Fuel Pump Voltage??

[ram5ay]

Ok, so I've read a few posts about this, and was curious to see what the voltage feed to mine was, I measured it yesterday and it was only 11.8v with the engine running. (14v at the battery)

What I'm wondering is if this is normal? has anyone ever measured a much higher voltage at the pump and not needed to run a new feed?
If I'm not planing on running much more than a bar and I allready have a higher flow rate pump is it really necessary?

Also does anyone know if there is a resistor in the fuel pump circuit that allows it a higher voltage when it needs it (on boost?), so it isnt working so hard when it's not needed. I have been told this in the past, as with skyline GTR's, and that if you bypass this resistor your pump will flow more???

Any help/comments appreciated,
Thanks

 

[MarkTurbo]

Also does anyone know if there is a resistor in the fuel pump circuit that allows it a higher voltage when it needs it (on boost?), so it isnt working so hard when it's not needed

I might be wrong :lol: But i'm pretty sure the pump just runs at the same voltage all the time, and the job you've described above is what the fuel pressure regulator is there for

 

[ram5ay]

Yeh, you're probably right. I was just hoping I could be lazy and get round running wires and fitting relays an stuff :roll:
I know the fpr increases fuel pressure in relation to manifold pressure, but from what I was told I gathered that the pump feed would switch to a higher voltage to keep up the flow rate demand, to ensure pressure at the fuel rail.
It might make more sense to say that the pump voltage drops when it doesnt need to be workin so hard.
It was an Aussie mate who told me this, who's worked on alot of sr20's, but more in sylvia's/sx's etc. knows his stuff tho.

 

[krikra]

mine was only 11,1V :shock:
So I ran a new positive wire from the fuel pump relay.. This gave me 12V..

I then earthed the fuel pump and the voltage went up to 12,5V..
Still not impressive!?

 

[mattygti-r]

im on standard fuel pump seems fine, Fuel Pressure according to the Defi is 3bar rising to 4bar when on full boost

 

[geetee]

I had 12V but the pump wouldn't spin up.

Turned out to be massive resistance on the earth wire (some 1000's of ohms!). Re- earthed it to the chassis by the back light. Been fine since.

Just my tuppence worth

Cheers
GeeTee 8)

 

[ram5ay]

Cheers for the replies so far.

Recon I'll maybe run a new earth, and check the voltage at my fuel pump relay. I'll see if I can get some hapless "volenteer" to sit in the boot with a voltmeter, and test the voltage under acceleration/boost to see if there is any difference.