Fuel Gremlins: I think I have one.....

[Jdesign]

So, this has happened a few times, but not in awhile. Previously, I figured out that the problem was a loose fuel line clamp on the top of my fuel tank under the back seat. If I park on just the right angle or slope, my car would have a difficult time firing. It would turn over fine, but just keep cranking with a little sputter here and there. If I would wait a minute or two and try again, sooner or later it would fire, and once it was running, it would be fine.

I fixed the fuel line and haven't had a problem since.....SINCE today. I was pretty low on fuel and when I started my car this morning, it took a few extra cranks to fire. I thought maybe is was because my car was on E. So I drove to the gas station, shut it off and filled it up. Got back in, crank it and a few sputters and nothing. Awesome.

So I sat there for a few minutes. My car was at that perfect slope at the pump. Crap. So I tried again and it fired a little more but then died and showed no further signs of firing. So I sat there and thought to myself thinking; did my fuel pump just die? Well what else is there?

FUEL

-Relay -OEM

-Pump -OEM (I think)

-Filter -New

SPARK

-plugs -New

-wires -Old as shit

-cap/rotor -New

So I got out, pulled the relay for the FP out and cleaned it off with what I had. ( a towel ) I put it back in, and tried again. The car cranked and slightly fired. I stopped, pumped the gas while cranking again, fired right up. So....

I assume the relay is bad, but can anyone confirm this is my actual problem? Or could it actually be the pump, and for some reason the time it sat there while I cleaned the relay allowed it to work again? I have a new pump and I will be buying a new relay regardless.

[patsbimmer1]

I'd go with pump.  If it keeps start and killing then I would assume the relay is powering the pump but the pump is failing and not completely dead. You can check the relay with a multimeter if you have one with relative ease.  2 poles will read near zero Ohms and the other 2 will read a specified amount based on what it is rated for.  If the open position has resistance then it is bad and if the closed position reads 0 or low ohms then it's bad.

[Jdesign]

I intend on replacing both so I am not too worried. I will test it though.

On the other hand, I was more curious if anyone would think is could be something else. Last time something like this kept happening is was my Crank Position Sensor.

[tsweers89]

Replace the pump. Filter and relay. End of story. On to the next cappy part that is going to fail on a e30. If they have never been replaced under your ownership why not do it for peace of mind anyways?

[Jdesign]

tsweers89 said:

Replace the pump. Filter and relay. End of story. On to the next cappy part that is going to fail on a e30. If they have never been replaced under your ownership why not do it for peace of mind anyways?

So I just replaced all of it. Pump and relay. The filter was replaced last year. Have the car sitting at the "hard to start angle" and the problem still persists. It starts up, but I can tell there is still an issue. It's almost like it chokes slightly then fires. I keep starting it and shutting it off repetitively and sometimes it just cranks and won't fire. Other times it turns over right away. Could it be the ignition switch?

[straight6pwr]

so you are saying if the car is not parked at this weird angle it will start fine 100% of the time?

have you thoroughly tested this theory or just notice that when it doesnt start it seems to be at 'the hard to start angle'?

it sounds like a red herring to me.

is the car running 100% OK once it gets going?

[Jdesign]

straight6pwr said:

so you are saying if the car is not parked at this weird angle it will start fine 100% of the time?

have you thoroughly tested this theory or just notice that when it doesnt start it seems to be at 'the hard to start angle'?

it sounds like a red herring to me.

is the car running 100% OK once it gets going?

I just noticed that most of the time its more difficult at this angle. Could just be an illusion too. I just recently replaced a bunch of things to try and solve the issue.

FUEL

-Relay -New!

-Pump -New! 

-Filter -1 year old

SPARK

-plugs -New

-wires -Old as shit

-cap/rotor -New

SENSORS

-Crank position sensor- New to this car, but USED. I replaced this last year when I was having random no start issues. Could it be the problem again?

-O2 sensor-NEW

I haven't really had the issue after changing the pump, fuel relay, O2 sensor, and spark plugs a few weeks ago. I drove all the way to SOWO (over 1700 miles) and back without issue. The car has been running great, smooth idle and power band, until now. It seems to be having a similar problem as before. Randomly wont start, or starts after a few tries. Doesn't matter if its hot or cold. I also noticed that it if its idling, and I try to quickly tap the gas, it coughs then revs. Almost seems like the timing is off, but it wasn't off before? I also checked the plugs and they seem to have the symptoms of running slightly rich..again.

Any ideas or help would be appreciated.

[YoungCR]

Check your cap and rotor, I just cured my "lean" issues with that.

[Jdesign]

CYoung said:

Check your cap and rotor, I just cured my "lean" issues with that.

Its new...

[YoungCR]

I forgot to as the part where Merl got a bad cap from the factory, he found that out by checking the resistance.

[Boris3]

Check the clamp again that fixed it last time?

Test your angle theory. Find the angle and see if it starts. If not roll it to a slightly different position and try to restart.

Ecu on the way out, wiring loose/worn? Fuseable link on small wire from battery to ecu shorting out? Fuel pump fuse?

Any relation to level of fuel in the tank? Gas station matter?

Any relation to weather, temp changes, rain, could be condensation in tank etc... throw in a bottle of fuel line dryer.

Hoses, vacuum leaks, temp sensors, wiring that would cause car to run rich.

Age/mileage on the timing belt, plug wires, coil?

[tsweers89]

How about you get a fuel pressure Guage on it and start doing some diagnosis and not just throwing parts at it? Find some reason we're this occurs and make it happen while looking at the Guage to make sure pressure is up to party and not leaking down or such.

[Jdesign]

CYoung said:

I forgot to as the part where Merl got a bad cap from the factory, he found that out by checking the resistance.

This is interesting. Was it variable? I will check it, but the car ran fine when I put new plugs in it, and it ran fine when I replaced this last year.

Boris3 said:

Check the clamp again that fixed it last time?

Test your angle theory. Find the angle and see if it starts. If not roll it to a slightly different position and try to restart.

Ecu on the way out, wiring loose/worn? Fuseable link on small wire from battery to ecu shorting out? Fuel pump fuse?

Any relation to level of fuel in the tank? Gas station matter?

Any relation to weather, temp changes, rain, could be condensation in tank etc... throw in a bottle of fuel line dryer.

Hoses, vacuum leaks, temp sensors, wiring that would cause car to run rich.

Age/mileage on the timing belt, plug wires, coil?

I replaced that clamp, and I checked it, I actually replaced the one next to it too!

Angle theory is a myth, I think it was more true when that clamp was bad which makes more sense.

ECU could be the issue(I hope not though)

Fusable link is a good one, but I also checked those

Fuel pump fuses and and relays have all been replaced

I never tried with different amounts of fuel, but Its happened on empty and fully topped off tanks

Gas station doesnt matter

Fuel line dryer inst a bad idea either. Although I just ran injector cleaner through it exactly one month ago

Temperature doesn't matter, as its stored indoors and has happened sitting in my shop and outside (variable from 40-80 degrees F) 

My next move is to check hoses, vacuum leaks, and MOST IMPORTANTLY the temp sensors, I read that they can cause the car to run extremely rich if they are old(which I assume mine are original)

Age/mileage on the timing belt isd about one year ago.

Plug wires are pretty much garbage

I never replaced the coil, but tested it last year and the output resistance was good. I will check it again.

tsweers89 said:

How about you get a fuel pressure Guage on it and start doing some diagnosis and not just throwing parts at it? Find some reason we're this occurs and make it happen while looking at the Guage to make sure pressure is up to party and not leaking down or such.

This is a great idea. I think I have a spare gauge for my dinosaur civic build BNIB. I will try this, but I know its getting fuel, maybe even too much.

[Schwabenlander]

I not sure if you are still having issues. As for the hard to start angle I think I have an idea. I know all of the modern BMWs have a saddle type fuel tank to accommodate the driveshaft. This means that there is one fuel pump and also a siphon pump to transfer fuel from the side without a pump to the side with the pump. I was thinking maybe if you parked on a specific angle where the fuel pooled to the side with the siphon pump it has no way to deliver it to the pump side. I'm not familiar with e30s however and don't know if the saddle type gas tank goes back that far.