96 fuel trobleshoot help.

[czocco]

1996 vortec v-6..CSFI..

Fuel filter replaced...no codes...good spark and plenty of air.

It wont start after sitting too long (overnight).. I have to put gas (or carb cleaner) in the throttle body to get it to fire..and run.

It has been slowly getting harder to start in the am...and now its come to this.

Fuel is my issue...and Im going to check the pressure tommorow when I buy a gauge...BUT!!!
while the gauge is attached at the fuel port on top of the intake..

Do I check with the ignition in the ON position?...(ya know..when the fuel pump runs for a few seconds, appears to build up pressure then cuts off)

>>>>>>>>>>>>>>OR>>>>>>>>>>>
while the engine is running?

MORE IMPORTANTLY!!!...if the pressure is good..do I look at the regulator and the fuel meter body (PULL the intake?) or do I still look at the pump?

If the pressure is low...do I eliminate the regulator and everything under the intake? and consentrate on the pump?



ALSO.....In the on position..I can get a short squirt of fuel if I depress the valve stem on the fuel port..then just a dribble.....But when shes running (although be it rough) I get a good stream of fuel that hit the firewall....Is that normal? should it be hitting the fre wall with just the pump on in the ignition on position?

[Mikado14]

Ok, now you have 2 threads going for the same question, I will repeat.

Both, pressure should be measured with the Key on and engine off and it should not bleed down, at least an appreciable amount.
It should be checked also when it is running.
There is a max and a min. By checking engine off, you will see the pressure that builds up, if it goes too high, the regulator is usually the culprit. When it is running, if it is below the minimum, suspect the filter or the pump in that order.

If the pressures are fine in both scenarios, then come back.

Oh, relieving the schrader and looking at the "squirt" is not a method of troubleshooting. It can be dangerous, (my opinion) and I have never met a person that could tell the pressure from the "squirt".

[BlazerLT]

^^^What he said.

This is a pump or a fuel pressure regulator problem.

[Jeremy-WI]

60-66 psi key on engine off, pressure should not drop after pump quits. At idle pressure should be about 5 psi lower than with engine off, a good snap of the throttle should bring pressure back above 60. After the vehicle sits overnight, see if it smells like fuel through the throttle body, if it does smell, you probably have leaking injectors or fuel pressure regulator leaking through its vacuum port