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Location:
Ipswich
Registered:
May 2002
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Fuel pump and wiring question
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Sun, 04 January 2004 13:57
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I'm currently wiring up my Corolla KE35 with a 4AGE in it, have a question regarding fuel pumps.
On the 4AGE, the fuel pump runs directly off the wiring harness (via the main relay I think - darn it where is the correct wiring diagram when I need it...). However because it's in a previously carby car, I have 2 fuel pumps - 1 facet style low pressure pump and 1 VL high pressure pump. Can I still run both of these off the wiring harness? I've been told fuel pumps don't take a lot of power, but am wondering if I should run these off a relay...
Also, wiring up the chassis and something strange is happening. I've wired in the 12V+ into the main chassis harness, don't have my starter, head/tail light, flasher relays yet so obviously those things don't work yet. Most other things seem to work (stop lights, radio circuit, interior light, clock etc). However, whenever I try to run any motors (heater fan, windscreen wipers, windscreen washer) the motor doesn't run, but instead the dash indicators (not the actual indicators - just the dash ones) turn on. However, if I unplug it completely from the loom and apply 12V to it, it runs. I've looked and looked at the wiring diagram, can't see any reason for this to happen. Even when it's wired up if I turn it on (and it doesn't work, dash indicator turns on instead) and put a volt meter across it, it reads 12V. But the motor isn't running.
Any ideas? Is this because I don't have the relays in yet?
Thanks
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Location:
Melbourne
Registered:
October 2003
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Re: Fuel pump and wiring question
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Sun, 04 January 2004 14:51
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would now be a bad time to say
"its just gotta be a bad earth" ? (I think so)
Anyway, I've been looking at the two pumps current draw myself and was directed to:
http://www.bcae1.com/
to help me out. I reckon it will answer my questions when I come around to asking them again.
Hope it helps you too, thank 'septembersquallindustries' if your answers lie within.
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Location:
Ipswich
Registered:
May 2002
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Re: Fuel pump and wiring question
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Sun, 04 January 2004 16:22
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Hmm, you're probably right about the bad earth, will check my loom again to see if there are any earthing points I'm meant to earth. I wonder why all the lights etc work but not the motors... Bizzare 
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: Fuel pump and wiring question
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Mon, 05 January 2004 03:07
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are we talking about your wiring to the 12 pin plug on the ecu?
if you are i can help identify what you do and dont need to connect. By the sounds of it you might be wiring up things to ELS2(or ELS1) when you dont need to.
Let me know, i worked it all out when i did the 4age into the AE71.
PS- big or smallport?
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Location:
Ipswich
Registered:
May 2002
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Location:
Brisbane
Registered:
February 2003
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Re: Fuel pump and wiring question
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Mon, 05 January 2004 03:23
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tends to be common to control fuel pumps via a relay - saves having the ECU switch (or send-to-earth) a high current load.
also, EFI pump relays often have a current limiter built in so the pump doesn't suck away precious power when you're idling or trying to start the engine. This tends to require two relays, one to switch power-to-pump on/off, the other to send current direct, or thru a big resister (current limiter).
also 2, by using a relay to drive the pumps, there's no fuse between the ECU and the relay, only betwen 12+ and the pump.
charles.
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Location:
Ipswich
Registered:
May 2002
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Re: Fuel pump and wiring question
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Mon, 05 January 2004 03:55
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karl: hmm, I have a feeling my pinouts are a little different (small port) but I might be wrong. I haven't actually wired it up yet, still trying to finish the chassis wiring. I've only gotten as far as looking at the diagram and labeling all my ECU pinouts.
I'll check the resistance on the pumps and work out how many amps I need to run both pumps and put a relay in
thechuckster: are you saying there's a special sort of relay for efi fuel pumps? So I can't just use a normal like... horn relay?
Thanks!
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Location:
Brisbane
Registered:
February 2003
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Re: Fuel pump and wiring question
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Mon, 05 January 2004 05:47
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| demuire wrote on Mon, 05 January 2004 13:55 |
thechuckster: are you saying there's a special sort of relay for efi fuel pumps? So I can't just use a normal like... horn relay?
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you can use normal relays to turn them on/off, but the loom on my 1G-GTE had a 'fuel pump relay' - that was controlled by the ECU and fed from the circuit opening relay for a 12V+ source.
the wiring diagram here on page 1 of this PDF <http://members.optushome.com.au/mkhala/red_celica/ 1G-GTE_info/1g_gte_ecu_wiring.pdf> shows how it's wired up for the 1G - but the principal would be the same (i hope)
depends if you want the main pump to do the 'low power use' thing - but if you think your electrical system has enough capacity regardless of engine revs then don't bother. (But base your highest-current-requirement estimate on a worst case scenario (night-time in rain, passengers, hi-beam, engine under heavy load, etc.)
charles.
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Location:
Ipswich
Registered:
May 2002
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I supported Toymods
Location:
melbourne.victoria.austra...
Registered:
June 2002
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Location:
Ipswich
Registered:
May 2002
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Re: Fuel pump and wiring question
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Mon, 05 January 2004 06:16
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grega: yes i know. but it doesn't have the fuel pump relay like in Charles's diagram.
The pins and colors on my ECU match the ones in that diagram (apart from mine missing a few things like TEMS suspension controller etc), so I would assume I have the correct one...
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