Fuel level reading not correct, what's up?

[bigdrick323]

What do I need to purchase or do?

I am away from my computer, being lazy!

[jlevie]

My suspicion is that one of the level sensors is bad.

[bigdrick323]

I have a '88 325i and my gauge only goes to halfway even when full and drops to 0 when it has "who knows" amount of gas. Ideas?

[Jean]

^ yep, amazing how often this comes up.

[jlevie]

You have a cluster with a fuel gauge meant for a late tank with two level sensors in a car who's fuel tank only has one sensor. Pull the cluster and replace the fuel gauge with one meant for an early car.

[lookitsranday]

sorry to bring old thread to life. i just got a 84, and the PO swapped cluster to i cluster because he also did m20b25 swap. now my fuel gauge is reading 1/2 as empty. i read somewhere that if i leave old ETA cluster but swap out the tach gauge it should be fine? (since i motor 7k rev.)

[bernzpeed]

i Have the same problem with this guys. I did an engine swap from an 87 325i to an 89 325i. I used the same cluster and si board from the 87 to the 89. Now it's reading the full tank at half tank. When I reach empty, I put gas in and tank will stop 5 gallons after. Is it the fuel sender or the gauge?

I don't know how to use a multimeter but I do have one so I can check the ohm reading if someone teaches me how to do it, please.

Thanks! On the good side, I will never run out of gas since I always have to pump fuel every 5 gallons...lol.

[Jean]

Gauge will work if it's the wrong one, that's normal. Early cluster = no coding plug in the front.

What is the color of the back of the cluster is it blue or white? If it's blue it's late model.

[91 318is]

Damn this is confusing, I'm getting lost.

I can tell you that before my swap my early model m20 car, with early model cluster and fuel gauged worked fine but the light didn't work.

With the m52 I put in a late model cluster and the gauge didn't work, it was at 1/2 when it was empty.

I put my early model gauge into the late model cluster and now it reads over 1/2 when it's full.

I've given up messing with it, and I fill up every 150 or so miles.

Damn dude, why did you change the cluster so much?

You are getting close. Did the cluster you tried work 100% in another m42 car? (89 M42 ??)

Yeah it was 100% working in my buddies car.

I'm almost 100% it's the fuel gauge now. But I don't understand why this gauge works, when it's not the correct gauge for my car.

I wonder if my original cluster is a early model cluster?

[Jean]

Here's another thing I found. I pulled my buddies 89 cluster apart to look at the fuel gauge part # and it's different then the other 2 gagues I tried.


This one reads:

9 3030 150 80

1 374 822


The other 2 gauges have this same part #1 381 366


So it looks like I have the wrong part number fuel gauge? According to realoem, I'm suppose to have # 1 381 366

You are getting close. Did the cluster you tried work 100% in another m42 car? (89 M42 ??)

[87e30]

Damn this is confusing, I'm getting lost.

I can tell you that before my swap my early model m20 car, with early model cluster and fuel gauged worked fine but the light didn't work.

With the m52 I put in a late model cluster and the gauge didn't work, it was at 1/2 when it was empty.

I put my early model gauge into the late model cluster and now it reads over 1/2 when it's full.

I've given up messing with it, and I fill up every 150 or so miles.

[91 318is]

Here's another thing I found. I pulled my buddies 89 cluster apart to look at the fuel gauge part # and it's different then the other 2 gagues I tried.


This one reads:

9 3030 150 80

1 374 822


The other 2 gauges have this same part #1 381 366


So it looks like I have the wrong part number fuel gauge? According to realoem, I'm suppose to have # 1 381 366

[91 318is]

Went back to confirm it's the cluster by plugging my original one back up one for time and reads almost full.

Here's a few things I noticed if it makes a difference.

My original cluster is a VDO, the other 2 are motometer's.

Here's what the motometer sticker on the backside of the cluster says on the cluster I bought for troubleshooting:

616 394 4353

1 394 326

Index 20

12V


Here's what the sticker says on my buddies 89 that works in my car:

616 044 4351

1 394 317

Index 20

12V



Does any of this stuff make sense to anyone? Are these actual part #'s or just production numbers?

I really want to figure out the EXACT cause of the problem, not just say it's cluster related.

[91 318is]

MADE PROGRESS!

I took the cluster out of my buddies 89 M42 and plugged it in and the gauge is reading different then my other one's. The gauge was reading below 1/2. I swapped my coding plug in his cluster to see if that's the problem and it still worked.

So obviously it's cluster related. Now I gotta find out why my cluster is causing the problem. I know it's not the gauge, it's got a new SI board too.

[91 318is]

Cluster should not make a difference according to the schematics in ETM. Try another cluster if it's 100% knowing working good cluster, as it would be the next easiest thing to do. Report back how the gauge works then.

I attached 325i cluster circuit and late model 318i to compare.

I'm gonna take the cluster out the 89 today and try it when I get home, I'll let you know what happens.


I'm confused about the 2 circuits you posted, they're the same except the circles and one sender X'd out.

I'm pretty tired this morning so I may missing something, lol.