Printable Version | Subscribe | Add to Favourites
New Topic New Poll New Reply
Author: Subject: Ignition Fuse keeps popping
bikecarbfred

posted on 11/2/19 at 04:01 PM Reply With Quote
Ignition Fuse keeps popping

Took engine in and out a few times. Ignition fuse keeps popping now on "ON" position (no cranking)

Wire diagram below. As Fuse F4 keeps popping instantly, is it safe to say anything that I have marked red could be the problem?

I have removed every singly accessory fuse including lamba sensor, fuel pump etc. Fuse still pops instantly.
Severe short circuit.



View User's Profile View All Posts By User U2U Member
gremlin1234

posted on 11/2/19 at 04:27 PM Reply With Quote
it won't be the HT side of things, -distributor, sensor, or plugs, (30, 32 & 31)
it wouldn't be the brown wire earthing the amp either.

I would put a bulb across the fuse terminals, (test with a 5W 12V bulb first)

then I would disconnect the ignition amp, see if it still draws such a high current.

my guess would be a short in the fuse box itself.

View User's Profile View All Posts By User U2U Member
bikecarbfred

posted on 11/2/19 at 04:41 PM Reply With Quote
On the HT side of things

28, 29, 30, 31 & 32 are not being used as im running bike carbs with stand alone ECU megajolt.

View User's Profile View All Posts By User U2U Member
Angel Acevedo

posted on 11/2/19 at 04:43 PM Reply With Quote
Unplug Everything no fuse and check continuity to ground at all points.
Any short will show readily as continuity to ground.





Beware of what you wish.. for it may come true....

View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member
bikecarbfred

posted on 11/2/19 at 04:47 PM Reply With Quote
Angel,

so volt meter set to continuity. and one lead on ground points and other lead on where? Fuse box points?

And if i hear buzzing noise then theirs problem?


Does ignition switch obviously need to be turned on for this testing?

View User's Profile View All Posts By User U2U Member
gremlin1234

posted on 11/2/19 at 04:49 PM Reply With Quote
quote:
Originally posted by bikecarbfred
On the HT side of things

28, 29, 30, 31 & 32 are not being used as im running bike carbs with stand alone ECU megajolt.
if you are not using the above items, then the circuit doesn't do anything. have you perhaps terminated a random black wire to chassis? like you would on a lucas loom?

View User's Profile View All Posts By User U2U Member
Angel Acevedo

posted on 11/2/19 at 05:12 PM Reply With Quote
quote:
Originally posted by bikecarbfred
Angel,

so volt meter set to continuity. and one lead on ground points and other lead on where? Fuse box points?


Yes, If there´s a short in any cable run you´ll hear buzzing.


quote:
Originally posted by bikecarbfredAnd if i hear buzzing noise then theirs problem?


Does ignition switch obviously need to be turned on for this testing?


As stated by gremlin123, even if you have everything but you don´t have 28, then you don´t need that fuse/cable unless you are planning for future upgrading.
You may terminate at the switch, remove the fuse or terminate after the fusebox. Terminating after the fusebox with a short cable properly insulated at the end may allow for future changes or using as spare circuit.





Beware of what you wish.. for it may come true....

View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member
Angel Acevedo

posted on 11/2/19 at 05:15 PM Reply With Quote
quote:
Originally posted by gremlin1234
quote:
Originally posted by bikecarbfred
....have you perhaps terminated a random black wire to chassis? like you would on a lucas loom?


Being marked Sw = Schwarz (Black) this must be the culprit.

[Edited on 2/11/2019 by Angel Acevedo]





Beware of what you wish.. for it may come true....

View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member
bikecarbfred

posted on 11/2/19 at 07:38 PM Reply With Quote
if on connector 28 , if all three wires were cut and taped up together, that would 100% cause a short circuit to blow fuse number 4?
View User's Profile View All Posts By User U2U Member
wylliezx9r

posted on 11/2/19 at 07:43 PM Reply With Quote
quote:
Originally posted by bikecarbfred
if on connector 28 , if all three wires were cut and taped up together, that would 100% cause a short circuit to blow fuse number 4?


Yes it would. Tape them up individually or use terminal blocks.

[Edited on 11/2/19 by wylliezx9r]





I spent a lot of money on booze, birds and fast cars. The rest I just squandered.
George Best

View User's Profile E-Mail User View All Posts By User U2U Member
bikecarbfred

posted on 11/2/19 at 07:48 PM Reply With Quote
i didnt do any multimeter testing. just saw those three wires loosly taped with electrical tape.
i undid the tape and noticed the were all touching each other.

not sure how the car drove for last two years.
i might have squeezed the tape in last few weeks while doing engine work causing the wires to touch even more.

anyway no fuse popping now.

View User's Profile View All Posts By User U2U Member
gremlin1234

posted on 11/2/19 at 09:40 PM Reply With Quote
quote:
Originally posted by bikecarbfred
if on connector 28 , if all three wires were cut and taped up together, that would 100% cause a short circuit to blow fuse number 4?
yes 100%,
but they didn't do a good job of joining them in the first place, if only now does it blow fuses.
I don't know if you should tie connector 28-2 Gn/Ro (green/red) high or low, but from looking at the circuit, I think best to leave it 'floating'

edit: it would have worked for the last 2 years, because the circuit doesn't do anything, Why did you check the fuse and then find it blowing?

edit2: well done for finding that!

edit3: remove fuse 4 it doesn't do anything, then it should all play nicely ;-) but do terminate the other end or the sw (black) wire cleanly too


[Edited on 11/2/19 by gremlin1234]

View User's Profile View All Posts By User U2U Member
bikecarbfred

posted on 12/2/19 at 06:50 AM Reply With Quote
gremlin, i can't remove fuse 4.
i need it for megajolt and edis coil because it's the only slot that stays live when cranking i believe so the sparks plugs can fire when cranking which is crucial.

View User's Profile View All Posts By User U2U Member

New Topic New Poll New Reply


go to top






Website design and SEO by Studio Montage

All content © 2001-16 LocostBuilders. Reproduction prohibited
Opinions expressed in public posts are those of the author and do not necessarily represent
the views of other users or any member of the LocostBuilders team.
Running XMB 1.8 Partagium [© 2002 XMB Group] on Apache under CentOS Linux
Founded, built and operated by ChrisW.