Ok, so I have a 1996 blazer 4x4. I've had problems with hard starts and found it was due to my fuel system having a leak somewhere. When I turn the car to the "on" position the fuel pressure goes up to 60psi and then instantley drops back down to 0. When the car is running at idel its at 54psi. So I decided I would try the fuel pressure regulator first. I took the upper intake off and didn't see any signs of leaking. So I hooked the fuel lines back up and turn the key to the "on" position. When the system pressurized I still did NOT see any leaks. So I now I assume thats not the problem. Now as far as the spider assembly I didn't see any leaks and the truck runs fine when driving so I assume thats not the problem either. So does that basically just leave a bad fuel pump? Also while I still have the upper intake off is there anything else I should test/look for? Any help would be great! Thanks!

 

96+ Fuel System Diagnosis

Run through the tests that you can in the thread above. You can also pull out each of the individual injectors and check them for leaks while the system is pressurized. It is quite possible that it is a stuck poppet nozzle and a bad injector. If you were to pull the plugs, you should be able to see evidence of this on the plug as well.

How fast does the pressure bleed off to zero? One minute, two?..

 

The pressure bleeds to zero in less than 10seconds. I'll go pull the injectors one by one and check to see if there leaking. I thought if there was a stuck poppet nozzle it would cause the car to run rough? My blazer seems to run fine once its started, just has a hard time starting.

 

It should. Just listing the possibilities.

I do suppose it is possible that the FPR could be at fault, leaking through to the return line. You could try disconnecting the return line and plugging it (although I am not sure what the threads are at the return line connection).

 

Which one is the return line? The bigger or smaller one.

 

Smaller.

 

Thanks thats what I assumed, just wanted to make sure.

I didn't get a chance to test the injectors, I will do that tomorrow and give an update.

Also I forgot to mention, when I turn the key to the "ON" position I can hear the fuel pump prime, but it never turns off. It just keeps running.

 

That is odd, it should be timed by the PCM... It reaches the proper pressure (~60psi) though right...?

 

Yup, it hits 60psi, but as soon as it hits the 60 it starts bleeding off.

 

So another person on s10forum suggested to isolate the fuel pump. So I put a rubber hose on the supply line and put a bolt in the other end. I clamped both ends to make sure there would be no leaks. I then turned the key to the "ON" position. The fuel pressure rose and then dropped right away like its been doing.

Now somebody mentioned theres a check valve in the fuel pump. Could this be the problem? If so is there any easy/cheap way to fix this or do I need to replace the whole unit?