Fuel Delivery

Ohmess

Ohmess

I wanna DRIVE!
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So, Annabelle is back on her wheels after roughly three months on jack stands, but she didn't start yesterday.

The problem is not a new one; it existed prior to the tranny swap. I have a fuel pressure issue. The prior owner replaced the fuel pump prior to my acquisition a year ago, but I am still not getting sufficient fuel pressure.

I have found two spots near one another in the fuel line where the line is dented almost flat. The surrounding area also shows signs of an impact, underneath the left rear seat. On my car the fuel line runs down the long axis of the car on the left side, and is tucked under a 90 degree bend in the sheet metal underneath the door sill. It makes a 90 degree inboard turn just in front of the "push rod" bolted to the floor and the subframe mounts, then turns 90 degrees again and continues toward the back of the car for several inches. Immediately after this second 90 degree turn is where my two dents are located. This is the most exposed area of the hard line. I am concerned that a repair here would potentially get hit again.

So, I am thinking about replacing the entire hard line, not only to correct this issue, but also because I will be needing to install an electric fuel pump to accommodate the triple weber carb setup and running the line to enable the pump install near the dif would simplify the fuel lines inside the trunk.

I know a little about bending pipe and flaring and whatnot, but my concern relates to the mounting clamps that hold the hard line to the car. How tricky are these to mess with, and will I be risking damage to the sheet metal holding the clamps if I go down this path?
 
Two follow up items on this:

1) A buddy of mine suggested that the kinked pipe may not be the problem (mine is not badly enough damaged), so I went hunting for an air leak. Lo and behold, I had a rather substantial leak around the fuel level sender. I had recently installed a new BMW O-ring, and so this was rather disappointing. I did remove a little rust around the perimeter of the hole for the sender, but only used steel wool and did not think I distorted the shape of the metal at all.

So, I've ordered a couple of slightly larger o-rings from an o-ring supplier in an attempt to seal this up.

2) As to the clips holding the fuel line to the body, upon closer inspection they appear to be a pair of metal ears wrapped around a 8mm rubber bushing that had been installed on the line. The ears are merely bent around the bushing to hold the pipe. It looks like the line can be removed by carefully bending the ears outward, and that the ears can be reused.
 
2). Correct. Many times the pipe gets flattened due to incorrect jack placement. You can also buy clips from an e28 that that use a sheet metal screw to hold the pipe which is what I had to do when I added a return line for the b35. Especially handy up above the rear subframe. The hose to sender unit can also leak air and the hoses up front can look fine but tiny holes allow air to enter without leaking any gas. It has to be airtight everywhere.
 
The high pressure fuel line is still available from BMW. I ran the line up against the L channel and used the exiting metal tabs to hold the lines againts the L channel. The line bends its way up to the engine bay as you described and it ends right by the CSI fuel pump. You can use a BMW fuel clamp off an e28 or e30 chassis car, they look nice and will get the job done.
 
Volume drops from smaller openings or reducers.
Run a pressure and volume test.
 
Just to be clear- your fuel tank is vented. Look on the far side of the filler neck.
The o ring keeps gas in the tank from sloshing out- that's all
 
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