Does a '91 318is have one opening or two on top of fuel tank?

[Lavalamp]

About to order a fuel tank for my 318is, and I recently bought one for my 325es that's listed cheaper than a 318is one. But realoem has the same part #s for both and other sources I've looked at make it seem like they're the same.

But I thought I remembered some e30s having two openings at the top (under the seats, is that real or am I thinking of something else?

So yeah, just wanted to double check before I ordered it, so one opening or two?

[Dj Buttchug]

late 318is cars have only one opening for fuel pump and sender. Early 318i cars are the same. all m20 cars (i believe) at least late m20 cars have two openings for dual fuel level senders due to different tank sizes and fuel gauges.

if you are ordering a tank for a 318is you want the one with only one opening.

[Lavalamp]

Great, thanks for the reply.

Looked up a late 325 on realoem and they do have two openings as you said. My 325es is an 86 so it only has one opening and seems to be the same tank as my 91 318is, so that will save me a few bucks.

[Lavalamp]

actually, could the 325es have a bigger opening because of the primer pump and the 318is a smaller opening for just the fuel sender?

[jlevie]

The 55L tanks as used on all 318's, 9/86-8/87 325is, and all ETA cars are all the same and have a single opening on the right side of the tank. The 63L tank used on 325's from 9/87 have two openings, one on each side of the tank.

[Lavalamp]

Thanks for clearing that up!

Now, another random thought... Would the larger tank fit in a 318 and just cap the other hole off?

[jlevie]

Yes, but the fuel gauge won't read correctly. The 55L tank has a cross-over tube that allows the fuel to equalize between the tank halves. The 63L tank uses a siphon driven by returning fuel to move fuel from the left side to the right. A level sensor goes in the left hand side and the two sensors are wired in series. The gauge in the cluster is also different.

If you want to use the 63L tank you need to add the left sensor and replace the gauge in the cluster with one from a 9/78 or later 325i/is/ic.