omega0684
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 posted on 20/3/09 at 02:20 PM |
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My Megasquirt woes are back
i've just gone to start me car to head over to see Tim so that we can check over his car before his SVA and mine won't start!
in fact there is not pump priming at all, check the fuses to find that the 3 amp fuse on the 12v supply to the fuel pump had blown and the 15 amp fuse
to the injectors as well, after replacing them the car still won't start and the 3 amp fuse has blown again, why could this be, the car was
working fine yesterday.
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iiyama
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| posted on 20/3/09 at 02:25 PM |
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3A on the fuel pump?? Seems low to me bud, most injection pumps are pulling 8-11A
If its broke, fix it. If it aint broke, take it apart and find out how it works!
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omega0684
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| posted on 20/3/09 at 02:32 PM |
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no i have 10 amp fuse of fuel pump, 3 amp going to MS
wiring diagram here
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t16turbotone
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| posted on 20/3/09 at 02:36 PM |
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you need to start disconnecting things one at a time mate, untill you find the culprit
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omega0684
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| posted on 20/3/09 at 02:38 PM |
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it looks like there is no signal from the MS to the fuel pump relay, i have tested both relays and that seems to be the only thing i can find, have
been disconnecting wires and testing voltages for an hour now and im now stuck that why ive turned to the furm for help
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theconrodkid
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| posted on 20/3/09 at 02:41 PM |
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on mine the pump wouldnt turn off,turned out to be the tranny that switches the pump relay,could be yours tranny has failed the other way?
who cares who wins
pass the pork pies
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02GF74
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| posted on 20/3/09 at 02:57 PM |
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you syaing the fuse to megasquirt blew?
and after you replaced it with same rated fuse, it is ok?
re: signal to relays.
I am not familiar with the MS circuit but most liklely there is a micro with I/O lines; there will be resistor from these to base of transisitor that
is connected one end of the relay coil, other end of coil goig to 12 V.
At whcih point o nthe circuit are you seeing no signal?
If you are able to turn on/off the lines to the relays, then you should be able to measure the voltage at the resitor - this should change between 0
and 5 V, otherwise the micro is not healthy.
If the voltage does chahnge but coil is not being switched, then likely the transistor is dead. You have snubber diode fitted? (I seem to recall
these being part of the board ).
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twybrow
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| posted on 20/3/09 at 02:58 PM |
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Just spoken to Alex - it turned out to be a snapped earthing point. He now has the fuel pump priming, although his car is in bits....!
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Krismc
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| posted on 20/3/09 at 03:20 PM |
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i put a 15Amp everywhere, i find they last longer!
Built, Ivaed, Drove and now Sold - 2011 MNR VORTX RT+ 2000cc Zetec on R1 Throttle boddies.
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omega0684
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| posted on 20/3/09 at 03:25 PM |
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as tim said , i found that a bad earth on the fuel pump had snaped, (God knows how) but my car now looks like a half built one! no dash, no tunnel, no
seats, wiring hanging out everywhere! huff got to put it all back together now!
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02GF74
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| posted on 20/3/09 at 03:26 PM |
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quote:
Originally posted by Krismc
i put a 15Amp everywhere, i find they last longer!
that is bad advice. let me tell you why.
when I was much much younger, a built a PWM power controller for 00 guage train. It worked great.
One day I took the wheels off the locomotive and refitted them to find the 1 A fuse blew. So I replaced it with another 1 A - same. To save fuses, I
use strands of wire, still the same.
So I put in quite a few strands = quite a few amps. The fuse did not blow this time but smoke stated to come out of the power controlleer!!!  The
power amp blew.
Turned out that I fitted one set of wheels wrong way round so was shorting out hte track!!
From that day on, I keep to correct rated fuses.
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mcerd1
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| posted on 20/3/09 at 03:39 PM |
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someone told me they once saw a forklift mechanic finding damaged/broken wires by swapping the fuses for 6" nails and waiting to see where the
smoke came from
[Edited on 20/3/09 by mcerd1]
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