Bosch 040 Fuel Pump Questions

[adamp_r32]

Ok so i have a few questions regarding the bosch 040 fuel pump in my r32 gts-t...

Firstly i have a hard to start problem, the car will start fine of a morning after its been left over night but if i leave it for half an hour or so after driving it will crank for about 5 seconds before it fires( regardless of how many time i turn the key to ignition and prime the pump, and also regardless of whether i give it any throttle) so i dont know whether this could be linked to the fuel pump or not, but since i have tested for injector pulse, put new plugs in it, injectors overhauled and cleaned, new fuel filter and coolant temp sensor... i figure its my next place to look.

Also after starting the car i get a funny sound from the fuel pump like a grindy sort of sound, fairly loud (noticeable over the rather loud operating noise of the pump) and if i rev the car and hold revs on it, the noise dissappears. But as soon as i let it just idle again the noise will come back.

I remember reading that their is an electrical trick to do when installing the 040 to do with the voltage the pump receives? could any1 shed some light on this?

I also did a fault code check on the ecu and got code 55(all ok)

Any ideas?

Edited May 11, 2008 by adamp_r32

[nuclear_skyline]

Alls OK!? Thats probably the truth of it... Most cars crank over a little bit before they turn on... It seems as though thats normal to me...

Depending on how the pump was installed, it might be touching the side of your tank and viabrating > hence the noise... Probably does not go away, but the exhaust viabration and noise masks it...

Any of that seem possible?

[Habler]

When you go to turn your car on instead of cranking it for 5 seconds let it prime for 5 seconds (with the 040 you should hear it finish priming after about 5 seconds) then crank. If this works fine than nothing is wrong. The fuel pump just needs time to prime the fuel up. A lot of aftermarket pumps will work like this.

Correct me if I am wrong but stock pumps (and some aftermarket ones) have anti-drain back vavles meaning the fuel does not need to be primed up and will crank straight away.

As for noise, as said by nuclear, 90% of the time it's installed badly.

[adamp_r32]

Ok the noise makes sense(the vibrating) but the start-up issue must be to do with something else then, it is not normal. I primed the pump 5 times this afternoon waiting about 10 seconds between each time and it still cranked for about 8 seconds before it started. For a reasonably stock car with the standard ECU it shouldnt be doing this... aaargh!