fuel related 91 325i

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#1
hey guys
my friends 91 325i has two fuels pumps under the rear seat. one on the passenger and one on the driver. they both have a big fuel line that comes towards the middle and a smaller one that goes directly down and towards the motor.
a. does anyone know which one is the feed and which ones are the return?

b. does anyone know which one if not both are supposed to prime and what kind of noise they are supposed to make when priming and.....

c. is there a way to test the ignition system?


thanks for the time guys. please help me out here.
 
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fort collins, colorado
#2
you have two access panels under your rear seat but only one is a fuel pump

the one on the drivers side covers your fuel level sensor and the one on the passenger side is the fuel pump
 
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Bay Of Islands, NZ
#3
The fuel level sender shouldn't have a fuel line going to it - just a wiring connector.

Easiest way to locate the return is follow the two fuel lines under the car. The fuel filter is on the supply line, the other is the return.
 
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#4
i don't know dude, they both have identical lines and them. both also have sensors, i talked to a bmw mechanic and he said the driver side pump is external (not in the actual gas tank) and supplies pressure when the engine needs more fuel (flooring it and what not). anyone know how to check fuel pressure on one of these?
 
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#6
you got if bro. when taking off the smaller line on the driver side (fuel pump) small amounts of gas came out. i am assuming that there should be much more than that (supposedly good fuel pressure is 41 psi) does anyone know a way to check it.
 
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Australia
#8
Ok... I've said this many times, The pump under your seat primes the entire fuel system (including the external fuel pump) ready for engine start.

Park somewhere quite and switch the key from off to ignition (not start) you will hear a slight 2 - 4 second buzz.

If you don't hear the buzz, expect electrical hastles (power to pump), pump failure of even a blockage in the little wire gauze within the unit. You can clean it.

Always search before asking a question, as this particular question has been answered many times.
 
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Location
the woodlands
#9
Ok... I've said this many times, The pump under your seat primes the entire fuel system (including the external fuel pump) ready for engine start.

Park somewhere quite and switch the key from off to ignition (not start) you will hear a slight 2 - 4 second buzz.

If you don't hear the buzz, expect electrical hastles (power to pump), pump failure of even a blockage in the little wire gauze within the unit. You can clean it.

Always search before asking a question, as this particular question has been answered many times.
wow, you don't think i know that already. everyone i talk to tells me something different. so its hard to come to a conclusion. i posted on here because i am not familiar with how bmw's fuel system works. so far you have been the only useless one on here so i would keep to the for sale forums if i were you.
 
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#11
wow, you don't think i know that already. everyone i talk to tells me something different. so its hard to come to a conclusion. i posted on here because i am not familiar with how bmw's fuel system works. so far you have been the only useless one on here so i would keep to the for sale forums if i were you.
I answered question "b." and gave advice... What else have people been telling you about the e30's fuel system?

Ignorance.
 


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