Aft-axle fuel tank access on 85

[Sergey]

Hello forum ladies and gentlemen from a new member. I am long time reader of this forum -
thanks for all the help that I've gotten from the collective wisdom.

I own 1985 F250 with 6.9 for the last 25 or so years, and used to know it from the inside. But getting older .... so it is time to ask.

Truck is 99% original stock configuration to the degree my abilities and budget allowed it to be kept.

The aft axle (rear) fuel tank may need attention, finally. User manual has instructions and pictures how to remove rear tank. Which state that fill hose, fuel lines and electrical connector must be disconnected prior to removing tank straps to free it.

Yet what I see does not match manual instructions above. Rear tank electrical connector and fuel line connectors are not accessible - unless truck bed is removed? Is it really the case?

Thank you,
Sergey

 

[nj_m715]

welcome, I worked on my 89 and I was able to reach up there. drop the tank a few inches makes it much easier

a lot of guys here pull the beds, some dont. I didnt

 

[Sergey]

welcome, I worked on my 89 and I was able to reach up there. drop the tank a few inches makes it much easier

a lot of guys here pull the beds, some dont. I didnt

Thanks for the advise. It does not seem that dropping rear tank a little bit will help in my case. Doing so will just stretch fuel lines and electrical cable by pulling them down. I would avoid putting such strain on 35 years old electrical cable or nylon pipe (will try to attach photo to aid understand my issue).
I cannot even stick my hand in there to feel the connectors.

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[gandalf]

I just went out to look at my truck. You're right, you can't get your hand in there as it is right now.

That leaves two possibilities. You can remove the bed, as I did. Then the connections are out in plain sight. Or you can drop the tank a very little bit, just enough to get your hand in to undo the connections. You might gain enough room by simply loosening the bolts on the front end of the bottom straps, but I don't think so. The problem is that cross member. You'll probably have to drop the tank enough to get your hand up there between the cross member and the tank. Be sure to loosen the vent line so it just dangles. and loosen the fuel lines and the electrical from any attachments, trying to gain any slack. Have support, like a floor jack, under the tank, holding it up so it doesn't suddenly drop to the ground. That tank is heavy and awkward, and very much worse if there is any fuel in it. Try to have the tank empty.

I'll toss in 3 pictures of mine, a '92 CCLB dually, when I had the bed off. That will give you some idea what you're dealing with when you're feeling around up there in the dark where you can't see.

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[nj_m715]

"I cannot even stick my hand in there to feel the connectors."
thats why I lowered the tank a few inches

 

[riphip]

I remove the bed whenever I have to work on fuel tanks also. Much easier (for me)

 

[ih8minimumwage]

I just did the pickups on my tanks in my 86. If you have access to a floor jack, place that under the tank with a block of wood, pull the rear hardware for the straps and lower the tank at an angle. You can then dig in and release the wiring and fuel lines.

Just make sure you've run it as far out of fuel as possible, and it doesen't end up weighing much at all.

 

[aggiediesel01]

If the removal of the tank is your end goal because it's leaking or known to be damaged in some way then lowering it just enough to reach what you need to on it's way out might be your easiest solution. If you have an unknown issue with the sending unit/pickup tube and it would be helpful to have the tank in place while you diagnose electrical connection or fiddle with fuel line or pickup tubes or tank level sensor then lifting the bed is probably a better solution for you. You don't have to remove it completely, just unbolt it, disconnect the rear wiring harness and put a couple 4x6 or larger timbers in between the bed and frame on the driver or or both sides. I'm pretty sure you can leave the fill necks connected in this case because they route over the frame rail. That will give you enough room to get some real work done in there without mashed/cut hands and a crick in your neck.

 

[Ky85]

that frame looks nice and clean

 

[bruce bashor]

Hi all have an 87 f350.what I did was cut an access panel so I could disconnect the lines old work truck so it wasn't a problem as far as looks

 

[Sergey]

Thank you for your helpful replies.
To clarify about the goal. For the last 15 years or so the rear tank in my truck only takes about 11 gallons of fuel, while being stock with 19 gallons capacity. I did not bother/was not able/health issues/etc. for so long to investigate it. I probably would not even now but then sending unit went out on it a few years ago (finally, after so many years, not bad). Cleaning rear tank should be helpful after so many years of various fuels in it.

We had a couple of sunny days here lately ( I can only work on this truck outside in driveway, weather permitting). I attempted to follow the route of lowering the tank a bit to disconnect fuel lines and sending unit cable. Sadly I did not make good progress. There is some slack in fuel lines made by unclipping them (and all plastic clips I touched broke on contact) which allowed me to lower fuel tank a little.

The blocker issue is in my inability to unplug connections. What seems to happen that I can reach those and feel with my fingers, but unable to unplug because I cannot see work area. I.e. as if working blind.
Also, sending unit connector - by feeling of it can be described as one blob of tar, cannot even tell if it has a locking tab.

Paused this work for now.

Removing tuck bed option - would be nice, but have no crane access or hoist.
Sergey

 

[IDIBRONCO]

Removing tuck bed option - would be nice, but have no crane access or hoist.

Sometimes you need to find a few helpers and some cold beverages to get this done.

 

[aggiediesel01]

The bed doesn't have to come off. Get some blocks and one man and a jack can lift and block/repeat until it's high enough to get at what you need.

 

[Sergey]

Continued this work. Spent some time to clear tar, mud and gum from electrical connector of sending unit. Worked blindly (i.e. without seeing it) as I cannot lower rear tank enough to stick my head there, using wood chip as tool.
Now I can feel there is a tab on this connector head.

Can anyone tell me - in order to disconnect the sendng unit connector, shall the tab be
a) pushed out while pulling connector away from sending unit
or
b) squezzed into connector while pulling it

Thanks

 

[gandalf]

I can't remember what year truck you have, but I can't see that this feature would change terribly much.

I'll include 2 pictures from my '92. One is of the rear tank, and one of the front tank. Again, Again, I can't think that they will change connector types from one to the other. The pictures are self-

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explanatory.