I cant get my car to start up i just put the motor back in everything is the way it was, CAS is fine injectors get a sirge of voltage when i try to start fuses and everything look fine something im missing?

 

Injectors always see voltage, it's when they're pulsed with 'negative' that they fire. Check your EGI fuses (under the hood on the drivers strut tower) and then the 'Motor' fuse inside the car's fusebox, Also, try priming the fuel system by jumpering the fuel pump connector (located near the passanger strut tower, yellow plug, two pin) Double check your AFM/plug wires/CAS/etc, if still no go, try to get someone to hold the AFM flapper open slightly and try again, perhaps there's a bad vac leak somewhere.

 

jumpering the fuel pump connector?

 

it doesnt even try to start just spins no spark would that still be a vac leak?

 

It pressurizes the fuel system (usually after you've had the engine apart/out of the car, the system is obviously depressurized/fuel isn't in the lines, you jumper that connector and it runs the fuel pump so that it's pressurized, basically priming the fuel system so no air is left) Be *SURE* to remove that jumper (just a 2" peice of wire with 2 crimp male ends on it) before going anywhere, if you were to get in an accident the fuel pump wouldn't shut off!

 

does the car know when theres no fuel not to spark? some one said the CAS wont spark if theres no fuel

 

nope, it doesn't....it should still spark even if you aren't getting fuel. do you think youre not getting fuel or do you know it? What have you checked/tested so far?

Four main things to check--fuel, air, spark, compression

Pull the plugs and see if they are wet. While the plugs are out check compression. see if you can smell fuel in the engine. If not, then check the whole fuel system before you go anywhere else. Make sure the fuel pump is coming on when you go to start it. Once you know you have fuel getting to the engine, go on to the next--make sure your afm is plugged in properly. That is the big thing with air--the afm. a stock rx7 will not run without the afm unless you have a standalone running the engine. Also--tell us NA or tII, year, and what mods?

Once the afm is ok, check for spark. once spark is cool, if it still doesnt start, you might look at your ECU.

Oh, before all of this, double check all your wiring and connections. Just thought about what you said about putting the engine back in, and more times than not, we miss something simple.

 

The CAS controls fuel and spark, and is the only thing that will trigger them, it doesn't really look for conditions such as if they injectors have fuel (as it assumes the fuel pump is running already)

 

Yeah ran the fuel pump the sec injector rail isnt getting fuel so probably that might be my issue still no spark though very weird. I was thinkin I fried my ECU there was some smoke by the battery a few weeks ago when i had to roll my window up. I have a 87 GXL only mod is exaust which i got a week before the engine mishap alwasy happens that way =/. Thanks for the help appreciate it no one has been able to help much.

 

after some investigation here i found that the fuel is making it to the rail but the valve with the vac line on it is not opening to let the fuel in, should that be open all the time free flowing the fuel? Would this mean vaccum leak?

 

I'm willing to bet you have your fuel lines on backwards.

 

is it supposed to go to the injectors on the engine first then through to the secondarys then out?

 

Yep, just follow the picture (the blue lines, ignore the rest)



Sorry scott, swiped your pic

 

ok--the second rail doesn't come on when you start the car. your secondaries come on as you get up in rpms 3800-4000. I have seen people in here talk about starting and driving their cars no problem without the secondaries coming on. As for the ECU--it is nowhere near the battery. ECU is under the carpet in front of the passenger seat. Smoke near the battery may have been the leading coil. thats the closest thing to the battery that could be the problem here. I would get a multimeter and start checking the coils. Refer to the FSM for the specs, I am not sure off the top of my head what they should be. Or just pull a spark and place the end of it near some metal. Have someone turn over the car and see if it sparks. Either way, I dont see how that smoke would have been connected to the ECU.

 

Yeah fuel was on backwards still not spark im gonna check the coil when i get home. Should i hear the fuel pump when starting the car?

 

Hey Sonic,

I hate to do this, but when voltage is applied, THEN the injectors open.

SO its the positive pulses that cause the injector to fire, not the negative.

Jarrett

 

This is going to be a field day...

 

hows that?

Ive checked it! I put pressure to an injector and pulsed the injector with 12 V. Only with voltage applied did the injector flow!

Jarrett

 

 

Okay, I understand what he was saying...

There is 12V on one side of the injector. But there is no ground applied to the other pole. So there is no complete circut for the 12V to make. That means that even though 12V is being applied to the injector, if you put a multimeter on both poles of the injector, you wont see voltage.

Once the ground is applied (or pulsed) that completes the circut and actuall APPLIES the 12V across the injector and completes the circut.

So in essence, he is right, the ground completes the circut. But the injectors are opened by 12V.

Jarrett

 

So to speak.

 

The engine uses both coils when the engine is running right so if one didnt work it would still attempt to start wouldnt it?

 

thats right fuzzy--you have a leading and trailing plug in each chamber. They are both used equally at the same time, unlike the injectors at lower rpms. It will still try to start of one coil is bad. But I don't know if it would actually start. I have heard of someone driving with only one rotor giving power, but for different reasons.

 

yeah mine isnt even trying to start it very weird.