Ive got a 95 Z-28 with 113k on it. Totally stock. Automatic. Ive had it for 6 months and have put about 3k on it. It has always started and ran perfect since the day I bought it. One crank; then Vroom! The past week it has started acting up. When it is cold, or has been sitting for more than three hours, it cranks for a solid 5-7 seconds and then starts. I can shut it off and try starting it at any point within a few hours and it cranks once and starts. After 3 hours: crank crank crank crank crank Vroom! It's riving me nuts! I was wondering aloud about the optispark which it totally alien to me (points and condenser? no problem!), but it seems completely fine otherwise. I can nail it from a stop, a rolling stop, or at 50 and it reacts perfectly fine. No stumble, no cutting out, etc (but lots of rubber in the ozone . I was thinking if it were spark or fuel it would stumble at other times. It's almost like it loses fuel pressure after sitting an needs to pump the fuel back into the injectors. It's not leaking gas and the fuel pump isn't whistling or making wierd noises like it's about to crap out. It cranks over nice and fast so i'm leaning against a bettery/starter issue. I'm probably missing something stupid; hopefully someone has the magical answer on this!

 

That's how mine acts but my pressure bleeds off immediately. Check your pressure.


Posted from Camaroz28.com App for Android

 

Before you turn it to "start", cycle the key back and forth rapidly from "run" to "off" three or four times. If it starts easier, you have confirmed it's losing pressure rapidly after the pump primes for 2 seconds and then shuts down. Typically this problem is caused by a failing check valve in the fuel pump, leaking injectors, leaking fuel pressure regulator, or even the flex hose for the pump in the tank.

Once the pump stays running, the check valve in the pump serves no purpose, so it won't affect the way the engine runs, only how long it takes to start it.

 

I tried tricking the fuel pump by turning the key to run and off a few times; it did fire quicker, so you are probably right with it being the check valve in the fuel pump. There are absolutely no fuel smells from a leaky injector or line. I dread the thought of pulling the tank but would rather not pay someone to do it if I can help it. Am I playing Russian Roulette by just driving it this way for a while?

 

you can cut a trap door to change the fuel pump and its a very popular thing to do and I would if I hadn't already done so. If car is running fine after startup then you probably are safe for a while. I would check the fuel pressure and also check from time to time. If you dont own the setup to test they can be had for around $40 or you can get them at a few of the parts places tool loaner programs for a deposit(or test in lot and they will often not charge you but hold your id) If your pressure is within specs and not being eradic I would feel safer given your willing to put up with the extended cranking or the extra priming. A side note is pumps will fail premature if you dont have enough fuel in tank as they need the fuel to help them cool. Its recomended to not let it go under a quarter tank.


Posted from Camaroz28.com App for Android

 

my above statement is based upon it being the checkvalve in the pump. I wouldnt want a leaky injector and the fpr often will spit fuel into the vacuum line so when testing fuel pressure take note if any fuel is in the vacuum line.


Posted from Camaroz28.com App for Android