i need to know because its between the fuel pump or the regulator....half the time when i go to start my car i have hold it over cranked for a few seconds then when i release and try again it fire's right over im really not sure so i was looking for some ideas, yet some times i can get in my car and it fire's right away, any idea's?

 

mine does that too, although i also have the ses p0442. my car starts right up cold but not hot it will do what you described... i thought it might be the filter although its way to cold to change it here

 

If you let it sit with the key in on for a few seconds before starting (lets fuel pump press up line) should start right up. If you have a leaky fuel system, sometimes it won't start on the first try, as you may not have given it a second to press up the fuel lines. By leaky, I don't necessarily mean external leak, it could be leaking back to the tank, but fuel pressure is down nonetheless.

 

ok 1st take a pressure gauge and connect it to the fuel rail..put ignition key on and engine off and observe the reading. my 95 camaro was supposed to be 41 to 47 psi. if the readings are low.then its the fuel pump or filter. if the reading is low,then the pressure regulator is bad

 

I love it when old posts get pulled up, because a noob wants to post, and then doesn'tquite answer the question...

 

This is how it works:

When you turn ON the ignition switch, thePCM enables the fuel pump relay which powers the fuel pump ON. The fuel pump remains ON as long as the engine is cranking or running and the control module receives ignition reference pulses. If there are no ignition reference pulses, the control module shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops.

The fuel tank stores the fuel supply. The electric fuel pump supplies fuel through an in-line fuel filter to the fuel injection system. The pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pressure regulator maintains the correct fuel pressure to the fuel injection system. A separate pipe returns unused fuel to the fuel tank.

This is how to test it:

1) Connect a Fuel Injection pressure gauge (available from most part stores) to the test port on the FI rail (similiar to a tire valve). Be carful as fuel under pressure may spray out.

2) With the key ON & engine OFF (cycle the key ON-OFF several times as pump only runs for 2 seconds) the pressure should be 41-47 PSI. (If NOT: weak pump, dead pump, or no power to pump)

3) Turn key OFF, pressure should NOT drop more than 1-2 PSI and then hold steady. (If NOT: fuel line leak, injector leak, regulator leak, fuel pump check ball leaking)

4) Let engine idle, pressure should drop 3-10 PSI from the reading in step 2. ( If NOT: bad pressure regulator, vacuum leak to pressure regulator.

5) WOT (car accelerating at full throttle, pressure should hold @ 41-47 PSI. Good to have two people, one to drive and one to watch gauge (If NOT: dirty fuel filter, weak pump, bad pressure regulator)

 

I have a 95 camaro with the 3.4 that runs terrible, thought it might be the fuel pressure regulator and I found this thread on google. Car was dying at every stop and had no power, sounds like it is missing but I have spark and once in a while it will run right. I followed the directions above and was wondering if someone could help me figure out where to start.

Fuel Pressure:
-idle 36psi
-Tap the gas rises to 42-45psi
-WOT between 40 and 45 (needle fluctuates wildly between the two, like a blur)
-remove vacuum line, psi rises 5-10 psi as it should. No fuel come out the vacuum line so the regulator should be good?
-*Turn off engine and the pressure drops rapidly to zero, takes about 30 secs to lose all pressure

Based on the info in the previous post it could be injectors, fuel pump check ball, or weak pump?

a little background that may or may not help: When I got this car I looked under the car and the fuel filter seems to be semi new, its all silver and no build up of dirt, its not a GM filter, also the line from the filter back to the tank has been replaced with a plastic after market line (same type I used when I did my F250 fuel pump) and the muffler (below the tank) had been cut (for gas tank removal?). One would think they replaced the fuel pump but you never know. I put some lucas fuel treatment in, that made it run a little smoother but still ran like a dog, stumbled on acceleration etc. The next day it was suddenly running better, like no miss, good power etc, I hammered the throttle several times trying blow out any build up in the injectors and what not, next start it went back to running crappy. Parked it for several weeks till I had time to mess with it, today I start driving and notice it is no longer dying at idle/stop lights but still runs poorly. So I went and used autozone's fuel pressure gauge to get the results above. Any help or input would be great! Thanks.

 

a failing fuel pressure regulator will do that and a failing ball valve in the pump. stuck injector can cause a fall but i dont know if it would be that fast. i have had a bad regulator before and as soon as i turned the key off it would start dropping. this thread is 5 years old so i may just start a new thread with your post. have a look here at 33 and 34 on the list http://shbox.com/1/how_tos.html

 

Thanks for the response and the link. The regulator isnt leaking though at least not that I can see or smell. I'll see if I can narrow it down with the links you provided.

 

So I followed these directions from the link

"Watch your gauge as you jumper the prime connector. When you have good pressure remove the jumper and clamp off (or use shut off valve) the fuel supply line (3/8 pipe). If pressure holds, you have a leak on the feed line somewhere before it gets to the clamp (or shut off valve) or at the check ball in the pump. If it still goes down, release your clamp (or open shut off valve). Pressurize the system again, then remove the jumper and this time clamp (or shut off) the return line (5/16 line). If pressure holds, then the regulator is faulty. If pressure does not hold, you need to locate leaky injector(s). If you can't tell a leaky injector from reading the plugs, you can look and see if injectors are leaking by removing the fuel rail screws and pull the rail and all the injectors up, so you can see under them. Leave them over the injector ports. Pressurized the system and look under the injectors to see if any are dripping."



Pressure dropped with supply clamped and with the return line clamped, so I took the fuel rail apart (what a *****) and looked for the injector leak, was really hard to see the back injectors since the intake is on and they are so far back by the firewall. Appeared that number 5 (passenger side, closest to firewall) was dripping. Took all the injectors out, cleaned them up, lost an O-ring, and tested them for Ohms, all had 12. Connected them to power, all clicked. Dont know where to go with this now....