rusted gas tank

[Montreal525]

Norbert is really good, I go see him for all the major issues... He's the one who did the rebuild on my my tranny 2 years ago and it's been smooth sailing since...

Jeff

[525i winter driver]

I cancelled today with Norbert - Last night I went for a long drive to empty the tank a bit. For the first time ever the engine completely cut out on me - still had electrical power but the motor completely died like I had turned the key off. The tank was about 40% full and the engine was fully warm and I was doing about 50km/h (not accelerating) up a slight incline. After I pulled over for a second (wtfwt?) it started up again right away like nothing happened. As I think I mentioned I've been experiencing a mysterious idle roughness lately (thought alternator but maybe water in tank?) and very occasional hot start troubles. I'm starting to think maybe I'd rather replace this tank than fix it. I also get a bad (zero) fuel level reading below a quarter tank and I want to know if it's the wiring or the sender unit before I get the tank dropped (I was going to tackle this problem when it was warmer but I'm going to figure that out tomorrow I hope).

So yeah guys, I think I am in the market for a gas tank and I don't think I want one that's been lying around in any scrapyards here over the last few months (or weeks even). You'd think I'd know something about shipping...

Norbert won't do a used one (but I know a couple of good people who would) and he won't repair mine if it's too cruddy (good)- found out this morning I know someone else who takes his e32 to him and he says nothing but good things. I might just bite it and get a new one but I have to replace the windshield really soon too and I am going oh so broke with this car. decisions, decisions...

[BMWDriver]

I get the same issue on the gas gauge. I've replaced a leaking capacitor in my cluster, and the problem lessened. It was at a point where the tank would show empty erratically when I got to half or less. The thing's still not quite accurate though I might add. Not a big deal for me since I like to fill her up before it gets on empty. Less money at a time.

As far as your engine cutting out, it sounds like the fusible link is the problem. You'll see a good description of its associated problems on bmwe34.net, a great reference. An easy fix.

[525i winter driver]

I get the same issue on the gas gauge. I've replaced a leaking capacitor in my cluster, and the problem lessened. It was at a point where the tank would show empty erratically when I got to half or less. The thing's still not quite accurate though I might add. Not a big deal for me since I like to fill her up before it gets on empty. Less money at a time.

As far as your engine cutting out, it sounds like the fusible link is the problem. You'll see a good description of its associated problems on bmwe34.net, a great reference. An easy fix.

I don't think the gas guage is a capacitor problem as the obc reading freezes at the same point that the guage needle goes to zero. this is the only problem i have with the cluster. i checked the fusible link symptoms but they don't seem to match. i didn't lose any electrical power at all, even for a second - the engine just died on me but started up again first time. thanks for the suggestions!

[BMWDriver]

I also had erroneous readings on the OBC for the gas tank. The plunger was good as Norbert confirmed. You have to remember that the OBC and cluster are linked together and get the information from the same electrical source. The plunger in the gas tank will produce resistance depending on where the buoy is. If that works all right, then the electrical power that goes through to it is probably toast. Capacitors are like batteries, only they don't store the energy. So the one that sends a signal to the gas tank is probably weak so sends not enough energy to it passed a certain point.

But, we do have old cars. And that happened to me often in the first few months I had the car since I gased up late (at a time when gas was cheaper!). I found out I had at least 20 liters (1/4) in when I gased her up then.

If you can live with that as I have decided, then there is no more problem.

[525i winter driver]

I also had erroneous readings on the OBC for the gas tank. The plunger was good as Norbert confirmed. You have to remember that the OBC and cluster are linked together and get the information from the same electrical source. The plunger in the gas tank will produce resistance depending on where the buoy is. If that works all right, then the electrical power that goes through to it is probably toast. Capacitors are like batteries, only they don't store the energy. So the one that sends a signal to the gas tank is probably weak so sends not enough energy to it passed a certain point.

that is good info, i didn't realize the current originated at the cluster, i thought it came from the check control module. i would like to test the wires before i replace the tank to confirm the level sensor is not the problem. can anyone tell me is there an expected current that i can test for on the blk/red/yel wire leading to the fuel sensor?

[BMWDriver]

That one turns on the light indicator saying the fuel is very low (switch to turn the red light). I'd go with the other one beside it which is showing that it's the variable resistance the buoy should give.

Come to think of it, do both. Hopefully you know what figures to expect.

[ahlem]

Doesn't POR have a gas tank repair process for sealing up the inside?

[ahlem]

OK, so what thread did this end up on?