[bakocom]

The BMW coupe has ran perfectly for 2 years. I can shot a bunch of starter fluid down into the intake and get the car started, I have to hit the gas padel while I'm doing that and get the car revving! Then it will drive fine I can turn it on and off all day but if I let it sit for 24 hours it won't start again. Does anyone have any idea what that could be?

[E92_William]

Sounds like a fuel issue then if you're having it start with starter fluid. What if you when you first get in the car and put the key in the ignition, turn on the ignition but without pressing the brake pedal and just let it sit there for like 30 seconds maybe. Also good to pop the gas cap and maybe you can hear the pump running. Might be losing fuel pressure overnight

[bakocom]

I just tried letting it sit for 30 seconds and the gas cap off, almost started a little bit but I didn't have my foot there to stomp the gas peddle! It's weird this all started a month ago, at first it was once a week it wouldn't start right up. The other day it just didn't start at all so I used the starter fluid to get it running. The car ran all day and left it for a day yesterday and now it won't start again so the problem is getting worse.

[TunafishE93]

Sounds like your fuel pump is going out, you should be getting codes if that is the case..

[bakocom]

TunafishE93, That is what is weird too there is no check engine light on. I just don't want to start installing new parts not knowing if there broke. The car has 135,000 miles seems like not that many miles to need a new fuel pump yet? I guess I will take off the covers under the car and check the fuel lines to see if there is anything wrong with them.

[TunafishE93]

The fuel pump likely won't throw a check engine light but will be there when scanned. I just went thru this but with a n55 (I know different pump/engine) and I had low pressure codes but no check engine light.

[F31B48]

N52 engine doesn't have a fuel pressure sensor, so it won't store any fault codes if the pressure is low. You'll need to check the fuel pressure with a guage. Should be about 5 bar or 70psi.

[bakocom]

Hi EvaBmw, I think my engine is the N51 I have been reading stuff all night long. I live in California so I'm pretty sure I have the more complicated gas tank with all the environmental stuff to keep the air clean. I have a few tests I am going to try tomorrow on the fuel pump to make sure it is coming on properly when I try to start the car.

[F31B48]

N51 doesn't have a fuel pressure sensor either. Only the direct injection engines have it. n53, n54, n55.
Isn't there some sort of BMW extended warranty for the n51 in California? I think there may be a thread about it on here somewhere.

There is a pressure testing valve on the fuel rail that you can attach the pressure guage to.

[bakocom]

Okay, maybe the fuel pump is broken? I wired a 12v battery to it. I connect the positive to the + and negative to the - on the fuel pump and I don't get anything happening at all. I am pretty sure I connected it to the right terminals I took some pics can anyone verify they are right? Is this the right way to get the fuel pump started or did I hook it up wrong?

[TunafishE93]

You will have to get a close up of the plug to be able to tell

[bakocom]

Every other BMW fuel pump is simple with a 2 wire plug but this one has 6 wires! I took the resistance of the pins too and the pump pins look to be an open circuit.

[bakocom]

Didn't hit the pic upload button here they are!

[TunafishE93]

They look to be correct but not sure if there is a signal wire to turn on the pump. The pump/plug is for the n51 which are different from others. ISTA had the plug in there but couldn't find info on the other pins. Might be in emission but didn't look.

[F31B48]

Pin 5 and 6 are the fuel pump wires

[bakocom]

Thanks, TunafishE93 and EvaBmw! I got a fuel pump on the way. My fuel pump must be broke, the car started right up yesterday and I drove it around and everything and tested the pin 5 and 6 and it was 10 ohms. This morning it still had resistance and would start but now that it's 110 out here!! The circuit is open again. It's just too dam hot here!! haha I am sure a new pump will fix it up I will let you know.

[bakocom]

Okay, I fixed it! Why didn't you guys tell me a fuel pump was so hard to remove!! Every little part has a trick on how to take it off and then a different trick to put it back on. After putting it all together and I go to start my car its starts then sputters off. I was just like why did I try to do this? lol. I knew I screwed up and had to take it back apart because I didn't clip the fuel line on properly and it popped off in the gas tank! There is a little tiny hole on the fuel line that you need to poke in, to reengage the clip, I had to make a tool to reach all the way down in the tank to do that. I found the real problem too since the old fuel pump wasn't broke the red positive connector(that plugs into the pump) was being dissolved by the gas! I took some pictures to show you guys but that is why it worked some times and not other times. I am so lucky the car never stopped on me while I was driving. Anyway, it's fixed and the whole problem could have been fixed with a new $1 connector haha.

[bakocom]

Here are the pics