100a fuse blows on crank

NSNO_RJB

Hesitantly Boosting
Premium Member
Location
Sydney
First Name
Ronan
Drive
1998 VR4 Galant
Hey guys, just got my engine going again. And if the car ever takes longer than 3 or 4 seconds to start it blows a 100a fuse (I have a 100a at the back for my battery relocation + the factory 120 at the front).

Found a 30-50 ohm short (it fluctuated sometimes) on Fuse #13 but I doubt that's the issue since the 30A fuse protecting that is still fine.

Apart from that I'm stumped. Stock alternator, was charging fine when the car does run. only things I have that draw more on crank would be maybe the COP kit and a 340lph pump.

Any idea would be mad. Thanks
 

mezje

Leaving Skid Marks
Moderator
Premium Member
Location
Melbourne
First Name
Maxim
Drive
1998 Galant VR4 Manual
Check your grounds and the alternator connector - do you have the rubber boot over it?
 

NSNO_RJB

Hesitantly Boosting
Premium Member
Location
Sydney
First Name
Ronan
Drive
1998 VR4 Galant
Check your grounds and the alternator connector - do you have the rubber boot over it?
So I swapped it to a circuit breaker to save myself changing Fuses while I fault find. Now works perfectly. Maybe a dodgy batch of Fuses?
 

BCX

Administrator
Moderator
Premium Member
Location
SA
First Name
Bill
Drive
2000 Galant Type-V
1997 MK Triton GLS [6G74 conversion]
2019 i30 N-Line
I believe the starter motor is 1.2kw. So roughly would be 100a at 12v in theory. Practically probably not drawing that. But cos battery is relocated, you have your ignition system drawing current as well (10-15a with fuel pump running at a guess)

You might just need to go a bit higher than 100a provided your cable can carry it.

fuse type will also play a part. My battery is still in normal spot but using a projecta bt950-p1. Comes with a dedicated cal2 fuse which I've never blown even when cranking for extended periods.
 

NSNO_RJB

Hesitantly Boosting
Premium Member
Location
Sydney
First Name
Ronan
Drive
1998 VR4 Galant
I believe the starter motor is 1.2kw. So roughly would be 100a at 12v in theory. Practically probably not drawing that. But cos battery is relocated, you have your ignition system drawing current as well (10-15a with fuel pump running at a guess)

You might just need to go a bit higher than 100a provided your cable can carry it.

fuse type will also play a part. My battery is still in normal spot but using a projecta bt950-p1. Comes with a dedicated cal2 fuse which I've never blown even when cranking for extended periods.
i figured the 100A might have been a bit on the low side, i do have a 120a sitting there spare in case. didnt really want to risk popping the OEM 120a fuse and having to source one less than 2 weeks away from tuning day haha

hopefully all keeps working
 

Rasheid Doctor

Idling at the Lights
Location
Montego Bay, Jamaica
First Name
Rasheid
Drive
99 Galant
The original main power on the starter is not fused and is generally on its own heavy gauge wire directly from the positive battery terminal. If you think you need a fuse, calculate the amperage and you can probably use a "speaker amplifier fuse" with the same amperage. Other than that you can just use a heavy gauge wire directly from the battery
 
Top Bottom