ds13

I just swapped a ls1 into my s14 240sx, I used a standalone harness. It cranks for a second then blows the 100a fuse. Any ideas on what it could be?

k_cash1432

iTrader: (9)

What fuse are you using that you need 100a? If it is the starter maybe you have a brush inside the motor that is shorting to ground causing the fuse to pop...

k_cash1432

iTrader: (9)

Or maybe 100a isnt enough for your starter.

Old Geezer

iTrader: (3)

^^^^^^^^^^^

ds13

Yea the 100a is for the starter, my friend has the same setup and uses a 100a fuse.

ds13

What do you mean a brush inside the motor?

TomM

iTrader: (56)

You need at least a 250 amp fuse for the starter......

T,

ds13

Alright ill try that thank you very much

Pop N Wood

iTrader: (1)

There is no real reason to fuse your starter

Emdmechanic

iTrader: (2)

Thats my thought also.

FastKat

iTrader: (10)

Agreed - no fuse. If anything, get a length of fusible link and use that.

i r teh noobz

iTrader: (4)

DC electric motors use brushes to conduct current to the rotor. They are the part that usually wears out.

I run a 250a fuse for my whole car, starter and all.

ds13

i went to autozone and asked for a 250a the guy said hes never heard of one, guessing the guy didnt know what he was talking about

cartel

they make a 200 amp fuse

an industrial supply for large trucks might have 250s.. i tried a 100 same as you it blew a 200 worked

ds13

its just weird that my friend uses a 100a and his is fine, is there supposed to be a ground to the starter?

LS1MCSS

iTrader: (18)

Yep, dump that fuse. It's not needed.

i r teh noobz

iTrader: (4)

I use the stye intended for amps. Its quite large and bolts into a little holder. They're all over ebay for under 10 bucks with the holder.

A fuse isn't really needed, but my battery is in the trunk with several feet of cable running underneath the car. I fused it in case I bottom out and crush the cable or something.

You can never have too many grounds. I torched my first starter due to poor grounding. A strap from the block to the fender cured my issue, but a direct ground to the starter isn't a bad idea.

Pop N Wood

iTrader: (1)

Believe it or not this car audio site has a most excellent selection of fuses.

ANL fuses go to 300 amps I think.

Yeah, I guess if I had a trunk mounted battery i would be tempted to run some sort of fuse. I never ground anything to the frame so I agree with running a negative cable from the battery to the block.

Lots of things can affect starter current draw. Bigger motor, higher compression and starter type all affect it. Get a geared ministarter and current draw drops. Car companies (GM included) are starting to switch to permanent magnet starters cause they are smaller and draw less juice than the old brush type starters. But believe it or not a weak battery or dirty battery post could easily make a 100 amp difference in starter draw. if you can't get the full 12V to the starter current draw goes up massively. Running the ground current through rusty body panels will have the same effect as dirty battery posts.

the_merv

iTrader: (88)

The block is the ground..make sure you have the neg side of the battery connected to the block in some way, and the chassis also grounded to the neg side. If you don't have the block grounded that is most likely your problem.

I run factory grounds from the neg side to the block and the fender, and I add a 4ga jumper from the one on the block to the Frame Rail, and a second one on the other side from block to frame rail. You can never have too many grounds.
I don't have any large fused 12v to any of my starters and I have no issues. All of them are 12v straight from the battery.

bczee

iTrader: (12)

Question, just to clean the air.. is the fuse inline with the battery to starter or the IGN to starter Solenoid ?...

I would recommend larger battery cables and good grounds as other above have stated (Pop, the_Merv).. The total resistance of the starter, connectors, ground and wires are running very high on your setup if you keep blowing the fuse. You might check the starter, it might be pulling more resistance and amp than normal. Maybe a new or different starter might also be the answer.

Hope you get is resolved soon.

BC