Hey what's up RX-7 forum. I hope you guys can help me. I have a main fuse problem. (Human error I hope)

I bought a 94' FD from Japan. Had it towed for me from the docks to my place. I haven't had i running yet.

The battery was dead. So I boosted it. Which is what i think caused the main fuse to blow. When I first got the car the dash lit up, though the battery was too low to start it. After boosting the car, the dash didn't light up.

I checked and main fuse was blown so I bought a new 120a main fuse.

Here's what I want to know: Did i go wrong somewhere installing it?

I disconnected the battery.
Once i figured out it was bolted in I put in the new fuse.
Connected the positive terminal.
Went to connect the negative terminal, got spark, but had to move it a little to fit correctly which produced another spark or two or a few, it was quick.
Then the fuse blew.
I didn't get the negative even close to fully connected before it blew.

Did I go about it in the right order?
Or was it just my inaccuracy and hesitation placing the negative terminal back on that caused it to blow?

I have another two fuse's on order but I don't want to blow another.

I'd appreciate any help, thanks guys.

 

Could the positive battery cable/terminal shifted, and be shorting the fuse when inserted?

Did you check continuity around the battery and fuse area to make sure everything is kosher?

 

Positive was fully connected. I don't have a continuity tester.

 

check the polarity.It really sounds like you are hooking up the battery backwards.

 

it wasn't backwards.

Edit:
The only thing i did with the battery was move it down in it's case so i could get to one of the screws for the fuse. you couldn't hook up the battery backwards if you tried since the positive connection is connected and fixed to the first fuse box, it can't move.

 

If the main fuse is blowing something is shorting out on that primary circuit. Could be the wiring to the starter or the alternator.

Simply hooking the battery up won't blow the main fuse. A small spark is normal when hooking up the negative terminal.

Dale

 

So the car is defiantly shorting somewhere. Most likely between the starter and battery. I guess i need to start checking all the wires.

Any tips on where to begin? Any problem areas?

Edit: Thanks Dale, that's what it is. I'll start looking.

 

there is a ground wire pretty close to the starter, possibly someone could have switched the two wires so the starter lead is grounded?

I would just pull the starter lead and the alternator lead and see if the problem still exists. You can use a continuity tester between the battery terminal and a ground source rather than keep blowing fuses.

 

Time to get a multimeter and learn how to use it. It's a pretty straightforward tool, and not too expensive. A digital one with a continuity "beep" function will be handy. You'll use it more than once with these cars!

 

So my FD has a short. The battery is holding 11.47V and the short is around 10.4v

Can anyone tell where the short could be coming from knowing it's 10+volts?

 

Please clarify. Do you measure 10.4 volts across the battery terminals, and under what conditions? Also, under what conditions do you see 11.47 volts? FYI, a fully-charged battery should be around 12.6 volts when engine is off, and about 13.5 - 14.3 volts with engine idling and all electrical accessories off. Will the battery take a charge?

What is the dark current, i.e. the current flowing when everything is turned off? Should be no more than 20 milliamps or so. If more (like you would see with door open), there is a low-resistance leakage path somewhere. You would usually look for that by disconnecting one load at a time.

 

Thanks for the response.

There's a short so the battery isn't fully charged. It was 11.9 last night. Currently it measures 11.47 across the terminals.

The main fuse blew due to this short so nothing is on. I see 10.4 volts on any or most metal surfaces in the engine bay.

 

Do you have the wiring diagram and know how to read it?

 

Man i hate fd electric problems

 

Found it! Taped it up, car runs great. Thanks for all the help guys!

 

Great!
Where was it?
Could really help future people with the issue if you take the time to post specifically where it was, and what you believe was the reason for the malfunction.

 

This is my first FD so i'm not familiar with what all the wiring is for. It was between the chassis and engine, on the side with the starter above/near the transmission housing. One of those lines were cracked and touching the chassis. I didn't have to go underneath to get to it, it's visible/reachable from overhead.

Maybe i'll take a picture when i can.

 

That's kind of odd...the 94 wiring diagram shows that line is not fused and I know from experience it's not on my 93. At least you got it fixed. A little friendly advice...electrical tape gives that cheesy "shadetree mechaninc" appearance. Battery cable is cheap, get a new one and replace it.

 

Oh, it might not have been that spot then. I taped up a few other places. That one had the biggest crack and was touching the chassis so i figured it was that spot.

 

Word of warning... Vinyl electrical tape adhesive will liquefy with heat and come loose, resulting in unwrapping the tape over time.