Kerbal Space Program

Confirmed using the attached craft file. Not sure what's going on. I've removed the radial fuel lines, as well as the fuel line in the cargo bay, and the bug persists.

I wasn't able to duplicate by building a vessel in the SPH, so trying to figure out which part is causing the problem.

i've reproduced. The back fuel tank was accidently attached to the SC-9001 Science Junior and this tile is causing the issue.

build a simplier plane for testing:

Reproduction steps:

Build the plane in hangar, placing parts in the following order:
1. MK2 Cockpit
2. MK2 LF fuselage
3. Small Girder
4. Materials Bay
5. MK2 Cargo Bay

Next, use the offset tool to:
1. Offset Girder into the forward LF tank.
2. Offset the Cargo Bay forward to join up with the forward LF tank.

Finally, add the following:
1. Aft LF tank
2. Jet engine (Panther)
3. Air intake
4. Launch clamps if you want them

I've attached some photos of the assembly process, as it gets a little confusing.
edit- I just noticed the photos don't appear in order in the tracker report. Use the numbers next to the photos for the assembly order..

just more simplier steps to reproduce:

0. build a new vessel in hanger or VAB
1. start with a pod
2. attach a fuil tank (doesn't matter which
3. attach SC-9001 Science
4. attach another fuel tank
5. attach a jet engine
6. attach an intake source

edit all without offset or clipping parts!

Changed subject to reflect the issue better.

Issue also is present with Rapier engine, even in closed-cycle mode.

Does not seem to affect LFO engines other than the Rapier in closed-cycle.

Some further testing:

tried to replace the SC9001 Science Jr (Materials Bay) with some other object and couldnt reproduce
it affects all fuel tanks attached behind SC9001 Jr
if you attach an external fuel duct, bug is again removed
bug only effects if its placed between fuel tanks