David_17
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| posted on 10/4/11 at 03:39 PM |
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Cooling fan and fuel pump
Hi again guys.
Had a play with my wiring today as the cooling fan wasn't working. Turns out I'd taken an earth instead of a live to the relay.
Sorted that and now the fan works fine (controlled by switch on the dash or temperature controlled by the megsquirt.)
The problem i've got now is, if my overun switch on the dash is turned off, the fuel pump doesn't kick in and the engine won't
start.
If i switch the fan on, the engine will start fine and i can then switch the fan off and it will stay running.
Very confused, any ideas?
Both the dash switch and megasquirt fan wire are joined together, then go to the negative side of the relay.
Hope someone can shed some light.
Cheers
Dave.
Here's a pic of how the car's coming along.
[Edited on 10/4/11 by David_17]
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daviep
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| posted on 10/4/11 at 03:59 PM |
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Do you have a wiring diagram or a drawing?
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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David_17
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| posted on 10/4/11 at 04:15 PM |
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Hi.
I've used this diagram for my car. Except i've got megasquirt not jolt and the fan relay is switched via the earth not the live.
http://www.haynes.co.uk/forums/attachment.php?attachmentid=929&d=1282257619
[Edited on 10/4/11 by David_17]
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adithorp
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| posted on 10/4/11 at 05:29 PM |
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Doesn't appear we can view that link without beening a member.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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David_17
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| posted on 10/4/11 at 07:11 PM |
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oops.. never thought about that.
Here's how it's wired...
The purple wire (SPR3) goes to the negative side of the fan relay. (although mine is orange and black striped)
[Edited on 10/4/11 by David_17]
[Edited on 10/4/11 by David_17]
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adithorp
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| posted on 10/4/11 at 07:39 PM |
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Well that all looks right. Don't know MS but thats switched earth for the pump by the MS? Have you missed an earth somewhere on the MS? After
that I'd be checking all the relay conections are right.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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daviep
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| posted on 10/4/11 at 09:16 PM |
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Obviously something is not wired as per the drawing, your going to need to do bit of diagnosis work.
With you fan switch in the off position:-
Is everything else working correctly - if not what is and isn't operating
Is the "Switched Master Relay 70A" on page 1 coming in when the ignition is turned on?
Is the "Ignition Relay" on page 4 coming in?
[Edited on 10/4/11 by daviep]
“A truly great library contains something in it to offend everyone.”
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David_17
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| posted on 11/4/11 at 08:26 PM |
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Cheers for your help so far guys.
Right had a bit more of a play this evening.
It turns out, it's not just connecting the fan up makes the fuel pump prime, switching the lights on/off or flashing the main beam makes it work
too.
So it sounds to me like an earth problem, but i've checked all the earth connections and they seem fine.
Any ideas??
All the relays seem to be working as they should be, and the fuel pump is fine once the engine is running.
I also found that unplugging the fan relay sorts the problem too.
Hope someone can give me a clue.
Cheers
Dave
[Edited on 11/4/11 by David_17]
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