Fuel tank mod

[e30s50dan]

Yea. I checked out the site. They also sell small accumulator tanks. I'm afraid the small foam cubes would float around.... Damn,why can't someone come up with an EASY fix?

[JakeP]

They won't float around if you put enough in there. You need to pack it in!

[Snowmann]

Any close up pics of how you went thru the tank wall with the 1/8" plate? I'm assuming the fittings are compression style given the tube used... But trying to figure out how you successfullly created a bulkhead style fitting with this plate concept...

[jlevie]

Any close up pics of how you went thru the tank wall with the 1/8" plate? I'm assuming the fittings are compression style given the tube used... But trying to figure out how you successfullly created a bulkhead style fitting with this plate concept...

The bulkhead fitting is really pretty simple. I drilled and tapped a 2x2x1/8" piece of steel plate for 3/8NPT. The brass fitting is a 3/8" compression to NPT elbow. The NPT side (that winds up in the tank) was drilled out to accept 3/8" soft copper tubing which was soldered into place after bending and trimming. I formed that tubing to generally follow the existing fuel feed tube from the siphon.

I used JB weld on and around the threads of the elbow. The bulkhead plate was then attached to the tank with four pop rivets with JBweld between the plate and the tank.

[Snowmann]

The bulkhead fitting is really pretty simple. I drilled and tapped a 2x2x1/8" piece of steel plate for 3/8NPT. The brass fitting is a 3/8" compression to NPT elbow. The NPT side (that winds up in the tank) was drilled out to accept 3/8" soft copper tubing which was soldered into place after bending and trimming. I formed that tubing to generally follow the existing fuel feed tube from the siphon.

I used JB weld on and around the threads of the elbow. The bulkhead plate was then attached to the tank with four pop rivets with JBweld between the plate and the tank.

I'm assuming you just didn't want to weld as it was a used tank?

My plan is a npt weld bung with basically the same component list as yours...

[jlevie]

I'm assuming you just didn't want to weld as it was a used tank?

My plan is a npt weld bung with basically the same component list as yours...

Correct. While it is possible to weld on used tank by filling the tank with inert gas, it is easier to attach the fitting they way I did.

A better alternative, which I wasn't aware of at the time, is to replace the in-tank high pressure pump with one from a late production 318is. That pump has a return fitting which eliminates the need to fabricate same.

[Snowmann]

Well damn... That's the part of the puzzle I don't have... Looks like we're going that route.

[Snowmann]

Jim,

Did you modify the tank in anyway to fit the transfer pump to the driver side?

Mine when installed and spun to lock is indexed with the feed line facing to the drivers side (180 degrees from yours)

The tabs on the fuel pump hole in the tank are different sizes and appear to only allow the pump to index this way.

[jlevie]

I had to trim one tab slightly to allow the pump to be in the desired orientation. A minute or so of work with a fill will get the job done.

[blueapplesoda]

Nice mod. Didnt the e21's and some vw have some sort of fuel "capacitor" thing? I swear I've seen something like that to battle our starvation issues.

[nando]

Nice mod. Didnt the e21's and some vw have some sort of fuel "capacitor" thing? I swear I've seen something like that to battle our starvation issues.

that was a different thing altogether, and some E30s had them too. it was a fuel damper that was meant to reduce pulses/harmonics in the fuel lines themselves, because they were typically single batch fire fuel injection which meant that the pressure at the rail would vary wildly with each injection pulse.

[priapism]

Did it fix your starvation? Seems everyone I've talked to that's tried to fix it has only made it worse, us included.

[jlevie]

Did it fix your starvation? Seems everyone I've talked to that's tried to fix it has only made it worse, us included.

There are two ways to prevent fuel starvation. A surge tank fed by a transfer pump and that tank feeding a high pressure pump is one solution. The other solution is to a pump move fuel from the left side of the tank to a high pressure pump in the right side.

Well, I guess there is a third solution. That being installation of a fuel cell.

[einstein57]

Nice mod. Didnt the e21's and some vw have some sort of fuel "capacitor" thing? I swear I've seen something like that to battle our starvation issues.

Yes the early model vw golfs and jettas that used a dual pump setup similar to the e30 used a fuel accumulator. They cost a shit ton so don't run out to your local vw dealer to get one. IIRC ireland sells a cheaper accumulator for under $100. Its rumored to be a cheaper audi accumulator but no one ever post a picture or part number. I plan on purchasing one when I get my car back together.

[TobyB]

Hey, Jim,
nice trick- thanks, all for bumping it back up ttt.
Timely, too, as I've got both early and late tanks, and all the pumps from both,
but haven't started putting one back together in the car.

And yes, if you get some tubing, you can compress fuel cell foam and then feed it into
the tank to foam it. Perhaps not a perfect solution, but it might help with fuel movement
and certainly with explosion.

t