E30 Fuel Problem

[Idrisu]

***1989 325is***
Got the car not too long ago and ran into a fuel problem. Since the gas gauge doesn't work the previous owner told me that once I hit 300 miles, that is when I would need to fill up. A couple of days go by and I hit 300 miles. Arriving at my local gas station I start putting gas in and about $2 in, the fuel handle stops putting gas in indicating that my tank is full. Being confused as to why it stopped I kept trying to put more. Gas started overfilling and spilled out from the mouth of where you put the gas in. I took it to my local BMW shop and they suspected it was the charcoal canister but looking into it they eliminated that idea. Surprisingly they told me I had a full tank of gas and I was confused as hell as to why I had a full tank of gas after traveing 300 miles. They told me I had a bad fuel sending unit or level sender, something along those lines. I don't see how that would affect gas comming into the tank. Any ideas what could be wrong? I'm not spotting any leaks or puddles on the ground or engine bay.

[noid]

Fix the gauge/fuel sender, then fill up when low.

[itsonlygeorge]

Surprisingly they told me I had a full tank of gas and I was confused as hell as to why I had a full tank of gas after traveling 300 miles.

Clearly your car runs on rainbows and pixie dust.

[lambo]

One note for filling your e30 up with fuel: Don't insert the nozzle all the way. Insert it only 50-75% of the way. Maybe it's just me, but if I insert it as far as it will go, the pressure doesn't seem to release correctly and it will trick the pump into thinking the tank is full when it is not.

[Idrisu]

One note for filling your e30 up with fuel: Don't insert the nozzle all the way. Insert it only 50-75% of the way. Maybe it's just me, but if I insert it as far as it will go, the pressure doesn't seem to release correctly and it will trick the pump into thinking the tank is full when it is not.

I've tried that method already. Does the same thing and overfills much quicker.

[Idrisu]

Fix the gauge/fuel sender, then fill up when low.

How does that affect how gas enters the car and from overfilling?

[noid]

How does that affect how gas enters the car and from overfilling?

How do you know how much fuel you have in the tanks? Because it "overfilled"? How do you know there isnt an obstruction partial or full in the filler hose, or the cross over tube?

Check how much fuel you have by removing your rear bench and looking through he fuel pump access hole; but remember while your in there, fix your level sender (if broken).

[Idrisu]

How do you know how much fuel you have in the tanks? Because it "overfilled"? How do you know there isnt an obstruction partial or full in the filler hose, or the cross over tube?

Check how much fuel you have by removing your rear bench and looking through he fuel pump access hole; but remember while your in there, fix your level sender (if broken).

the hose that connects the metal filler neck to the passenger side tank is squishy but there isn't and leaks coming from it. when the filler neck is full and I squeeze this hose you can see the fuel left in the mouth bubble.

[itsonlygeorge]

Replace that hose then? It might have started coming apart on the inside?

The crossover tube can be removed on early model tanks and cleaned with pipe cleaner or replaced with new.


Crossover tube is #4 on early model tank.

I think on the new model tanks the crossover tube is internal and could be clogged or rusted. What is the condition of the inside of the tank? Is it rusty? If one side of your tank is full and the other is not, the crossover connection might be clogged. It could also be due to a weak fuel pump or clogged filter.

"Fuel is transferred from one side to the fuel pump side by a jet action pump. Fuel being returned by the fuel pressure regulator draws the fuel from the left side of the tank through an orifice, using a venturi effect, so no mechanical pump is necessary. The fuel is directed to the right side tank and is picked up by the electrical fuel pump."

That would make your fuel sender think your tank is empty and you would be trying to fill up the other side that is full. Late model tank has two fuel level senders:



Senders are part #5 and #9.

It could also be other fuel system hoses or part of the evaporative system.

[Idrisu]

Replace that hose then? It might have started coming apart on the inside?

The crossover tube can be removed on early model tanks and cleaned with pipe cleaner or replaced with new.


Crossover tube is #4 on early model tank.

I think on the new model tanks the crossover tube is internal and could be clogged or rusted. What is the condition of the inside of the tank? Is it rusty? If one side of your tank is full and the other is not, the crossover connection might be clogged. It could also be due to a weak fuel pump or clogged filter.



That would make your fuel sender think your tank is empty and you would be trying to fill up the other side that is full. Late model tank has two fuel level senders:



Senders are part #5 and #9.

It could also be other fuel system hoses or part of the evaporative system.

what do you think about the purge valve or the charcoal cannister? I changed the fuel filter and it was full of gas and the hose were leaking when i took it out

[itsonlygeorge]

I am not sure about that line of reasoning. I know the charcoal canister is in the engine bay, and the purge valve is probably close as it controls how much vapor is purged TO the charcoal canister, which is basically a filter to the outside.

I am be no means an expert on the evaporative fuel system as this is part of the Evaporative Emission Control (EVAP) system, for emissions. I did a quick search and came up with this.

http://www.samarins.com/glossary/purge-valve.html

Like I said before, I think it is a problem with your gas tank. Those metal lines that help fuel flow from one side of the than to the other may be clogged, or your fuel pump maybe weak or the fuel pump filter may be clogged with sediment or rust.

Have you opened up the access hatch and taken the pump out to assess its condition and peek inside the tank? Is there rust in there? That's what I would check.

The evaporative system is in the passenger wheel well and can be accessed by removing the plastic panel. Remove the tire and check behind part #21 to see the wires/hoses back there. I would try to trace down hose #5 and see if its leaking or corroded. That hose is probably a vent to the fuel filler line.

I honestly think that chasing down the evap system is a waste of time before you check the more obvious problems with the fuel pump or tank. If it's rusty in there thats probably the root cause of your issue. If you have the 2 fuel senders, take both out with the fuel pump and take a look at the level in both sides of the tank. If they are different (and one side is full) there's probably a problem with the tank.

[Idrisu]

I am not sure about that line of reasoning. I know the charcoal canister is in the engine bay, and the purge valve is probably close as it controls how much vapor is purged TO the charcoal canister, which is basically a filter to the outside.

I am be no means an expert on the evaporative fuel system as this is part of the Evaporative Emission Control (EVAP) system, for emissions. I did a quick search and came up with this.

http://www.samarins.com/glossary/purge-valve.html

Like I said before, I think it is a problem with your gas tank. Those metal lines that help fuel flow from one side of the than to the other may be clogged, or your fuel pump maybe weak or the fuel pump filter may be clogged with sediment or rust.

Have you opened up the access hatch and taken the pump out to assess its condition and peek inside the tank? Is there rust in there? That's what I would check.

The evaporative system is in the passenger wheel well and can be accessed by removing the plastic panel. Remove the tire and check behind part #21 to see the wires/hoses back there. I would try to trace down hose #5 and see if its leaking or corroded. That hose is probably a vent to the fuel filler line.

I honestly think that chasing down the evap system is a waste of time before you check the more obvious problems with the fuel pump or tank. If it's rusty in there thats probably the root cause of your issue. If you have the 2 fuel senders, take both out with the fuel pump and take a look at the level in both sides of the tank. If they are different (and one side is full) there's probably a problem with the tank.

Okay I took the #21 panel off and it looks like the hose with the arrow pointed at it is #5.




I then removed the fuel pump/level sender and it seemed to be full. Gas was streaming out of it fast.



I then went to the driver side level sender it that also was fuel.



At this point I don't think anything is causing it to overfill quickly now. Should I go ahead and replace the passenger fuel pump/level sender and the driver side level sender?

[itsonlygeorge]

I would disconnect the hoses to the fuel pump and take it out to take a look. You will need to take the fuel level sender out as you already have before you take the pump out. Its pretty easy.

Once you have the pump out take a look at the filter. If it looks all cruddy and has lost of rust or sediment discoloration your tank is probably rusty inside and is causing the fuel pump to fail.

Take a flash light and shine it inside the tank. Look for rust, debris, etc.

My guess is that the fuel pump is bad and there is probably rust in the tank. You've already done the hard part of taking the pump out so take a look in there! Don't run the pump outside of the gas, it will fail as the gas lubricates it.

If the tanks rusty, I would replace it. Not a fun job but it's doable with a friend. I did mine last fall and it took about a day. You will need to drain the tank using the drain plug. New Spectra tank is like $200 and will not have a plug.

1. Drop exhaust and remove heat shields
2. Drop drive shaft - check guibo and CSB, replace as necessary if rubber is torn or cracked (4 bolts on diff side, 2 for CSB, 3 for guibo if its in good shape, if you need to replace it you will need to take out all 6 and make sure to align the arrows on the guibo so the point towards the metal flange
3. Remove fuel pump + senders
4. disconnect fuel filler hose, (replace if its cracked or worn or mushy) and depressurie fuel system (disconnect fuel filter line)
5. there are 6 bolts that hold the tank in place, once you remove those you just have to wiggle it out
6. put it back together in reverse order

[Idrisu]

I would disconnect the hoses to the fuel pump and take it out to take a look. You will need to take the fuel level sender out as you already have before you take the pump out. Its pretty easy.

Once you have the pump out take a look at the filter. If it looks all cruddy and has lost of rust or sediment discoloration your tank is probably rusty inside and is causing the fuel pump to fail.

Take a flash light and shine it inside the tank. Look for rust, debris, etc.

My guess is that the fuel pump is bad and there is probably rust in the tank. You've already done the hard part of taking the pump out so take a look in there! Don't run the pump outside of the gas, it will fail as the gas lubricates it.

If the tanks rusty, I would replace it. Not a fun job but it's doable with a friend. I did mine last fall and it took about a day. You will need to drain the tank using the drain plug. New Spectra tank is like $200 and will not have a plug.

1. Drop exhaust and remove heat shields
2. Drop drive shaft - check guibo and CSB, replace as necessary if rubber is torn or cracked (4 bolts on diff side, 2 for CSB, 3 for guibo if its in good shape, if you need to replace it you will need to take out all 6 and make sure to align the arrows on the guibo so the point towards the metal flange
3. Remove fuel pump + senders
4. disconnect fuel filler hose, (replace if its cracked or worn or mushy) and depressurie fuel system (disconnect fuel filter line)
5. there are 6 bolts that hold the tank in place, once you remove those you just have to wiggle it out
6. put it back together in reverse order

I tried looking into the tank but it was hard because of the reflection. I haven't tried it with the flashlight though. I ordered a fuel pump so when it comes I'll take another look with a flashlight. And you said take a look at the fuel pump 'filter'? Is that the cylinder object in the assembly?

[itsonlygeorge]

The cylinder is the pump motor. The filter is the white "sock" that sticks out like an L. It is the inlet for fuel. It basically sits at the bottom of the tank in a splash cup and is where fuel enters the pump. If it becomes clogged the fuel pump will burn out because the gasoline acts as a lubricant for the pump motor and mechanism.

That's why I suggested you take the pump out and look at the filter. If its covered in sediment and the filter is clogged then the pump will burn out. Once you look in the tank with a light you should be able to see what the inside of the tank looks like. If there is a lot of rust, then a new pump won't last very long as there is a good chance the filter will clog up and the motor will burn out.

Do you have a Bentley Manual? There is a whole section on testing fuel delivery. You should go through it before replacing the old fuel pump to establish a baseline measurement. See if the old pump has below average fuel delivery, look at the color of the fuel, rule out some variables before you blindly replace parts and try to understand what is going on with the car with actual data.




Rusty Tank:


Look at post #375

http://www.r3vlimited.com/board/showthread.php?t=191125&page=25