I was wondering if this could be my hard starting problem on my 99 Blazer. I have checked the fuel pressure and it's good, I also have checked it with the ignition off and it holds around 50lbs for quite awhile. My problem is that it starts hard everytime. Hot or cold, just running or sitting all night. It's worse when it sits for awhile. To get it to start today I had to prime the fuel pump 5 times. Key on and off 5 times then it started, otherwise it will just turn over and over and spit and sputter but won't start. The fuel pressure is good so the last line of items is the spider injector poppit thing. It have 134k on it and I know it has never been changed. (My fiances father bought it new) What do you think?

 

You need a fuel pump. These need to hold at like 62 for fifteen minutes. Everyone has there ideas on this. This one is mine. You can pop the plenum and look for leaks all it takes is a 10mm deep socket. You look for shiny gold spots, that would be were gas is spraying and washing the grime that's supposed to be there

 

So 53 PSI running is too low? The fuel pressure stays up when I try to start again (As it does not bleed off immediatly) and it still starts hard. I feel like this can't be a fuel pump issue if the pressure is holding on a restart and it still starts hard. Unless 53PSI is really that low....

 

If the pump is weak, it not enough psi to activate the poppets in the injectors. What's the running psi? Holding pressure or not, pump must push a minimum of 55+psi to even activate but still will sputter unless at 60 minimum running or at key off and hold no less than 55psi after needle settles...

Not enough pressure to start is one of the biggest reasons for long crank on these, until they no longer are able to start, then your stuck.

 

Here is a video I took of the fuel pressure gauge while it was running.

 

Good enough video, though only the end or last couple seconds where the gauge was actually readable was the most helpful. I do understand how tough it is to hold the phone/camera while doing the test.

According to the video, it almost sounds as if there's a vacuum leak though, which could also affect the running of the engine. These engines are very sensitive to vacuum leaks, especially at the plenum. I see the stutter of the engine too. Overall pressure is still low though, even throttle snaps bring it up some (which is supposed to happen) but too low of pressure will cause that stutter and rough idle or hesitation upon acceleration.

Do you hear the hissing (vacuum)? or was that just the video quality? If you do hear hissing, look for vacuum leaks or even try replacing plenum gasket...thoroughly clean both mating surface before sealing back up. You could also throw a vacuum pressure gauge and verify mechanically....you would look for a nice steady needle, no jumpiness or bouncing after idle stabilizes.

Also, thread title....spider injector? no I don't think there's an issue the injector system itself

 

sounds like my truck when I bought it and it was the spider.

 

for the test you need to do key on engine off, level should be over 60psi, then key off and it should hold above 50 for 10 minutes. cuba, his is a 99

 

GM does not publish any engine running fuel pressure specs for this engine. There are far too many variables involved such as engine condition, elevation above sea level, etc, etc. When the ignition is initially turned to the RUN position, (do not crank the starter) the fuel pump is activated for ~2 seconds and shuts off. Fuel pressure must be tested while the pump is activated. Pressure must be 60psi to 66psi. It must remain above 55psi for at least 10 minutes after the pump shuts off. If it passes both tests, the fuel delivery system is operating properly. If it fails one or both tests, pressure and leakdown must be tested at the fuel filter outlet to determine where the problem is. All pressure and fuel flow must end at the tester. While the pump is activated, pressure must be 73psi to 108psi and it must remain above 55psi for at least 10 minutes after the pump shuts off. If it passes both tests, the pump is fine and the problem is inside the plenum. If it fails one or both tests, the problem is inside the fuel tank.

 

Well the rough idling issue was a vaccum leak. That is now fixed and it idles nice and smooth now. The only issue I have is that it's hard to start. When it starts it doesn't rev up to cold idle it slowly works its way up from probably 500 rpm. Its hard to even hear it start. It's hard to explain. It doesn't act like it just started, it comes to life weak i guess. I can mash the throttle and get WOT running down the road and to me that is a better indication that the fuel system is working properly than some numbers that apparently GM won't even release? WOT uses a lot more fuel that idle. So why would the fuel pressure not be sufficient for idleing but fine for WOT? I feel like its a fuel metering problem. If it has enough fuel pressue for WOT then it should have enough to idle. That's my feeling anyway. Am I wrong here? It makes sense to me...