80amp inline fuse blows after about 5 seconds crankingURGENT

[Euphoricglass]

So the car..... is a usdm 95 240sx with an s14 sr20det swap that i did about 3 years years ago and never had this problem until now. The car sat for almost two years although i dont think that would have anything to do with it. Oh yeah and the battery has been relocated to the trunk with an 80 amp fuse in the line.

The problem.... after about five seconds of cranking the inline fuse blows.

What ive done..... ive pulled the main line out inspected it found one little puncture taped it up pulled the lower engine harness off and cut it completly apart to do a thurough examination of it... nothing touching. and ive takin the starter out and done a bench test and it works great every thing is back in and still popping the 80amps like popcorn. Its all looks like its pointing at the starter to me but im so frustrated im starting to lose my head ..... please help me, ive gotta have the car out of where it is buy tomarrow Thanks...Corey

[Booztd 3]

It is likely your starter motor has increased in resistance which is going to cause an increase in amperage as well. Bench testing is not necessarily a valid test in this scenario as you're not putting any load on the starter motor.

[Euphoricglass]

thanks thats what i figured, i know there is a way to test the amprage draw but i am not familiar with it. any advice would be much appreciated.....also should i try taking the fuse out of the line and running it straight? so that the excessive amprage draw doesnt pop the fuse.

[Booztd 3]

thanks thats what i figured, i know there is a way to test the amprage draw but i am not familiar with it. any advice would be much appreciated.....also should i try taking the fuse out of the line and running it straight? so that the excessive amprage draw doesnt pop the fuse.

Amperage draw is detailed in the FSM. I'm not sure what starter you have but a few are listed (mitsubishi type is one for example) and neither of them exceed 85 amperage draw under any condition. I'm not sure I'd recommend hooking it up straight, remember the power for the EFI harness, relays, chassis harness etc is supplied from the same battery terminal your starter circuit is on.....not sure I'd want to risk damaging anything else

[Booztd 3]

EL-22 for the starter amperage specs....I know you said you've done an SR so I'm not sure if the starter's match up however.

A few things I was curious about:

When did this start happening? Out of nowhere? After the battery relocation? Etc

Why are you cranking for 5+ seconds? If everything is working properly, the engine should fire after a few revolutions..

[Euphoricglass]

i took the swap out to do a head gasket, and put it back in it sat for like 2 years and here we are . It might not be starting quickly cause the starter is turning ovr kind of slowly and because i just pumped old varnished gas out of the tank and there coulld possily be a little puddle in there with the fresh gas I put in there. It does, however attempt to start.... itll fire a couple of time in the couple of seconds im cranking it. and i did the battery relocation when i did the swap. Thank you for all of your insight.

[Kevin.A]

It is likely your starter motor has increased in resistance which is going to cause an increase in amperage as well. Bench testing is not necessarily a valid test in this scenario as you're not putting any load on the starter motor.

i would like to point out I = V/R So increasing your resistance without increasing your volrage would lower your draw. What i would do to test it is, with the car off, jump the little wire (switch) on the starter to +12V, and see if it blows the fuse, if it does, your starter is shorting someware. Check for frayed wires. if you can't find any it's the starter itself. Drawing 80A for 5 seconds will make it get HOT, so you should be able to tell. Also doing this in the dark will allow you to see if anything is sparking. If something is sparking, that's what is bad.
If you don't blow the fuse, it's something else. but at least you have a starting point.