fuel pump wiring and ecu/relay/fuses re-location

[Hollowpockets]

Mentioned doing this before but have now arranged for an auto electrician to come to the house and do this tomorrow. (I don't want to cock it up) Search function is down so need some help from you clever guys out there.

Firstly I think I'm needing extra wiring for my second fuel pump, already have the upgraded harness but want to know if the wiring can simply be split between the two and can they both work off one relay? OR give each pump its own set?

also does anyone have pictures or a rough guide as to what is required wiring wise to re-locate the ecu/fuses/relays from the engine bay side of the bulkhead to behind the drivers seat?

Ill be leaving the battery as is for now and re-locating that at a later date, I don't want to mess with too many things at once.

Cheers

Graham

[TuxMan]

Hi Graham , I used this setup




2 x supply,s straight from battery along with 2 X 30 amp relays fused at 20 amp .

[Acrowe]

Hollowpockets said:

Mentioned doing this before but have now arranged for an auto electrician to come to the house and do this tomorrow. (I don't want to cock it up) Search function is down so need some help from you clever guys out there.

Firstly I think I'm needing extra wiring for my second fuel pump, already have the upgraded harness but want to know if the wiring can simply be split between the two and can they both work off one relay? OR give each pump its own set?

also does anyone have pictures or a rough guide as to what is required wiring wise to re-locate the ecu/fuses/relays from the engine bay side of the bulkhead to behind the drivers seat?

Ill be leaving the battery as is for now and re-locating that at a later date, I don't want to mess with too many things at once.

Cheers

Graham

Depends on the size of the cable that was run from your battery or starter motor. I think the 044 pumps can draw upto 15.5 amps, so if you have two of them you would need a cable that can handle 31 amps. I have run a 6mm2 cable to allow for two pumps to be run from the same cable. You could probably get away with 4mm2 but I would not go for any smaller.

[funkybmx1]

TuxMan said:

Hi Graham , I used this setup




2 x supply,s straight from battery along with 2 X 30 amp relays fused at 20 amp .

I'm guessing you done as I said and put another fuse by your battery so if that comes off you ain't got live wires floating around by your tank I thought

[TuxMan]

Yep , all done thanks . Tux

[anotherdom]

Have a look on the US site - peterguk did a very neat job of relocating his and posted up photos here:

http://nobleforums.com/showthread.php?t=7342

Can't remember the formatting to link on iPhone!

Dom.

[andygtt]

a relay for each pump is the best option, use the original relay to switch these 2 relays on.

[Hollowpockets]

Thanks everyone, perfect info and gives us a head start.

I hope to have her running by Saturday.

Graham

[bzguy]

I would consider 2 relays as well, 1 for every pump, and 1 fuse for every pump as well.

Pumps take a lot of current to start, since coils are inside.

Correct me if I'm wring

[Blu3R]

My only concern with 2 relays is around failures. With only 1 relay if it fails then you lose fuel supply and the car abruptly stops. If you run a pair and 1 fails (which is now twice as likely) then you only know once you've melted a piston at 8krpm.
I'd build in some kind of dash warning whatever route you choose.

[brb]

Acrowe said:

Depends on the size of the cable that was run from your battery or starter motor. I think the 044 pumps can draw upto 15.5 amps, so if you have two of them you would need a cable that can handle 31 amps. I have run a 6mm2 cable to allow for two pumps to be run from the same cable. You could probably get away with 4mm2 but I would not go for any smaller.

how many mm2 for x A



total length is positive length + negative lenghth

[TuxMan]

In theory the engine will be fine on 1 pump but I have fitted a stack fuel pressure gauge on the dash that glows bright red if the fuel pressure drops below 3 bar !!!! Should keep things safe ..... I hope :-)) Tux

[D_G]

I took my main supply of the back of the starter (5 speeder) with a waterproof fuseholder and 20amp fuse. Makes the wiring much shorter and tidier rather than going to the battery.

[andygtt]

I decided the best way was to make the ecu read fuel pressure and set mapping strategies to ensure it doesn't blow the engine up

[Mike Tuckwood]

Monitoring simple Fuel pressure could potentially give you a false sense of security, if you have a fuel pressure issue and you're on boost, the only way to realistically avert catastrophe is to be monitoring "differential pressure" Boost and fuel referenced against each other.

The only gauges i've come across capable of doing this are Defi gauges, I have these in both of my 'tuned' cars.


Mike.

[andygtt]

exactly... your pumps need to be supplying well over 4 bar on full chat... unless you mapp for static constant fuel pressure regardless of boost (I know this has been done) then the guage wont help.
must admit didnt know you could get rising rate guages... pretty sure my stack doesnt display rising rate alert!

[Blu3R]

So some simple current sensing for each pump feed would be better, fed to a dash LED.

[Mike Tuckwood]

Blu3R said:

So some simple current sensing for each pump feed would be better, fed to a dash LED.

I can't quite see how that would work? Fuel pumps can be drawing normal amperage, but efficiency can drop off?

Mike.

[951]

Would it not make sense to just fit a wideband o2 sensor and put an AFR guage in?

That's what I did on my other car.

Regards

Graham

[funkybmx1]

951 said:

Would it not make sense to just fit a wideband o2 sensor and put an AFR guage in?

That's what I did on my other car.

Regards

Graham

That's what Steve has done. Actually don't think there is much he ain't. And we're all copying or I do anyway . Sorry steve