e30 fuel level sender

[moots]

My e30 has stalled twice thus far - from running out of fuel.once with my wifey driving (3 months ago) and last weekend,me driving. Looks like the reserve lite ops is intermittent. Seems that on both occasions the reserve light did not illuminate even tho the gauge shows empty.(my q to refuel has alwayz been the light)So last Sunday I removed the fuel level sender from the tank.(i also discovered i do not have a transfer pump but just 1 fuel pump located just forward of the left rear wheel).The sender unit is basically a float sliding on a steel rod with thin wires at the sides for the fuel level signal and at the bottom of it,there is a metal plate that makes contact to complete the reserve light circuit.I just cleaned the contact points by scraping it using a test pen.Reassembled it and hey...last night the light came on(with needle showing near empty) and stayed on (no flickering unlike b4)whilst on the way out for dinner.Hah...happy man I am and costs nothing.Hope this helps some of you keen to DIY...........

 

[jarance]

Originally posted by moots@Jan 4 2005, 12:34 PM
My e30 has stalled twice thus far - from running out of fuel.once with my wifey driving (3 months ago) and last weekend,me driving.
Looks like the reserve lite ops is intermittent.

Seems that on both occasions the reserve light did not illuminate even tho the gauge shows empty.(my q to refuel has alwayz been the light)

So last Sunday I removed the fuel level sender from the tank.(i also discovered i do not have a transfer pump but just 1 fuel pump located just forward of the left rear wheel).The sender unit is basically a float sliding on a steel rod with thin wires at the sides for the fuel level signal and at the bottom of it,there is a metal plate that makes contact to complete the reserve light circuit.I just cleaned the contact points by scraping it using a test pen.Reassembled it and hey...last night the light came on(with needle showing near empty) and stayed on (no flickering unlike b4)whilst on the way out for dinner.Hah...happy man I am and costs nothing.Hope this helps some of you keen to DIY...........

Your e30 want got contact point. My e36 do not have contact point, the alarm for low fuel is actually based on the average reading of the 2 level sensors. The float actually move a needle which convert the resistance to current. based on the current reading, the alarm is triggered.

 

[2cents]

Originally posted by jarance+Jan 5 2005, 04:39 AM-->QUOTE (jarance @ Jan 5 2005, 04:39 AM)

 

[jarance]

(2cents @ Jan 6 2005, 02:18 PM)

Mr.J, r u sayin dat the engineering design of the fuel sensor system in der e36 is better den der ones in der e30? :blink:

Not really, but seem logically yes. In the power station, we use analog and digital input to give alarm and tripping signal. Analog signal are used because the set point are easily adjusted i.e. you can set the low alarm at 10% of the fuel remaining or adjust to 15% if you think that the 10% is too low. Whereas digital signal is fixed and adjustment is quite limited. However, we do use the digital signal as an backup to the analog signal. (just in case the analog signal failed). For important signal, we do use double or triple redundancy backup..

 

[fuelcheckvalve]

jarance,
can u xplain how e36 fuel tank leveling work? its having 2 tank and pump, are they connected using hose or the pump suck independently mean from 1 pump then the other?

 

[jarance]

Originally posted by fuelcheckvalve@Jan 6 2005, 04:12 PM
jarance,
can u xplain how e36 fuel tank leveling work? its having 2 tank and pump, are they connected using hose or the pump suck independently mean from 1 pump then the other?

actually the fuel tank is only one but seperated into two chamber. There is two chambers because the lower section is seperated into half to make way for the exhaust pipe. But the is only true for the lower part of the tank. When the tank is more than 50 % of petrol, there is no seperation between the tank. have a look of the fuel tank of a typical E36 (extract from ETK)

 

[jarance]

jarance,
can u xplain how e36 fuel tank leveling work? its having 2 tank and pump, are they connected using hose or the pump suck independently mean from 1 pump then the other?

actually the fuel tank is only one but seperated into two chamber. There is two chambers because the lower section is seperated into half to make way for the exhaust pipe. But the is only true for the lower part of the tank. When the tank is more than 50 % of petrol, there is no seperation between the tank. have a look of the fuel tank of a typical E36 (extract from ETK) [/b][/quote]
there are two level sensors for the fuel tank. To access, you have to remove the rear seat. There are two black covers for the fuel sensor. On the driver, the fuel pump and 1 level sensor. On the passenger side, there is the second sensor. yes there is a hose that connected both of the level sensor. The hose basically act as an equaliser by siphoning the fuel from one side to the other. hence the pump will always suck and pump from the chamber on the driver side and fuel is drawn from the passenger side by the hose when the fuel level is low..

have a look at the fuel sensor and pump..(extract from ETK)