When I check the voltage to my fuel pump wire - not connected to the pump its around 12.40 volts - fine!

When I check the voltage to my fuel pump when its connected and working its 10.36 volts - not so good!

Wheres the almost 2 volts going and does this mean my pump is focked! Id measure the amps but I cant work me meter

Cheers in advance

 

bttt

 

Somethings definately not right.

Check all the cables, especially the earth points.

Could need just a clean up of the connections or maybe a complete rewire. It may even be a tired pump drawing more current than the cable can supply, so the volts drop.

Ben

 

Knackered wiring or a bad earth, just run new wiring for it using the old wiring to activate a relay to switch it.

PJay

 

Thats what I was thinking mate because the wire is of good quaility and guage, its also quite new - like a year old!

So is that perfectly possible or likely then?

Dave.

 

If the pump was drawing more current than the cable could supply the cable would melt

 

The volts must be dropping for some reason!

 

Its either high current draw, faulty pump or a wiring problem.

The easiest to test is by we doing all the earth points around the pump/pump craddle/chassis.

Ben

 

The car wont run properly either so maybe it is a faulty pump?

Cheers for help.

 

It is possible the pump is faulty, have you checked the fuel pressure as suggested the other day?

 

Yeah and it goes to 5 bar when first primed!

Then when the car is running it sits around 3!

Sound any good?

 

Was this measured at the rail? I'm not sure what fuel pressur the frst runs TBH but i'm sure someone will

 

Those pressures sound OK to me, not sure what specifically the FRST fuel pressure is meant to be but my mate's mk2 rally car which runs 2x 45 DCOE's goes to about 4.5 bar when primed and then 2.75 when running. When you measured this pressure was the car running OK? You want to know what the prerssure is when the car isn't running OK to relate the running problem to the fuel pump. HTH

 

when the pump is running, the connections accrom the pump, will drop voltage slightly because it is running, this is normal.

 

Inside the tank on the frst there is a small black box, which is some sort of choke to stop electrical noise. This actually melted in my old car Check this aswell and try and bypass it see if this cures any probs

 

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