I recently drove my car to the mechanics shop when I did manage to get it started. Luckily I didn't need to get it towed. I have had slight starting problems which I hear are common in RX7s. like when I drive somewhere I shut the car off too quickly when I should let it idle for 30 seconds. When it is time to leave my destination, I go to start it and it cranks but sounds as if it has no fuel. Then wait 10-15 minutes and the car starts up like "wtf u trippin' about?"

But, this recent one has me baffled. I am thinking it is an exposed wire on my starter or something. I am hoping my mechanic finds the solution. Anyway, I get in the car, everything is chill up until the point where I try to crank the car to start it. BAM everything short circuits. No dim lights to indicate a low battery, No beep to tell me my seatbelts aren't attached (usually even when I do buckle my seatbelt I get that stupid warning anyway).

I think I had this problem just once before and I simply reattached the negative terminal and she started right up. It wasn't this serious of a problem until now. I reattached my negative terminal after the sudden loss of power and still nothing. I attempted to jumpstart from a v8 truck (my RX7 FC for some reason cannot be simply jumpstarted from a 4 banger or other small engine). I had lights and beep in car but every time I cranked the trucks lights dimmed even when he was revving past 4000rpm!

I took the battery I had just bought at Interstate 3 months back to get it tested. They checked and did a full check and said it was fine. I then put the battery back in my car and had a good feeling it would start and sure as sh*t it started. I was miffed as heck it didn't start when I needed it to but accepted it and drove home.

I waited a day and went out to start. Did the same damn thing. Worked great right up until cranking point. I tried reconnecting the negative wire with no success. Then I figured "I took the whole battery out, reconnect the positive wire too." It started right up like nothing was wrong.

The day I took it to the mechanic. I had just left the positive and negative terminals off for days thinking I should wait 'till closer to the end of the month to bring it to the mechanic (so I have the money to pay the mechanic). So I reattached the battery like I had done last time it worked great up until cranking position on the ignition and this time it didn't start or beep afterwards but the interior lights were on but dim. I tried disconnecting and reattaching both positive and negative terminals on the battery like 3 times before I got fed up and said "Roxanne you need to run now" and I left the key in the ignition position (the spot right before cranking), connected the positive first then the negative (which sparked), I heard beeps, I jumped in the car, and slammed my foot on the clutch and it started up like nothing was wrong.

Anyway, that's my story B.A. Motorsport usually takes a while to come up with an answer (he does a very good job at a very reasonable price) but this one really has me hoping it isn't the wiring harness or something really major.

 

Sounds like loose or corroded connections at your battery terminals. Clean them really good, and replace if necessary. If your taking, and or moving the terminals around and the car "suddenly" has juice again, then its a connection at the battery.

 

Sounds like a voltage drop to the starter. I had it occurring randomly until I wired in a relay to give the starter full voltage. Do a search for "voltage drop to starter" and check it out as a possibility.

 

No, no no. All wrong
I had those exact symptons and it turns it it was the fuse block. The main wire from the alt. is bolted to the fuse block, which also feeds all of it. Im pretty sure that connection is corroded badly, or it will be loose, which is what had happened to me

 

sounds like corrosion issues, check for corrosion on your battery terminals, make sure you clean them thoroughly, and use a no-oxidation grease on them, and that they are tight

inspect wires going into fuse block and under fuses, for corrosion,

theres a semi thick wire with a stripe with a black connector about 6-8"" off the positive terminal, its maybe 1/4" thick? check that connection, as well.

then inspect your wires running to your starter

 

This sounds like the same symptoms my S4 FC displayed as a result of its alternator cable terminal crimp failing. Cable shorting out on the UIM, everything lit up in the warning light cluster but it kept going with only decreased power. Fortunately, I was only a few blocks from home at the time. Popped the hood and only 3-4 strands were still attached to the lug terminal on the alternator's output stud.

Power goes through the path of least resistance. In this case, being burnt off to ground AKA shorting out. The solution is a pretty simple procedure, just not very fun thanks to ~30 years of accumulated road filth. Plus, you're removing electrical tape that has been in place since the Chernobyl Disaster

Extract both Positive and Negative cables from the Front Harness. You'll be un-taping a good portion of it, so be sure you can spend the whole day on the project. It doesn't need to be cut, just worked loose at the start. The rest can be done just by un-winding it, pulling the cables out and re-taping the harness every few inches or so to keep it tidy.

Throw the old cables away.
Separate the Fuse Box from the Alternator cable where they are STAPLED together. You will now have a short ~6" long 8awg cable going directly to the Main Fuse. Throw the old Alternator cable away.
Now purchase the following:
11ft of 4AWG cable
8 terminal lugs with 3/8" eyelet terminals
MARINE BATTERY TERMINALS

You will be making FOUR cables total as follows. Each is slightly on the long side for easy installation
Battery+ to Starter: 4FT
Battery - to Main Ground: 2FT
Main Ground to Starter: 2FT
Battery+ to Alternator: 3FT (Do this one last, you might be able to make it shorter)

Solder them per Aaron Cake's Ground guide here: Proper RX-7 Grounding Procedures

To address the Fuse Box input, crimp on a 3/8" ring terminal (common at any regular hardware store such as Menards/Lowes). Attach the new Marine Battery Terminals to your battery and connect the cables. You'll have 3 terminals on the Positive Battery Terminal: Starter, Alternator and Fuse Box.

At the Main Ground Point, I highly recommend threading the new M6x1.0 ground bolt in from the wheel well. It makes attaching the ground cables far easier from both top and bottom. Be sure to clean the sheetmetal and threads well, then apply dielectric grease as Aaron Cake says to and finish it up with a Stainless Steel nut. Plus, you can put an Adel Clamp (Nylon here for non-conductivity) on the positive cable and secure it there too.