Fuel filter?

[7thDimension]

When I start my car after it's been sitting all night (when it's cold), it cranks for a few seconds before it fires. All of our other vehicles, including my mom's e39 start literally on the first crank every morning. Even when it's warm, it doesn't start up as quick as I think it should, kind of like starting a carbed vehicle if you know what I mean. I cleaned the maf and changed the air filter a couple months ago. Could it be the fuel filter? My car has 270k miles, and as far as I know, the fuel filter is original. Is it normal for these cars (m62) to crank for a bit before they start?

[M I C H A E L]

nah it should start right up.. and if you dont know when the fuel filter was last changed, id say go for it. and give it a seafoam too while ur at it.

[7thDimension]

I seafoamed it shortly after I cleaned the maf, so I guess I'll try fuel filter. Funny thing is that it runs perfect, it'll spin the tires easy in sport mode, and it pulls great through redline. It has new plugs, coils are original, and as far as I know the injectors, fuel pump, regulator, etc are original, I have no cel or codes.

[E38bimmer]

Is it throwing any codes with it running like that im sure the CEL is on

[7thDimension]

Is it throwing any codes with it running like that im sure the CEL is on


Funny thing is that it runs perfect...I have no cel or codes.

Any other ideas?

[M I C H A E L]

replace coils and fuel filter. go from there.

[Timm]

The fuel pump has a one-way valve which stops the fuel returning to the tank when the engine is not running. If this valve leaks, the fuel-rail pressure drops when the engine is off - the next time you try to start the engine, the pump has to replenish the fuel in the fuel lines and fuel-rail - and then build up pressure.

Easy to check as described here:

http://www.meeknet.co.uk/E38/Fuel-rail-pressure.pdf

[7thDimension]

The fuel pump has a one-way valve which stops the fuel returning to the tank when the engine is not running. If this valve leaks, the fuel-rail pressure drops when the engine is off - the next time you try to start the engine, the pump has to replenish the fuel in the fuel lines and fuel-rail - and then build up pressure.

Easy to check as described here:

http://www.meeknet.co.uk/E38/Fuel-rail-pressure.pdf
Ok, I'll check that, thanks.



replace coils and fuel filter. go from there.
It isn't misfiring, should I replace the coils anyway? Do they normally go bad over time?

[David325e]

Not sure why I haven't seen it mentioned. But What if you have a fuel leak that is causing a pressure drop?

I'd be interested to see pressure drop at the fuel rail when the car is sitting. Possibly a bad FPR allowing fuel to leak back. Or what kind of mpg's are you getting? Possibly a pissy injector. Not bad enough for dieseling, but maybe a drop in mileage and losing pressure while sitting. A cheap way to tell- any of your spark plugs blacker than the others?

[7thDimension]

Not sure why I haven't seen it mentioned. But What if you have a fuel leak that is causing a pressure drop?

I'd be interested to see pressure drop at the fuel rail when the car is sitting. Possibly a bad FPR allowing fuel to leak back. Or what kind of mpg's are you getting? Possibly a pissy injector. Not bad enough for dieseling, but maybe a drop in mileage and losing pressure while sitting. A cheap way to tell- any of your spark plugs blacker than the others?

Spark plugs look fine, obc shows ~11mpg all city driving. I know my o2 sensors need to be replaced, so I think that may be the cause of my horrendously poor mileage, but it could very well be a leaky injector. It smells like gas around the engine compartment on a cold start, it also starts kind of rough sometimes. No visible leaks, compression is perfect, doesn't burn any oil. What do you think?

[M I C H A E L]

Well if you don't think the coils have ever been replaced, i would replace them. that's alot of miles on old coils... so Yes..

Second.. Do you smell fuel under your hood? or any fuel leaking anywhere?

11mpg city.. yeah... you should be getting atleast 17-19

[David325e]

Coils can be tested before you start throwing parts. That's a big chunk of change. You need to hand calculate the mileage.

Park over a white sheet and see what color leaks you get from where. I still think you have a fuel leak somewhere causing a drop.

[M I C H A E L]

check your filler hose too.

[7thDimension]

OK, thanks guys, I'll check everything that was mentioned...

[seamus2154]

With that mileage a fuel filter should definitely be on you to do list.

[M I C H A E L]

yep should be changed every 60k

[7thDimension]

OK, will do.