Front fuel tank help
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Front fuel tank help
I've read through a ton of stuff concerning fuel tanks which have helped orient me to how the whole system works. BUT, my lovely truck has some interesting features which makes it a little different that the "standard f250".
Here's the details:
Truck will run when driven with no problems if on rear tank. Once flipped to front tank, will drive for about 10 miles on the freeway before the "fuel filter" light comes on, then the truck will die shortly after than.
Electronic fuel pump with on dash toggle switch which really throws me off. Do these trucks have a fuel pump in the tank and along the fuel line? If so, I assume that either the dash selector or the in tank fuel pump is bad. Any way to test either of these?
Huge thanks for any help.
Here's the details:
Truck will run when driven with no problems if on rear tank. Once flipped to front tank, will drive for about 10 miles on the freeway before the "fuel filter" light comes on, then the truck will die shortly after than.
Electronic fuel pump with on dash toggle switch which really throws me off. Do these trucks have a fuel pump in the tank and along the fuel line? If so, I assume that either the dash selector or the in tank fuel pump is bad. Any way to test either of these?
Huge thanks for any help.
Logistics Pro
Joined: Sep 2007
Posts: 3,737
Likes: 179
From: Western Mass
No pump in the tanks unless someone added one. Stock they just use the mechanical pump on the block and suck from the tanks. The selector switches which tank gets sucked from.
Could be stuff blocking up the pickup in the tank. Search for the "showerhead" issues people have had. Might also be a restriction or clog in the line from the front tank to the selector valve. Where is the electric pump that the toggle switch controls?
Could be stuff blocking up the pickup in the tank. Search for the "showerhead" issues people have had. Might also be a restriction or clog in the line from the front tank to the selector valve. Where is the electric pump that the toggle switch controls?
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Senior User
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No pump in the tanks unless someone added one. Stock they just use the mechanical pump on the block and suck from the tanks. The selector switches which tank gets sucked from.
Could be stuff blocking up the pickup in the tank. Search for the "showerhead" issues people have had. Might also be a restriction or clog in the line from the front tank to the selector valve. Where is the electric pump that the toggle switch controls?
Could be stuff blocking up the pickup in the tank. Search for the "showerhead" issues people have had. Might also be a restriction or clog in the line from the front tank to the selector valve. Where is the electric pump that the toggle switch controls?
Good to know that there is no "in-tank" pumps. But, sounds like I may need to just lower the front tank and start inspecting all the components. How difficult is it to drop the front tank on one of these whales?
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
Are you sure that's a pump you're hearing, and not the tank switcher valve itself? Is the tank selector switch in the dash factory or aftermarket? Do you hear it make any noise when you turn the key to RUN, or only when you flip the selector switch?
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tank selector switch is factory as far as I can tell.
no noise when I turn the key to RUN. pump noise is independent of position of selector switch.
any advise?
Logistics Pro
Joined: Sep 2007
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From: Western Mass
Sounds like you know what you're looking at then. Dropping the tank is a pain if its full, not too bad if its close to empty. If theres a lot of fuel in it, try to siphon it out first. You can balance the tank on a regular jack to make it easier, a transmission jack works better though if you have one (wider area to balance).
Loosen up the straps and drop the tank down a little bit to get better access to the connections. You'll have the two plastic feed/return lines to remove. You have to pop out the little plastic clip, then they slide right off. A couple small flathead screwdrivers usually work for that. Then the larger fill line which is attached by a hose clamp. Oh and the wires for the tank sender are there too.
Loosen up the straps and drop the tank down a little bit to get better access to the connections. You'll have the two plastic feed/return lines to remove. You have to pop out the little plastic clip, then they slide right off. A couple small flathead screwdrivers usually work for that. Then the larger fill line which is attached by a hose clamp. Oh and the wires for the tank sender are there too.
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so, did 1993 f250s have in-tank fuel pumps, but 92 did not?
Reason I ask is because I just read this, and it sounds just like my truck..... Would love to solve my hard starts with replacing a few check valves.
From - Ford F250 Dual Fuel Tank Problem
Here's a story from a reader about a problem with hard starting and fuel tank woes on Ford F250s.
Okay, here's the story. There is a recall kit for several years of F-250 trucks (including 93) which consists of two in-line check valves and a new fuel pressure regulator. The valves go in the supply line from the fuel pumps to the tanks and prevent fuel from flowing into the tanks from the supply lines. This kit was issued by Ford to prevent two problems: fuel flowing from one tank into the other through the supply lines, and long cranking times due to fuel running back into the tanks after the vehicle was shut off.
The pressure regulator was included as good practice. In my case, I had the two valves and the pressure regulator installed. Sure enough, the long cranking time stopped, but I still had fuel going from one tank to the other. Yes, I verified that fuel was flowing from one tank to the other. The final solution was to replace one of the fuel pumps (only one because Ford wants ~$250 for the things and if that WASN'T the problem, I wasn't out $500). Voila! I replaced the front tank fuel pump, and fuel would still flow from the rear to the front, but NOT from the front to the rear. I will replace the rear pump in a couple of weeks, and the problem will go away completely. The problem seems to be that the fuel pumps were going bad, and not putting out enough pressure to open the return valves in their own tanks, but putting out enough pressure to flow through the return valve in the OTHER tank.
Let me explain. In one of Ford's "better ideas", some turkey decided that each fuel pump should have its return line flow through the pump assembly through a valve. Okay. Not how I would have done it, but okay. However, to make the valve open only when that pump was activated, a minimum amount of pressure must be maintained in order to open the valve sufficiently so that fuel can return ONLY through that valve. The problem is that when that minimum amount of pressure is not available, fuel will flow through the *other* tank's return valve, which is what was happening to me. I suppose it's another way to indicate that a fuel pump is going bad, but it seems like a simple pressure sensor would be better. And cheaper. Anyway, that's what it was. Runs great now. I highly recommend anyone who has one of these trucks and is experiencing the long start-up time to get the valves placed in the lines. It solves the problem immediately.
Thanks for the time. --Dana Burgess
Reason I ask is because I just read this, and it sounds just like my truck..... Would love to solve my hard starts with replacing a few check valves.
From - Ford F250 Dual Fuel Tank Problem
Here's a story from a reader about a problem with hard starting and fuel tank woes on Ford F250s.
Okay, here's the story. There is a recall kit for several years of F-250 trucks (including 93) which consists of two in-line check valves and a new fuel pressure regulator. The valves go in the supply line from the fuel pumps to the tanks and prevent fuel from flowing into the tanks from the supply lines. This kit was issued by Ford to prevent two problems: fuel flowing from one tank into the other through the supply lines, and long cranking times due to fuel running back into the tanks after the vehicle was shut off.
The pressure regulator was included as good practice. In my case, I had the two valves and the pressure regulator installed. Sure enough, the long cranking time stopped, but I still had fuel going from one tank to the other. Yes, I verified that fuel was flowing from one tank to the other. The final solution was to replace one of the fuel pumps (only one because Ford wants ~$250 for the things and if that WASN'T the problem, I wasn't out $500). Voila! I replaced the front tank fuel pump, and fuel would still flow from the rear to the front, but NOT from the front to the rear. I will replace the rear pump in a couple of weeks, and the problem will go away completely. The problem seems to be that the fuel pumps were going bad, and not putting out enough pressure to open the return valves in their own tanks, but putting out enough pressure to flow through the return valve in the OTHER tank.
Let me explain. In one of Ford's "better ideas", some turkey decided that each fuel pump should have its return line flow through the pump assembly through a valve. Okay. Not how I would have done it, but okay. However, to make the valve open only when that pump was activated, a minimum amount of pressure must be maintained in order to open the valve sufficiently so that fuel can return ONLY through that valve. The problem is that when that minimum amount of pressure is not available, fuel will flow through the *other* tank's return valve, which is what was happening to me. I suppose it's another way to indicate that a fuel pump is going bad, but it seems like a simple pressure sensor would be better. And cheaper. Anyway, that's what it was. Runs great now. I highly recommend anyone who has one of these trucks and is experiencing the long start-up time to get the valves placed in the lines. It solves the problem immediately.
Thanks for the time. --Dana Burgess
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Can anyone tell me what the unit is that all the fuel lines from the fuel tanks goes into that rides in the driver side frame? It has 4 fuel lines entering and only 2 leaving to go to the engine. It is leaking a good amount of diesel. I'm assuming that could be part of my hard start issues. also wondering what to search for to fix it.
New unit?
New o-rings?
Thanks
EDIT: Found the answer, Fuel tank selector valve. And they are pricey apparently. Sheesh.
One more thing that may help diagnose this issue for those of you in the know, when I flip it to the front tank on the dash, it shows that the fuel tank is WAY full. As in, it looks like I crammed two tanks of diesel into the front tank according to the gauge. Needle is completely pegged in the full position.
New unit?
New o-rings?
Thanks
EDIT: Found the answer, Fuel tank selector valve. And they are pricey apparently. Sheesh.
One more thing that may help diagnose this issue for those of you in the know, when I flip it to the front tank on the dash, it shows that the fuel tank is WAY full. As in, it looks like I crammed two tanks of diesel into the front tank according to the gauge. Needle is completely pegged in the full position.
Logistics Pro
Joined: Sep 2007
Posts: 3,737
Likes: 179
From: Western Mass
The selector valve also switches the wires running from the senders. So either that part is having an issue, or the sender on the front tank has a problem.
Its possible that one of the lines running to the selector valve is cracked, or the connectors are cracked. There is an o-ring somewhere in connectors that potentially could leak. Figure out where the leak is actually coming from before buying new parts. Don't want to buy a new valve to only have a bad hose. And yes, the leaks will cause hard starts.
Its possible that one of the lines running to the selector valve is cracked, or the connectors are cracked. There is an o-ring somewhere in connectors that potentially could leak. Figure out where the leak is actually coming from before buying new parts. Don't want to buy a new valve to only have a bad hose. And yes, the leaks will cause hard starts.
Lead Driver
Joined: Mar 2006
Posts: 5,100
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From: western SD
I've read through a ton of stuff concerning fuel tanks which have helped orient me to how the whole system works. BUT, my lovely truck has some interesting features which makes it a little different that the "standard f250".
Here's the details:
Truck will run when driven with no problems if on rear tank. Once flipped to front tank, will drive for about 10 miles on the freeway before the "fuel filter" light comes on, then the truck will die shortly after than.
Electronic fuel pump with on dash toggle switch which really throws me off. Do these trucks have a fuel pump in the tank and along the fuel line? If so, I assume that either the dash selector or the in tank fuel pump is bad. Any way to test either of these?
Huge thanks for any help.
Here's the details:
Truck will run when driven with no problems if on rear tank. Once flipped to front tank, will drive for about 10 miles on the freeway before the "fuel filter" light comes on, then the truck will die shortly after than.
Electronic fuel pump with on dash toggle switch which really throws me off. Do these trucks have a fuel pump in the tank and along the fuel line? If so, I assume that either the dash selector or the in tank fuel pump is bad. Any way to test either of these?
Huge thanks for any help.
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Senior User
Joined: Feb 2013
Posts: 125
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So i've eliminated the FSV and gone with manual valves which I like. And i left the FSV on there to enable me to check the fuel level in the tanks with the tank selector on the dash. Front tank still doesn't send any fuel to the engine though. And the gauge on the dash still has the front tank pegged at FULL all of the time.
2 issues at play here.
1. Fuel delivery from the front fuel tank to the engine.
I'm (soon I hope) going to drop the front tank and figure out what the heck is going on back there. Either it's restriced between the tank and the newly installed fuel hose, or the fuel is simply not being picked up because something is broken with the sender unit I figure...
2 Gauge pegged at full.
This is really where I could use some help. Does anyone know how to test the wires between the front fuel sending unit and the dash gauge. Any advice on troubleshooting would be much appreciated. Maybe I'll drop the tank and find my problem though. It sounds like it is "grounded" in order to be pegged full...
2 issues at play here.
1. Fuel delivery from the front fuel tank to the engine.
I'm (soon I hope) going to drop the front tank and figure out what the heck is going on back there. Either it's restriced between the tank and the newly installed fuel hose, or the fuel is simply not being picked up because something is broken with the sender unit I figure...
2 Gauge pegged at full.
This is really where I could use some help. Does anyone know how to test the wires between the front fuel sending unit and the dash gauge. Any advice on troubleshooting would be much appreciated. Maybe I'll drop the tank and find my problem though. It sounds like it is "grounded" in order to be pegged full...
Lead Driver
Joined: Oct 2003
Posts: 8,476
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From: Madison, WI
Pegged full means the circuit is OPEN, not shorted to ground. The wires don't go from the sending units to the dash gauge, they go from the sending units to the switching valve, then to the dash gauge. Here's a diagram: http://userpages.chorus.net/elephant...nkSelector.pdf . That C421 connector is on the frame, next to the front fuel tank (just follow the wiring harness from the sender). Check the resistance between the blue/yellow and black wires going to the sender. If you put a jumper between the blue/yellow and black wires on the harness going to the selector, the gauge should drop to empty. If so, that confirms the wiring is good from there forward, and the problem is with the sender and/or the wiring from the sender to the connector on the frame.
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Pegged full means the circuit is OPEN, not shorted to ground. The wires don't go from the sending units to the dash gauge, they go from the sending units to the switching valve, then to the dash gauge. Here's a diagram: http://userpages.chorus.net/elephant...nkSelector.pdf . That C421 connector is on the frame, next to the front fuel tank (just follow the wiring harness from the sender). Check the resistance between the blue/yellow and black wires going to the sender. If you put a jumper between the blue/yellow and black wires on the harness going to the selector, the gauge should drop to empty. If so, that confirms the wiring is good from there forward, and the problem is with the sender and/or the wiring from the sender to the connector on the frame.
I know next to nothing about testing circuits. I'm hoping what you just wrote makes more sense when I'm down there looking stuff over, but I may need your help again in the future. Hopefully I get around to dropping the tank soon and see what is going on...
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