E36 - fuel gauge problem

[Russie]

Hi automech,

Welcome to BMWCM.

Don't freak out on this. I know it's easy to ask you not to freak out, but in actual fact it's hard not to have that feeling when you suddenly see the needle dropping to empty and the light is on

When you have the chance to open up the fuel pump unit, you may wanna check the condition of the fuel hose, the clips, etc. If they need to be changed, change them ok?

Goodluck...and let us know if you have solved your problem.

Cheers

 

[Russie]

To recap, my fuel sender wire in the fuel pump broke twice this year. After having the wire soldered back, I thought it would have solved the problem at least for some months.

But this morning, the fuel gauge needle dropped to the empty mark again with the light on. The last thing I remembered was that I still have 1/2 tank of fuel so I drove on assuming the wire could have got loose again.

But to my surprise, the fuel gauge meter suddenly rose back to half tank, then it dropped back to empty again, then it rose to 3/4 tank, then dropped again and there was once it rose up to FULL tank but finally back to empty.

Is this cause by the broke fuel sender wire? or could be due to some other failure? Any sifu to comment on this?

Thanks in advance

 

[Fireblade]

To recap, my fuel sender wire in the fuel pump broke twice this year. After having the wire soldered back, I thought it would have solved the problem at least for some months.

But this morning, the fuel gauge needle dropped to the empty mark again with the light on. The last thing I remembered was that I still have 1/2 tank of fuel so I drove on assuming the wire could have got loose again.

But to my surprise, the fuel gauge meter suddenly rose back to half tank, then it dropped back to empty again, then it rose to 3/4 tank, then dropped again and there was once it rose up to FULL tank but finally back to empty.

Is this cause by the broke fuel sender wire? or could be due to some other failure? Any sifu to comment on this?

Thanks in advance

Sounds like your fuel sender unit is faulty as it is giving erratic signal to the fuel gauge. Check the wiring first before changing any parts.

 

[jarance]

First check the resistance of both the level transmitter with a ohms meter. You can easily buy a analog type for about RM40 to 50. The resistance should be from
10 ohms to about 150 ohms depending on the amount of fuel in the tank.

Tank full = 10 ohms
Tank empty = 150 ohms.

If the resistance is within the range then it is not the fuel sender (level transmitter) problem. It could be the fuel gauge.

based on my experience, it is usually the fuel sender due to wire coming off when you go over a bump.

I have solve the problem by removing the original cable and resolder with a wire that is resistance to petrol and longer to allow the fuel pump to move free without letting the cables becoming taunt when it is pull.

 

[Russie]

thanks for all input. Jarance, are u in klang this week or in PD? Any chance of you helping me out on this DIY thing? appreciate your reply.

thanks

 

[jarance]

Weekday - in PD.

Go back to klang around 5pm on Saturday.

Free on Monday (Public Holiday).. If you like, this Monday can DIY at house in Klang..

BTW, don't pump your car to full tank when you come cos you will loose it when you open the fuel sender.

 

[Russie]

Weekday - in PD.

Go back to klang around 5pm on Saturday.

Free on Monday (Public Holiday).. If you like, this Monday can DIY at house in Klang..

BTW, don't pump your car to full tank when you come cos you will loose it when you open the fuel sender.

Thanks for your help jarance. But do I need to purchase any petrol-proof wire or anything? I have no idea what to do at all. Pls advise.
Will SMS u

Thanks

 

[jarance]

No need to purchase the wire.. I have spare available.

 

[Russie]

Today, 1 September 2008, a public holiday and I got my fuel sender wire problem fixed. Thanks to Jarance for his very kind help :top: It appears that the fuel sender wire broke again since the last time I got it soldered back.
Will post some pictures soon as to contribute to sharing.

To be continued...

 

[infinityKL]

glad to hear... thx fr sharing, important knowledge for E36'ers...

 

[Russie]

As promised, some pictures for the knowledge of fella E36'ers:

1) This is how the fuel gauge meter looks like as the fuel sender wire is broke (sorry for the dusty dashboard no time to wipe)

2) Using a light-duty hammer, hammering off the damper rubber

3) The ohm meter used to check the resistance of the wire (to determine which wire is broke)

4) Finally, taking out the fuel pump unit

5) Fuel pump being taken out

6) Notice the black wire which was disconnected from the sensor unit?

7) The cause for the wire to break/ disconnect was mainly due to insufficient buffer length in the wire, causing it to break and disconnect when going over bumpy or uneven road surface. So Jarance replaced the broken wire (black) with a longer wire (yellow) and soldered it back

8) Soldering in process...

9) The yellow wire (replacement wire) which is relatively longer than the original wire

10) Found that the 2 small damper rubber have worn out too... So slotted in a piece of sound dampening material and tied them back using some copper wire

11) The new wire (yellow) nicely soldered

12) Another view at both ends for the yellow wire

13) Final test on the resistance before installing back the fuel pump unit

14) Installed back the fuel pump unit

15) Finally, it's done (notice the few drops of sweat? Thanks Jarance for the help...appreciate it much)

Thanks for viewing guys, hope this helps in a way for those who wanna DIY in this matter.

 

[jarance]

Russie, just notice that the plastic hose from the fuel pump is slightly damaged. Thought it was due to my soldering work but actually was caused by the previous guy who did the repair.

Thanks for the pictures..

 

[Fireblade]

Russie, just notice that the plastic hose from the fuel pump is slightly damaged. Thought it was due to my soldering work but actually was caused by the previous guy who did the repair.

Thanks for the pictures..

Yeah, noticed that too. Good job Jarance- well done. When I changed my fuel pump a couple of months ago I noticed that both the rubber dampers had disintegrated too. I believe my fuel pump has never been changed since the car was new (1994). BTW my fuel pump had the white casing (325i).

 

[jarance]

fireblade, I think it the year of maunfacturing. Mine is also 1994 and the top casing is also white in colour.

If you observed carefully, there is one less hose coming back from the other "tank".

 

[Russie]

Russie, just notice that the plastic hose from the fuel pump is slightly damaged. Thought it was due to my soldering work but actually was caused by the previous guy who did the repair.

Thanks for the pictures..

Yup, the plastic hose was damaged during the repair work previously coz I was busy chit chatting with the mechanic and he accidentally moved the solder gun to the hose. But luckily, it is only minor damage and no hole in the hose.

Thank you

 

[Fireblade]

Yeah, noticed that too. Good job Jarance- well done. When I changed my fuel pump a couple of months ago I noticed that both the rubber dampers had disintegrated too. I believe my fuel pump has never been changed since the car was new (1994). BTW my fuel pump had the white casing (325i).

Guess what..... yesterday my fuel gauge went dead and the reserve light came on. At first i suspected that I might have a leaking tank but the floor was clean. So next I suspected it could be one of the float sensors. First checked the left one and it was showing 150 ohms (had slightly more than 3/4 petrol in tank) - seems OK. Then checked the right one - open circiut (no reading). Damn, I just changed this fuel pump (c/w float sensor) a few months ago. My mech opened it up and found one sensor wire detached (broke off from terminal). Seems that the manufacturer over crimped the pin and caused the wire to be partially broken - finally broke away this time. Could not solder the wire to the pin as solder does not stick to the pin. So took a metal tube connector, soldered the wire to this and inserted the tube into the pin. Viola - got connection and tested resistance. At full height (i.e. full tank condition) the resistance was 250 ohms- as per specs. Cant imagine having to spend another RM400 on a new unit if I did not discover this simple fault.

 

[bmyotaE36jz]

Hi guys.

Sorry for bringing up this old topic. But I have an issue on my E36 318i fuel gauge.

My case is different. The tank went dry before the fuel gauge warning light even light up. Slightly below the 2nd to last line then walah, car cough and stopped.

Any suggestion sifus out there.

Thanks very much.

 

[jarance]

Hi guys.

Sorry for bringing up this old topic. But I have an issue on my E36 318i fuel gauge.

My case is different. The tank went dry before the fuel gauge warning light even light up. Slightly below the 2nd to last line then walah, car cough and stopped.

Any suggestion sifus out there.

Thanks very much.

Could be a faulty fuel sender or a faulty fuel pump if there is petrol still left in the tank.

You can check the fuel pump condition by checking the pressure at the fuel rail.

 

[bmyotaE36jz]

Could be a faulty fuel sender or a faulty fuel pump if there is petrol still left in the tank.

You can check the fuel pump condition by checking the pressure at the fuel rail.

Thanks brother jarance.

Nope. It is completely empty and the fuel gauge still shows 1 bar of fuel.

Thanks again brother jarance.

 

[jarance]

Thanks brother jarance.

Nope. It is completely empty and the fuel gauge still shows 1 bar of fuel.

Thanks again brother jarance.

Have a look at Alex posting. Your problem is similar to his. - worn out contact point.
http://www.bmwclubmalaysia.com/foru...nit-Right-side&p=692607&viewfull=1#post692607