I've got an S4, N/A engine.

Okay, I've went through the FSM to check the vacuum hoses, wiring system, etc. and have tried to search for this. Haven't come up with an answer yet so here goes. I crank my motor, it will come to life and rev up to ~3000. It will soon proceed to rev down to around 2000 rpms where it then cuts off. If I push the gas pedal when it's revving down, it will bog down and die. The motor is actually on for about 5-10 seconds before it starts to rev down, which after that 5-10 seconds touching the gas pedal will make it die even faster. Any suggestions would be very much appreciated. I'll take each reply seriously and I'm very thankful for your time.

-Chris

 

So you still have the stock efi correct? Does it smell like it is running too rich? Does it fire up right away?

 

Fuel filter? If it's not getting enough fuel to run, that could be the result.

-=Russ=-

 

Doesnt fire up right away. It is an 88, stock fuel system. All that was done to it was just an engine rebuild using rotaryaviation.com's seals.

To start it up, I have to sorta clamp the fuel line, and then after it fires, unclamp it before it runs out of gas. I guess its just low compression that causes it not to want all that fuel. It has good injectors too, purchased recently (stock 460s). I also have the mazdatrix bleedoff thing that doesnt let pressure build up on the injectors after the car is off. Doesn't smell rich either.

 

Well I mean it'll run at 3000 rpms, but then it will slowly start to go down to try to idle, and then die. It's like it'll do the cold start process, but after it's done with the rev up, it doesnt know what to do and just cuts off.

 

What happens if you step on the gas right after it's started? Does it die out, or will it rev for a bit?

-=Russ=-

 

it'll go to ~3500-3700 rpms with the gas mashed in, ya know kinda rev some, but after that it'll bog down and cut off real fast with the pedal still mashed in.

And Edit: The fuel filter was replaced within the last ~8 months

 

Take that bleed valve bullshit off. I had one of those keep a car from running once...it did exactly this. Use a fuel cut off switch instead...it's easy to wire it up inside the car. With it, you won't need the bleed off valve, or vice grips.

 

you might also want to consider checking all hoses again...look at the air filter and everything around there...sounds like it couldl be one hell of a vacum leak..and don't step on the gas too hard ..if it is a vacum leak then you can run lean in an instant..too much air and not enough fuel..happened on my old Turbo II..intercooler hose poped off and blew the front rotor

 

k thanks guys for all of your suggestions. lol I guess i'll be ripping out that bleed off valve piece of crap today and running new hose in its place. i'll also go check all the vacuum hoses once more to make sure i didnt miss anything.

now that i think about it, that bleedoff valve didnt help at all when i had my leaky secondaries....

 

okay update on the car

still doesnt run

took my mazdatrix bleedoff valve fuel contraption off, now it wont even start. so i checked the hoses to make sure the hose from the fuel pump was in the right spot. i disconnect the hose, put it into a bucket to collect the fuel and turn the engine over. to my surprise, the engine would turn over but then cut off with the fuel hose off! and it's the right hose too, the one that goes from the pump to the solenoid city from hell to the injectors. it seemed like if air got into the system it was good. so i put the hose back on, and clamp it down so no fuel can go through. doesnt run. slightly loosen the lock nut so a little fuel can go through. nothing. i keep loosening and so on until fuel goes through 100%. nothing.


nothing, nothing nothing.

 

Have you checked for vaccum leaks thoroughly? Why don't you check the compression with a regular tester and see how much you have. Anything over 80psi, it will atleast hold idle I would think.

 

Step 1. Remove plugs, clean off.
Step 2. Remove EGI fuses in engine bay fusebox.
Step 3. Crank car over repeatedly to clear out the BS in the engine.
Step 4. Inject some oil or atf in the lower plugholes.
Step 5. Reinsert plugs, wires, and fuses.
Step 6. Be sure your fuel lines are on right. Supply from the fuel filter goes to the front nipple.
Step 7. Get inside the car, and wire up a fuel cut switch. Find the relay under the dash, cut the middle wire, attatch 2 longer wires to those 2 wire ends, run it somewhere you can reach, and put a toggle switch on the wires. Find out which way is on and off for the switch using a multimeter.
Step 8. With the switch ON, crank the car with the throttle partially open. The car should catch.
Step 9. Use the switch to cut fuel during cranking if it seems like it almost started, but didn't. IF/when the car fires up, flip the switch on quickly to restore full flow.
Step 10. Once you get the car running, do NOT let off the gas and let it die until all the BS gets cleared out of the engine. ONce it dies, it'll be hell to start again. I usually idle mine up ahead of time, out on the engine, so that I know it will idle on it's own once it does get fired up.

 

I had this problem with my freinds turbo conversion it turns out his main relay was toast. check your relays. it might be a good place to start!
especially if most of what kevin suggested doesn't turn out to work

 

i will have to agree with resurection here..you will also need to keep your foot on the pedal while you crank to let in more air to dry out all the BS..you could just be WAY flooded...make sure you have a fire extinguisher handy...not sre if you have a cat but it could be full..a presilencer can fill up with fuel too so get one either way..anytime you play with fuel you should have one anyway....Remember what SMOKEY, The Bear says"Only you can prevent RX7 Fires!"

 

appreciate all the suggestions, cat is about 1 year old... wouldnt think its clogged. I'll do what Kevin suggests, especially with the fuel cut off switch. that'll be going in tomorrow. if these suggestions dont work, i'll just strip the LIM and UIM off, and just start over from there. It may not be fun to go back and take things apart, but hey! anything's better than going to the MAZDA DEALER. they don't know what a side seal is... they think apex is a brand... i asked for a nut that connects the exhaust manifold to precat, and they give me an exhaust manifold to engine nut (which they charged 6 BUCKS for!!)

but anyways, thanks guys for all your help. it means alot to me

 

i di not mean that the cat is clogged...just full...full of gas that is

 

My guess - the in & out fuel hoses are reversed.
Initially the bleed valve will mask this.
Removing it kills fuel flow all together.

 

k.. checked fuel lines today, all vacuum hoses. i took everything off down to the engine, and started to assemble everything back with the FSM by my side.

After assembling everything, I started to crank my car and fuel shot EVERYWHERE. Had a crack in my metal fuel line on the solenoid rack from hell. So i took my UIM assembly off, and ran a fuel line from the small circular main fuel line thing on the driver's side to the primaries. That fixed the leak. Put everything back on again. Checked all connections.

But when I go to crank the car again, no luck. Tried unflooding procedures for about an hour... nothing. Tried ATF and MMO for compression, didnt work. I've been working on this stupid thing since January.

I am so burnt out from working on it. I think I'm just going to have to find someone in NC that will come to my house and fix my car. I don't have much money I could spend, 150 at the most? That's pushing it. I'm just a 16 year old. I've spent all my money on the rebuild kit and new parts, and still owe some money to my parents. I've got the engine to run a few days ago with my mazdatrix fuel bleedoff valve thing on, but it will run up to 3k rpms and then drop down to 2k rpms slowly, then shut off. With the leading plugs off, pulses from the rotors are loud and consistent. Running premix too, 14 oz on 3/4 a tank. I wanted to make sure everythign would be well lubricated. MOP disabled. 2 stroke oil is the TCW 3 or whatever certified oil.

I guess I just have to give up. I don't know what else to do....

 

I like that idea even if it turns out to not be the problem That's using your noggin. I doubt I woulda thought of that for a couple of weeks.

Any small chance you left the brake booster line off and created a large vac leak? Or, my latest screwup was installing some primary injectors and getting them cocked in the bores. The car would start up just fine but die just fine too. If I kept the throtte pushed it would keep running roughly. Took about ten minutes to figure out I needed to take the intake apart right away. Does not sound like your problem since you say the throttle stomping does squat for you..

 

Have you checked out the AFM yet? Read it out per FSM with a meter, eliminate it as a suspect...

Are you SURE you have no vac leaks? At the primary/ secondary bleeds...Oil metering nozzle stuff all plugged up good?

Is the CAS/ timing dead nuts?