kinda ot: 633csi starting help:

[E34 530]

I have an oppurtunity to get a 633csi for dirt cheap but it won't stay running for more than 5 seconds. The guy said the car is getting spark and turns over, and it will run for five seconds and then just die. The car has been sitting for a long time, so I'm thinking it's a fuel delievery problem. Does this sound like maybe a fuel relay or clogged fuel lines?? Thanks for your help, Andrew

[colo525i]

Sounds like something is stuck or not staying on in the fuel system.

My older bro had an old 320i that sat for 6 months before he bought it. At first it would only start with starter fluid. After soaking the fuel pump in e85 and replacing the fuel pump, it still would not fire. Rapping on the fuel distributor got fuel moving and the car ran fine for a 2000 mile trip. the system on the 633 should be similar to that 320's so check those places for fuel flow (crack a hose and see if it sprays) You could also jump the fuel pump relay to see if that is the issue. Maybe bring some starting fluid to test?

[SnakeyesTx]

Sounds like a Mass Air Flow sensor to me. If the car starts and runs for 5 seconds, dies, and you can start it again and the cycle repeats, its getting fuel. It sounds like the MAF is bad and killing spark/fuel signals.

Try to start it, and while it runs, unplug the MAF. If the idle jumps up to say 2000 rpm, but stays running, you've probably found your culprit. Don't drive it with the MAF disconnected though.

[E34 530]

Sounds like a Mass Air Flow sensor to me. If the car starts and runs for 5 seconds, dies, and you can start it again and the cycle repeats, its getting fuel. It sounds like the MAF is bad and killing spark/fuel signals.

Try to start it, and while it runs, unplug the MAF. If the idle jumps up to say 2000 rpm, but stays running, you've probably found your culprit. Don't drive it with the MAF disconnected though.

Yeah, but couldn't there just be some residual fuel that's causing it to start? And yes, he started it about 10 times and the same thing happned, ran for 5 seconds and then died.

[SnakeyesTx]

Well, if the system is bleeding off pressure, it would be hard to start. If it fires right up after stalling, there would be sufficient fuel pressure there then. I think you could figure out a lot just by ear and feel. If it's starting easily from a bump from the key, and it idles smoothly the spark and fuel probably is getting delivered correctly. If its losing spark signal, say from the crank sensor or pick-up coil, it would probably be hard to start until it gets repeated signals after a few seconds of cranking. If its losing fuel pressure somehow, it'd probably have the idle drop and it would sputter itself into stalling.

[E34 530]

Well, if the system is bleeding off pressure, it would be hard to start. If it fires right up after stalling, there would be sufficient fuel pressure there then. I think you could figure out a lot just by ear and feel. If it's starting easily from a bump from the key, and it idles smoothly the spark and fuel probably is getting delivered correctly. If its losing spark signal, say from the crank sensor or pick-up coil, it would probably be hard to start until it gets repeated signals after a few seconds of cranking. If its losing fuel pressure somehow, it'd probably have the idle drop and it would sputter itself into stalling.

Good advice, but I can't check out the car until I come home from college this Tuesday. This thing is quite the POS .

[Paul in NZ]

Good advice, but I can't check out the car until I come home from college this Tuesday. This thing is quite the POS .

sheesh thats a bit harsh...a 633 is gonna be getting on a bit....

[Jon K]

Andrew if you want I could look at it.

Sounds like:

Fuel Pump
Pressure check valve
Idle Valve

In that order of likelihood of being borked

[E34 530]

Andrew if you want I could look at it.

Sounds like:

Fuel Pump
Pressure check valve
Idle Valve

In that order of likelihood of being borked

sent you a message on AIM

[Jon K]

Andrew - I am at dinner right now, will be back in the dorm in about 30 - 45 mins.