Relay is) and VIOLA! The rear pump turned on! Yay!!
But wait, one day after using the rear tank I noticed a leak coming from the top of the tank (not gushing, just a slow leak), where the fuel pump and lines are, so I just switched to the front tank an drove home and inspected the leak. It turned out when I had put the "seal ring" it had not tightened correctly, so I reinstalled the ring and put Seal All just in case.
And guess what?! Just from that little disturbance, the fuel pump now gets no power. How could this be?! I tried hitting the PDB again as before it had worked and nothing. Still dead.
I'm at a loss! Please if anyone can help, I would greatly appreciate it!
Posting Guru
Joined: Dec 2009
Posts: 1,053
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From: Calverton
There's no magic answer on this one, you have to trace the power from the PCM to the pump. You need a repair manual with a wiring diagram, a test light would help, as would a multimeter. If you don't have a manual, the local library might, I've done that plenty. You need a short jumper wire as well to go from 2 to 6 on the test plug, so that your pump circuit should be energized during testing, and a straight pin to check some wires by piercing the coating jacket. Really not a lot of time to find the culprit, just a hassle...be real careful not to ground out anything
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
If one of the tank works then the fuel relays and the PDB is OK.
Your problem is between the selector switch an the pump in the tank.
You need to short Pin#2 to pin #6 of the self-test plug, select the rear tank and turn on the key.
Take a test light (not a meter) and check for power at the plug coming off the frame that plugs into the rear fuel tank pigtail.
Use the ground wire in the plug for ground and not the frame.
If you have power at the plug then the problem is a bad fuel pump, take it back and get another one.
If no power see if you have power at the safety wall plug and then the selector switch for the rear tank.
/
Your problem is between the selector switch an the pump in the tank.
You need to short Pin#2 to pin #6 of the self-test plug, select the rear tank and turn on the key.
Take a test light (not a meter) and check for power at the plug coming off the frame that plugs into the rear fuel tank pigtail.
Use the ground wire in the plug for ground and not the frame.
If you have power at the plug then the problem is a bad fuel pump, take it back and get another one.
If no power see if you have power at the safety wall plug and then the selector switch for the rear tank.
/
Thread Starter
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Senior User
Joined: Oct 2010
Posts: 185
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From: Corpus Christi, Texas
Ok Bill, I understand the diagram mostly. Also at the bottom of the diagram where it looks like there are examples of the fuel relay, am I correct? Just wondering.
Oh and I've tried searching for the C205 plug and I'm guessing it is in the engine compartment on the fire wall going to the PDB or is it inside the cab? I'll snap a picture to see which plug is C205.
Also Ford Slip Man, does it really matter what kind of wire I use to jump pin #2 and pin #6?
Thank you both.
Oh and I've tried searching for the C205 plug and I'm guessing it is in the engine compartment on the fire wall going to the PDB or is it inside the cab? I'll snap a picture to see which plug is C205.
Also Ford Slip Man, does it really matter what kind of wire I use to jump pin #2 and pin #6?
Thank you both.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
C205 is the plug closest to the center with a bolt in it.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
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Thread Starter
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Senior User
Joined: Oct 2010
Posts: 185
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From: Corpus Christi, Texas
Take a test light (not a meter) and check for power at the plug coming off the frame that plugs into the rear fuel tank pigtail.
Use the ground wire in the plug for ground and not the frame.
If you have power at the plug then the problem is a bad fuel pump, take it back and get another one.
Use the ground wire in the plug for ground and not the frame.
If you have power at the plug then the problem is a bad fuel pump, take it back and get another one.
Or is the C205 the "safety wall plug"?
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Thread Starter
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Senior User
Joined: Oct 2010
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From: Corpus Christi, Texas
Oh shoot, nevermind! I forgot about the plug right next to the fuel pump! That is the one you're talking about in the first quote right?
And the C205 is the "safety wall plug" in the second quote.
Gotcha. I'll got check it all right now.
And the C205 is the "safety wall plug" in the second quote.
Gotcha. I'll got check it all right now.
Thread Starter
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Senior User
Joined: Oct 2010
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From: Corpus Christi, Texas
Well I'll be damned! I guess whenever I took the bed off and fixed the ring, whenever I reinstalled the bed it must have made the plug right on the fuel pump unplug, so I just climbed under the truck and simply plugged it back in! Wow, I guess next time I'll pay attention.
But nevertheless, thank you Bill, and Slip for the ideas in case anything else comes up! Oh and get this the fuel gauge now works when I switch it to the rear tank.
Now to fix the front... But that'll be in a different thread whenever I get the money and time to do it.
Once again, thanks yall!
But nevertheless, thank you Bill, and Slip for the ideas in case anything else comes up! Oh and get this the fuel gauge now works when I switch it to the rear tank.
Now to fix the front... But that'll be in a different thread whenever I get the money and time to do it.
Once again, thanks yall!
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