Rear tank help
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
Just got the old tank out. Before I completely dropped it I disconnected the fuel lines and tried to activate the pump and it didn't cycle. I assume each pump has it's own relay and the previous owner may have removed it. Which relay should I check and is there something else I should look for, like a fuse maybe?
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
Then I'm hoping it's just a bad pump since the front pump works fine. Didn't get done today, but got everything connected and new tank in place. Had a lot of trouble getting the short rubber hose that connects the tank to the filler neck installed, primarily tightening the band clamp at the tank. I'm thinking maybe I should have installed it before placing the tank, but it didn't look like there was enough room for that. I did have to cut the factory harness and wire in the one supplied with the tank, but the instructions were clear and I'm sure I did it right. It came with heat shrink connecters and I sealed it good. Also replace all rubber hosed with new fuel rated hose. I'll finish in the morning and report back. Also had to remove the damn hitch.
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
It was quite the adventure, but got er done. Thought I had it and went to the gas station and put 3 gallons in, started the truck, switched to the rear tank and truck stumbled and shut off. Switched back to the front and truck wouldn't start. Finally found a blown fuse replaced it and truck started. Also noticed I was leaking gas above the tank. Made it home leaking gas the whole way. Realized gas still gets sent to the rear tank line even when just using the front tank and lowered the tank and determined the supply line was not connected properly. Reconnected it and tested with no leaks. Checked the wiring again and discovered I had the pump ground and sender ground reversed. Switched them and everything is good. Haleigh damn loughya!
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
Well, I spoke too soon. I've primed rear pump multiple times and I can hear it run, but truck seems to run out of gas when I switch to the rear. If truck is running on the front tank and I switch to rear it starts to stumble and then dies. The sender is working as it should. I have about 8 gallons of gas in the tank, didn't want to put any more than that in it in case I have to drop it again. I'm really hoping that's not the case. I could really use some help here.
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
Have not. I'll need to buy a gauge that connects to the shrader I guess. I hate thought of the new pump being bad.
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
I rented a fuel pressure test gauge today and I have no pressure at the rail when switched to the rear tank. I cycled the pump about 10 times and nothing. Could it be a bad switch not sending a full 12 volts to the pump? If not, it seems to me the new pump has to be bad. Am I missing something?
Laughing Gas
Joined: Apr 2011
Posts: 913
Likes: 7
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
This is how I have it wired:
----------------------------------New Harness------------------------- Vehicle Harness
Pump Power--------------------- Gray---------------------------------- Orange
Pump Grnd---------------------- Black--------------------------------- Black/White
Sender Pwr--------------------- Purple-------------------------------- Yellow/White
Sender Grnd------------------- Black/White---------------------------- Black
The new harness colors and identifications are from the install directions.
----------------------------------New Harness------------------------- Vehicle Harness
Pump Power--------------------- Gray---------------------------------- Orange
Pump Grnd---------------------- Black--------------------------------- Black/White
Sender Pwr--------------------- Purple-------------------------------- Yellow/White
Sender Grnd------------------- Black/White---------------------------- Black
The new harness colors and identifications are from the install directions.
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
I feel like I have the wiring correct, the pump does cycle and the fuel gauge works. As shown above, the factory wiring coming to the pump are Orange, Black, Black/White and Yellow/White
Lead Driver
Joined: May 2011
Posts: 5,776
Likes: 443
im sorry, but youre making this much more difficult than it needs to be. confirm your new wiring to be correct....
1) locate, and learn to use, the fuel pump test port located on the drivers side fender by the air filter
2) initiate the test, its damn near impossible to diagnose the fuel system without it.
once test is initiated.....
3) listen for the relay to click. your face will be right in front of the relay when you ground the terminal to initiate the test. if it does click....
4) check voltage at the fuel pump feed. you may have to probe the wires since you had to cut the original harness to accommodate the new tank/pump
if you don't have voltage at the pump, you need to test it at the switch. they go bad too....if you have it at the switch but not at the pump, time to replace the switch or look for broken wires. if you don't have voltage at the switch, need to test voltage input/output. if no voltage is present at the relay input, switch or ground problem.
1) locate, and learn to use, the fuel pump test port located on the drivers side fender by the air filter
2) initiate the test, its damn near impossible to diagnose the fuel system without it.
once test is initiated.....
3) listen for the relay to click. your face will be right in front of the relay when you ground the terminal to initiate the test. if it does click....
4) check voltage at the fuel pump feed. you may have to probe the wires since you had to cut the original harness to accommodate the new tank/pump
if you don't have voltage at the pump, you need to test it at the switch. they go bad too....if you have it at the switch but not at the pump, time to replace the switch or look for broken wires. if you don't have voltage at the switch, need to test voltage input/output. if no voltage is present at the relay input, switch or ground problem.
Thread Starter
|
Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
im sorry, but youre making this much more difficult than it needs to be. confirm your new wiring to be correct....
1) locate, and learn to use, the fuel pump test port located on the drivers side fender by the air filter
2) initiate the test, its damn near impossible to diagnose the fuel system without it.
once test is initiated.....
3) listen for the relay to click. your face will be right in front of the relay when you ground the terminal to initiate the test. if it does click....
4) check voltage at the fuel pump feed. you may have to probe the wires since you had to cut the original harness to accommodate the new tank/pump
if you don't have voltage at the pump, you need to test it at the switch. they go bad too....if you have it at the switch but not at the pump, time to replace the switch or look for broken wires. if you don't have voltage at the switch, need to test voltage input/output. if no voltage is present at the relay input, ecm or ground problem.
1) locate, and learn to use, the fuel pump test port located on the drivers side fender by the air filter
2) initiate the test, its damn near impossible to diagnose the fuel system without it.
once test is initiated.....
3) listen for the relay to click. your face will be right in front of the relay when you ground the terminal to initiate the test. if it does click....
4) check voltage at the fuel pump feed. you may have to probe the wires since you had to cut the original harness to accommodate the new tank/pump
if you don't have voltage at the pump, you need to test it at the switch. they go bad too....if you have it at the switch but not at the pump, time to replace the switch or look for broken wires. if you don't have voltage at the switch, need to test voltage input/output. if no voltage is present at the relay input, ecm or ground problem.
Thread Starter
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
As I understand it I ground the LB/O pin in the data link connector to activate the pump. Is this a case of simply attaching one end of a wire to the LB/O and the other to any ground?
