I have a 91 Z28 L98. Yesterday I saw the kids that have been shoooting my neighbors mail boxes drive by in a little honda and jumped in my Z and was going to try and catch up to them and get a tag number for the cops.

Any who, I only got about 1/4 mile down my road and the car cuts off. I wate a sec and try to start it and I hear a loud pop, I assume it's a backfire.
I wate and try 2 more times and it turns over but dosen't start. I push the car back into the drive way and begin to lower the fuel pressure (I was going to do that right as the punks drove by) I get it back down to about 42 PSI with a vac hose un pluged from the plenum. (I have 26lb injectors fwiw) I kept trying to start the car and it would start up for a few seconds and then cut off. My dad came out and we were checking all the vac lines and he unpluged one next to the radiator on the driver side and I tryed to start it and it fired right up. he pluged the hose back in and nothing changed so I checked the pressure again and then turned it off and removed the fuel pressure guage.

This moring when I was going to leave for work I started it and poped it into reverse and it cut off. I started it again and just wated for a bout 30 sec and it cut off, so I drove another vehicle to work.

A few min agao I was trying to get it to work again and it starts right up and idled at 1000 rpm for about 50 sec and then I start to hear a noise that sounds like when you get a static shock and then the car cuts off again.

The car was runing fine untill yesterday (a little rich) but fine. I have recently replaced the 02 and intake temp sensor and reset the min idle to 400rpm in drive. Sorry for such a long post but can anyone help me get this thing rinning right?

 

If it's cutting out soon after you start, it could be the oil pressure switch is going bad and cutting the fuel pump. Does it get poppy and shaky like it's going lean just before it cuts out?

Are you describing a snapping noise from under the hood before it stops? Maybe you have a bad ignition short somewhere?

 

yes it gets shaky when I hear the snaping noise and then the snaping gets more frequient and shakey and the car dies. I did notice the oil pressure looks good from the tachometer guage.
I have a 6al ignition and new wires and just recently replaced the cap and rotor.

 

What I'm thinking is that your fuel pump is shutting off.

I believe the gauge is fed by one sender and the switch which controls the fuel pump is seperate.

 

I just started it again and it ran for a few min but was stil making the snaping noise slightly, it sounded like it was coming for the distribuiter area. I kept an eye on the fp guage and it kept constant pressure between 44 and 45 psi with the vac hose disconected from the FPR

 

I just took the metal cover over the distributer off. The one that screws into the back of the plennum with 3 screws, and there was no more snaping. I guess it was somehow shorting out one of the wires. going to take it for a test drive and see what happens. I'll keep you posted, thanks for the replys TPI blazer

 

Just a couple observations...

First, the auxilliary oil pressure switch cannot shut off the fuel pump. It is installed a a secondary, redundant power supply to the relay. It is not a "safety shut off" as some people misunderstand. The schematic shows that clearly:




Second, the plenum extension trim cover is actually plastic, although it is painted with a metallic paint, so it might be slightly conductive. At 25KV, it doesn't take much, so that may be related to the problem. If removing it soves the stalling, the problem is not the trim cover, but the ignition secondary wires.

I'm thinking that you'll need to split the system and determine if it's fuel or ignition related the next time it stalls.

Good luck tracking down the shooters, too.

 

is there any reason why u are runnin 26 pound injectors? Is this a stock L98 or no?

 

thanks for the diagram Vader,
The plenum extention sure feels like mettal, it is even polished. well I found that the accel wire running from the distrib to the coil pack has a split in it and since taking the extention off has run fine.

to 86copchacer, it's not totaly stock. I have 52 mm TB, ported plenum and SLP runners, high flow base plate roler rockers and 26lb injectors. smog deleete, MSD ignition and Accell wires. SLP shorties and catback with maganflow muffler, 3.42 rear, SFCs, ADJ panhard bar, LCAs, LCA reloaction brackets, B&M shift kit, sportlines, koni yellows and a poly bushings kit. oh yeah, and C5 brakes

The previous owner did all the engine work and I have done the suspension. He told me that he had a custome chip burned for it too.

I'm still learing, this is my 3rd third gen and I want to eventualy swap a LS1 in the Z when I have more time and adequate funds, Only 19.

 

You mentioned pulling a vac line and it started.
Check into the fuel tank pressure control valve. Maybe your not getting air in/out of the tank causing your pump to cavitate (staticy noise just before it dies)
If it does it again, pop your gas cap right after and see if you hear air rush in or out. Might be a clue to whats happening.
There were several good posts on it previously.

Ps Vader,
That diagram needs to be made into a sticky post.
I'm tired of arguing the point