Wiring in Fuel Pump off C20 XE Loom

[Slatter]

Right ive got the starter working etc but am having probs with fuel pump.

As my car is was a 1.2 is didnt have wiring for the pump... I have got the blue/red wire on the plug of the astra loom but when ignition is on its only got 4volts there ... which isnt enough to switch the relay which ive installed.

So could i tke the normal switched live from my cars original loom and run the fuel pump off that ??????????///

Also on the Astra loom theres a thickish Red and Black wire .. Not the starter motoer one... Anyone have any ideas what it may be ????

Ohh 1 more .... there are 2 black wires on the astra plug .. which of these need power for the ecu 1 or both ???

Cheers Slatter

[Stuart]

i hope you fitted a proper fuel pump relay type of relay (if that made sense)

[Aragorn]

the XE fuel pump relay is part of the loom and has 6 or 7 wires going to it

the red/blue coming off it should be the feed TO the pump

it only goes live for a second or so after enabling teh ignition then should drop out again till u turn the key

red/black is normally a starter trigger...

i'd connect both blacks to ignition live to be safe

do u have the original FPR wiring and connector or have u patched summat together..

[novax]

Dude,

have a read of this as well, it's important you do.

http://vaux-md.net/injection/pump.htm

Hope it helps

[Ste_Nova]

just run the red/blue direct from the relay to fuse one in the fuse box... then to the pump

[Slatter]

yeah but ste there is only 4 volts coming out the blue red wire out the astra main plug Its not running the pump

[Ste_Nova]

faulty fuel pump relay or wiring then

[Slatter]

hmm well i dunno ... relay is ok cos runs my valver astra ok

would it be ok if i just wired it in ... through a relay so it worked as soon as the ignition was switched on ??? i mean its got a return hasnt it !

I take it its the ecu which control it to run when its turned over and started running ????????

[Ste_Nova]

fuel pump relay has 2 coils in it


one for ecu power

and one to switch the fuel pump when the engine is cranking

you have tested the relay so it must be a wiring fault

switched relay is bad... i almost died in a rst cause it was wired that way

[Slatter]

yep cheers ste .. im understanding a bit more now

2 coils make sense .. will have to get a haynes manual and have a play when ive sobered up after christmas !!

[novax]

Slatter - the idea for this special relay is to stop fuel pumping into the burning engine bay in a bad accident, when the engine stalls the fuel is cut off.

[Slatter]

well im gonna have a play with it as soon as i can ... then if it dont work one of my car sparky mates gonna come and see it .... recons he can make the pump prime when my door opens :lol: then take a wire off a sensor or something i dunno ill let him do it

[Ste_Nova]

recons he can make the pump prime when my door opens

20xe pumps don't prime

[novax]

Most Vaux's use the same Bosch pump (0 580 464 008) behind the rear drivers wheel and your fuel rails remain full of fuel even when the engines not running. The 2 second running is there to return it to the correct pressure for cranking.

[Ste_Nova]

The 2 second running is there to return it to the correct pressure for cranking.

20xe engines don't prime

[novax]

Ste, what do you mean by "prime"? It's a standard feature of all Bosch jetronic and motronic injection systems to run the pump for only 2 seconds if the engine doesn't crank over. If you just turn the key straight away then I'll agree with what you're saying, it just starts. There is no need to prime the system in the classic sence of the meaning as the fuel lines stay pressurised to prevent fuel locks in them on hot days etc.

[Slatter]

All sorted foud a wire which made it work :D

[Ste_Nova]

Ste, what do you mean by "prime"? It's a standard feature of all Bosch jetronic and motronic injection systems to run the pump for only 2 seconds if the engine doesn't crank over.

the pump doesn't run till the ecu recives a crank signal

[novax]

yes, thanks Ste. I did some research after reading your post. Which means i got off my ass and read the Motronic manual I have from Bosch :D What it says is this

<quote>
To prevent fuel pump operation after an accident, the pump is connected through a safty circuit. The micro computer controls the pump through a relay that switches the pump on and off. It is switched on only when terminal 50 of the starting relay is connected to battery positive or the instantaneous engine speed is above a set minimum. If the engine stops with the ignition turned on, the microcomputer-controlled pump relay interupts current to the fuel pump
</quote>

So I think the up-shot of this is

Jetronic - 2 second prime (Novas, earlyer 8v engines)
Motronic - No prime, straight off the ignition signal

Learn something new every day :D