Fuel leak @ tank?

[Grit dog]

Could use a little advice from someone who’s had a tank out of a square more recently than 1991, lol.
Truck is a 86 K20.
Drivers Side tank has a slight leak. Thinking just when full as tank was plum full. Very small drip coming off the Inside of the tank near the front. More like a wet spot that left a quarter size spot on the floor.
Is the fuel pickup near the front of the tank?
Could be a line or something else typical?
Will see if it dries up after using some gas out of that tank.
What y’all think?
Thanks

 

[75gmck25]

My experience is that it is usually a fuel line. They make a right angle turn to go down to the lines on the frame, so it’s always flexed, and cracks develop in the lines.

Replacing the lines is a PIA because you have to drop the tank a little to reach the clamps on the sending unit end. I used EFI SAE J30R9 hose the last time, in the hope that they won’t need replacing for many years.

Bruce

 

[1987 GMC Jimmy]

If it was at the back and leaking when full to the brim, I’d say check the hose clamp tightness on the filler and vent hoses. Otherwise, defer to what Bruce said.

 

[bucket]

The sender is located more in the center of the tank. The lines cross the top of the frame rail near the center too.

 

[Grit dog]

Good info gents, thank you. I could be leaking anywhere and just coming out a hole in the tank shield up front, I'll look a bit closer and see if it's just when full or all the time. It wasn't enough to leave a noticeable spot on asphalt when it sat outside.
I'll likely kick the can down the road unless it gets worse as the bed will come off when I paint it at which time any lines or leaks can be easily replaced or repaired.

 

[75gmck25]

I got the bright idea to jack up the truck bed to access the sending units and lines. I loosened the bolts, disconnected the fillers, and started jacking up the bed. At the point where I had two stacked 2x4s between the bed and the frame I realized I would need to raise the entire bed at least a foot to get the clearance to reach everything. Also, I could not just jack up the front because the angle meant it had to go even higher in the front, and at some point the bed might start sliding back. If any of those 2x4s slipped when I was working I would have an arm or hand sandwiched between the bed and frame. I decided it might turn out badly if I kept going. Just another couple of hours wasted.

Bruce