Ok, so i'm driving along, at about 2,500-3,000 RPM's then randomly the tach drops down to zero. SO i figured well maybe my tach broke.. because i still have power and i can accelerate. Well when i come to a stop light the car idles just fine then, when i hit the gas it stalls out.

So after trying to start it multiple times. Had no luck. I opened up the hood and checked all the spark plug cables, unplugged them and stuck them back in. Tried starting again.. this time i actually head the car try to ignite. My buddy arrives and he helps me push start the car. To avoid going into the intersection we just push started it in reverse (don't worry no cars behind me) The car starts right up and the tach is working.


SO my buddy follows me home just incase.. well after about a mile, i'm going about 40mph, and the tach drops to zero. I give the car some gas, and it still accelerates, then it starts chugging and dies. Went through the same steps again.. checked the cables thought maybe a loose connection still wouldn't start. So i gave up and called AAA and they towed it for me.

So it's currently sitting at a shop, and i was wondering what may have been the problem, so i have some knowledge when talking to the mechanic.

Thanks,
-Matt

ps.. It's a 1985 GSL 5 speed, bone stock.

 

Trailing ignitor is dying or the wiring to it is loose. You will want to pick up an ignitor used as new ones are quite expensive (~$15 used, ~$185 or so new). This is something you could fix yourself in about 10 minutes with just a Phillips screwdriver.

The reason why the car died, is that the 84/85 cars have a fuel pump relay. This relay turns on the fuel pump only when cranking or if there is a signal from the tach/trailing ignitor. This is a safety feature so that your fuel pump turns off if say you are in an accident and the engine dies. The fuel pump shuts off so it won't be pumping fuel into a possible fire.

I would bypass the fuel pump relay and drive on just the leading for now. Order a spare ignitor or 2 on here or ebay and put it on when it get there.

 

Thank you so much!

Just two questions.

1. How do i go about bypassing the fuel pump relay?
2. If i'm running just the leading will it damage my engine?

 

The fuel pump relay is under the dash, driver side. Unplug the relay and insert a jumper wire. Use 14ga or so sized wire as the jumper wire needs to carry the full current to the fuel pump.

https://www.rx7club.com/showthread.p...uel+pump+relay

Running on leading won't hurt anything. You may produce some extra emissions and lose a tiny bit of power, but that is about it. You won't have a tach, so just shift by the sound of the engine. Good luck.

 

Excellent! Now if i don't want to spend money on a new ignitor i can just MacGuyver the ignition and drive home.



On another note i was doing some researching, i noticed one difference when i was trying to restart the car, compared to before.

Daily Starting: When the car fails to turn over, once i disengage the starter i hear the very quited low hummmm then a click.

now: the hum and click is completely gone..

so my guess is that hum is the fuel pump. Am i correct?

 

Yep, probably so. The 79-83 RX-7s ran the fuel pump whenever the key is on. So you turn the key on, hear the hum from the pump, and start cranking. I would save my money and get a used ignitor/do it yourself. The mechanic would probably replace both ignitors ($$), charge who knows what for labor, and so on. I have learned not to trust most shops with rotaries.

 

I had the exact same problem (tach drops to zero followed by stalling) when my Rx7's shutter valve(coasting valve) started going bad. The only difference is that my Rx7 usually would start back up pretty easy. I replaced the shutter valve and the stalling problem never returned.

I would do everything that gsl-se addict has recommended. I would also check the shutter valve. If you can get your car started, remove the lid to the air filter, place your finger over the small hole, rear driver's side of the air filter canister and see if there is any suction, there shouldn't be any.

 

I have a set of ignitors I will sell. $50 Shipped. PM me if your interested.

 

Ok so the mechanic called, he was able to get the car started.. but he said my battery is totally shot, and the alternator is weak. The battery part i believe, but the alternator i don't think so. Because i've always had a constant 13.5-15 volt reading when the car is runing, and about 12.2-12.6 when the engine is off. I mentioned to him about the trailing ignitor and he kept changing the subject and going back to the alternator and battery. So what ev.. i'm just going to go to the store, buy a new battery, drive it home, and hook up do my own volt tests, and check out the cables.


But i still have my money on the trailing ignitor. Because what gsl-se addict described is exactly what happened to me.

hopefully the car will make it home ...

Thanks again!
-Matt

 

I don't buy the batt/alt thing. If the alt was shot, sure a similar thing would happen once the battery got low. But if that was the case, you wouldn't have been able to crank/get it started again. I doubt you need a new battery either. With the alt charging though, it should run even with a bad battery. Mechanics will usually start replacing stuff until it is fixed. First it will be battery and alt, then probably new belts with the alt. If that doesn't fix, then he will put on 2 new ignitors, possibly coil, plug wires, and so on.

I would just make a jumper, go to the shop, plug it in, then start the car and be on your way. You can get the alt/battery tested at most any autoparts place for free.

For the jumper, just grab some 14ga wire or something, cut to 2 or 3 inches long, crimp male spade connectors on each end. I will look up the wire colors to put the jumper across so you know for certain where the jumper should go.

EDIT: Connect the jumper from a BW (Black w/ White stripe) wire to the LW (Blue w/ White stripe) wire. Once connected, you should hear the fuel pump hum when you turn the key to the 'ON' position.

 

Ok, so i went to get the car... The mechanic said.. well the car keeps dying so i don't know whats wrong with it... i'm like.. uhh ok... give me 5 minutes... So i start it up, on the OLD battery and the OLD alternator.. it starts up.. just as it starts to warm up.. tach drops to zero and car dies 30 seconds later. So I then i pulled out my MacGuyver'ed wire (Picture hanging wire with black electrical tape around it) and jumped the relay... The car started right up without any problems... Drove it home without a hitch. So all is good. But i am going to take that idea and install a switch to disable the fuel pump (for security reasons)

Thank you all so much for your help... you saved me a butt load of money! (gsl-se addict, and rxcalibur)


SCCAIT7 - i'm going to talk to my dad about the ignitors, but first i'm going to trace all the wires for a lose connection. But if i need them, i'll be sure to PM you.

Thanks again,

-Matt