i have a 1994 rx7 that me and rotorsports racing of kannapolis, nc have troubleshooted for near a year. i need help. i took the car to rotorsports in sept 08 because it stopped starting hot and when it did run it was fluttery and super rich. 10.0 on AEM from idle to interstate driving. i assumed compression trouble.... well since the motor has been pulled and has brand new rotor housings and side housings bridgeported by rotorsports, fresh rebuild with one piece ceramic nrs apex seals, gt4202r garrett turbo with custom manifold and downpipe, new powerfc, new wiring harness, new battery, hks twin power, etc... needless to say ive got a fresh motor that has been pulled back out twice now due to the fact its having the same issue it was back in september. wont start and when it does its not driveable because it wont stay running. ive got 50psi of fuel pressure, spark plugs are firing, but wont start. we both are confused on what would cause a car with a fresh rebuild with great compression, spark, and fuel, and much more can act this way. what did we miss??? I MISS MY CAR!!! ready to drive it again.

 

when you say "when it starts it wont stay running" what are you doing to get it to start? I know it seems stupidly simple to ask, but will it start if you supply an outside fuel source(i.e. carb cleaner, brake clean, starting fluid, etc.)? if so then your problem is fuel related. If not then its either spark or compression. Sometimes it helps to forget everything you've checked and start with the basics. Systematically eliminate entire systems as the problem in the simplest ways possible.

 

Sounds like you may have a bad injector that is locking open.

 

it will start first try with some idmitsu pre mix squirted down the primary vacuum ports on the uim. but we cant tune it to an idle because it acts like it wants alot of fuel. when we give it more fuel it then dies immediately. then ur back to square one. urghh. for compression..on a basic compression gauge with a bleed of, to allow a reading that fluctuates rather than stick on the highest reading, it reads 70psi. the gauge is said to read about 15 to 20% low due to the bleed off. compression is good. ive got a new stock in tank fuel pump to a surge tank and out through an inline sx 18203 fuel pump to an aeromotive fpr under hood which ive got set to 50psi. it then goes to fuel rails which both are top feed converted rx7store.net rails(brand new. with 2 brand new 850cc primaries and 2 brand new 1600cc secondary injectors that return back to surgetank then returns to stock tank. the injectors are plugged into a brand new wiring harness which is connected to a brand new apexi power fc which was professionally installed. when pulling out the plugs while still connected to new plug wires and turning over the engine with injector fuse pulled it throws huge spark thanks to a new hks twin power ignition. i'm lost thanks for the advice. all help is greatly appreciated.

 

What are your pulsewidths when you are trying to get it to idle?

 

i cant quite remember. i believe 6 milliseconds. what i do know is it was way to long and my vaccum is suffering.

 

That's about 3x the fuel then is required at that fuel pressure on 850CC injectors.

It just sounds to me like the tune is completely and totally out to lunch.

 

Hi,

You state that your fuel starts in the tank, passes into the swirl pot (surge tank we call em over here) then on into your inj rail and through the FPR, then back to the surge tank.
If I'm reading this right, the FPR cannot work as its return is seeing full pump pressure. (return needs to be to fuel tank)

This would explain the rich running?

Jonathan Fennell