Ok.. heres the deal... I have a 95 Z with 72XXX miles on it. Its getting colder here in Indiana and I noticed its getting harder to start. It cranks and cranks and cranks and will cough and cough and eventually start to fire. It started getting worse. A couple weeks ago it took solong to fire it ran the battery down. Finally get it to start and I tookit straight to the dealership I used to work at. They checkit out and tellme my fuel pump is weak and my opti is toast. I go and checkit out.. sure enough opti is done... so a new opti and water pump get put on. Go to pick it up and they tell me that its still hard tostart. Its at best showing 40lbs of pressure when it kicks on. It still takes forever to start and onceit does it runs ok unless you step on it.... then it just falls flat on its face. So my question is... Is it the fuel pump or the regulater? Ive had fuelpump issues before but usually once the pump goes bad its done... never had one just struggle like this. I dont want tojust throw money at it chasing the problem especially after just replacing the opti and water pump

 

If the check valve is stuck open in your fuel pump, the pump will not hold prime while starting. Test it with a fuel pressure gauge and make sure after the pump primes (runs for 2 seconds and shuts off) that the fuel pressure doesn't drop to zero quickly. Stock fuel pressure is 41 - 47 psi with the vacuum line removed from the regulator. You also need to check if the pressure drops under load. You can temporarily tape the gauge to the windshield and drive the car. Monitor for dipping fuel pressure when accelerating. If the pressure dips, your pump may be getting weak or you could have a clogged fuel filter.

 

yea it definetly drops under a load... don't even need a gauge to notice that... brake torque it and it falls flat on its face... fuel filter is brand new so i can rule that out. I was pretty sure it was a weak pump but i didn't want to just throw money at it and cut a hole in the trunk...so ithought ishould check with the f-body gurus on here first.

 

ok... ordered new walbro 255 from racetronix.. installed it last night. Hooked everything back up...keyed it up checked for leaks...none...hear the pump kick on. Turn the key.... crank crank crank crank... cough...crank crank.. cough... crank.. nothing. keyed it up a few moretimes andstill the same result it just cranks and cranks with the occasional cough. after i stop cranking it will continue to sputter a few more timesbut nothing. Im about ready toshove it out of the garage and set it on fire. new opti..new coil.. new water pump..new fuel filter.. new fuel pump and still wont start.

 

Check your fuel pressure to see if it's coming up the 41 - 47 psi with key on (prime only).

 

ok checked the pressure.... primes to 48.... after thepump primes it drops to 39 and stays. checkedit a few times and comes up the same everytime (give or take a pound). crank and crank and crank and slowly fires up and gauge stays at 40-41 drops a bit under a load but not much. under a load the car stumbles but the gauge doesnt move. shut the car off and the gauge reads 33 and holding. got me stumped

 

Sounds like your fuel pressure and pump are fine. Try starting it with the gas pedal to the floor (flood clear mode). This will provide less fuel during start-up to see if the hard start is due to flooding.

 

tried that before the pump swap in my many attempts to get it to start... no real difference. one thing i forgot to mention...not sure if its related... after cranking it over every so often it will cough and cranklike usualbut when i stop cranking the car will continue to sputter and cough backfiring for a few seconds then stops.... i dunno im about fed up with it...gonna swap out spark plugs tommorow morning... maybe theywere fuel fouled or burnt with so many attempted starts on them

 

put new plugs in and its still hard to start... i give up

 

traded it in on a gtp.... thanks for the help guys