LTX_OUTLAW

hey guys i'm in need of some great help recently my 93 formula has been running on the rough side while i am driving the car it seems to hesitate randomly or even completely shut off with out any notice some days it runs great and some not so well and sometimes it takes a few minutes to start after driving for a short distance i recently replaced the fuel pressure regulator, fuel filter and even the fuel pump assembly the car has a msd distributor that has been running great since i bought the car right now i am just stuck on what could be possibly wrong with the car and any advise or troubleshooting procedures or where to start looking would be a great help thx

redline9570

Any tailpipe smoke? Pull off the fuel rail and check to see if all the injectors are working. On top of this page there is a procedure to check opti since yours is non vented type. Bad coil which you can also test. No codes thrown?

LTX_OUTLAW

Well all of the injectors are working properly and also it's a msd vented opti and there are no codes present Coil wires and plugs all are new and it usually happens at random moments I can be driving at highway speeds or in town errands just a example a few weeks me and a co worker went to the track It drove great and then I turned it off about 20 minutes later I decided to run the car and it ran great but when I got done I parked the car for about 15 minutes to get ready to head home it would not start I sat at the track for about 30 minutes and then it finally started? Lately that's been the trend whenever I does it may take a few minutes before it restarts but something else I noticed when it does die sometimes every other starts I didn't hear the pump? Is there a relay or switch that may be bad? I just about replaced almost all of the major components relating to fuel

redline9570

That sounds like vapor lock, http://shbox.com/1/evap_system.jpg got all the info for fuel pump etc..4th Gen LT1 F-Body Tech Aids

slick1hunting

I would check the fuel pressure and drive with the gauge taped on window. Look for a drop when having the issue as well as any quick leakdown after turning car off and look for pressure at key on. If you have not done the coil cooling mod(and icm) I would also do that(spaces coil off of head and helps prevent it from overheating and heatsink issues. I would also look for any arcing underhood in the dark(car heated up nice as well as a cold start) pay particular attention by headers or exhaust manifolds and spark plug boot. Might also want to look at opti wiring harness for corosion and give it a little dielectric grease. If none of that solves it or points to anything I would test the coil and icm and opti. Definately verify fuel pump primes on the key on non starts. I recently had the pcm ignition fuse in the panel not make a good connection from corrosion in my car and the pump would not prime nor injectors fire( that may be worth a quick look as well) Is vats tuned out of your pcm? That also controls fuel and could prevent startup.


Posted from Camaroz28.com App for Android

Fatdog2

What codes is the car throwing?(Providing you do own a code reader I hope.It plugs under the dash for problems).It's pretty cheap.My02.

Skedaddle

He has a 93.... does not require a code reader. He can flash the codes on the SES light by shorting the ALDL pins. In post #3 he indicates there are no codes. But a sudden shutoff could be an issue with the cam position sensor signal from the Opti, or a problem with a short or open in the ICM circuit. Both of those would set codes.

When you installed the MSD Opti, did you loc-tite the rotor screws?

LTX_OUTLAW

well guys the news is in apparently there is some sort of diode or electrical circuit inside of the ecu that went out and that is tripping the fuel pump relay which in turn killing the pump??? a local performance shop here in town ruled that to be the problem and said that the easy fix was to run the wire as a constant switch hot so it won't cut off while the switch is on (not too sure how safe that is but ok) if someone has a ecu for a 93 that would be great or any recommendation's on any aftermarket tuning companys like fastchip or pcm for less that can maybe offer a slight performance gain???