you could have a bad check valve inside the pump its self. or a leaking down injector. check around the injectors after you turn the key forward to see maybe if one of the orings are weeping.

 

Thanks. I emailed Airtex products to ask them about the pump.

http://shop.advanceautoparts.com/we...UE3-_-VALUE4&ci_src=14110944&ci_sku=20771757-357578&vehicleId=357578#fragment-4

Has anyone else used this pump?

Thanks, George :LS1LT1flag:

 

Hate to bring this up, but could the connection where the pump connects to the sender assembly be leaking. Heard of this happening before.

 

Maybe, but would I still have that good of a fuel pressure when the pump is running? If there is a leak there that bleeds off that quick, there must be gas squirting all over the tank. I'll see if I can hear it.

Thanks

 

Trying to look at all the possibilities, yes leak could be small enough that fuel pump can build pressure and have pressure drop to 0 in just a few seconds once pump quits running. And yes also to your new pump having a bad checkvalve. Could be either or a fuel injector leaking.

 

Just as a point of reference, a couple of weeks ago I tested my 96 LT1 and it held 46 psi rock steady for over an hour at which time I terminated the test.

So yes, you have a leak somewhere, probably internal, unless you're finding puddles on the ground/floor. Based on what you've posted, I'd first suspect the pump.

You probably won't be able to hear a leak at the pump; it only has to be a tiny one to allow pressure to quickly drop. Putting clamps at all the pump connection points could well solve your problem. That's what I did on my 86 Vette's pump hoses.

Jake

 

I disconnected the fuel line at the regulator and did a pressure test in both directions. The leak is on the engine side.

 

What I don't get is, if there is an injector leaking, wouldn't you notice it in the way the engine runs?
:LS1LT1flag:

 

While we like to hate computer controled cars, they are really amazing in the amount of compensating they can do before they can no longer keep things in control and the car runs bad. Back in the old days when something wasn't right, you knew it. Now the computer can mask problems and when it can no longer hide the problem, your car runs badly, but the problem has been there for awhile and has now gotten bad enough that the computer can't correct for it.

 

That makes sense. Thanks. :LS1LT1flag:

 

There are two most common areas for what you're seeing. Either the Fuel Pressure Regulator is leaking internally, causing the pressure to drop immediately/quickly and/or a leaking injector(s).

A leaking FPR many times (but not always) will show up as gas in the vacuum hose. Even a strong smell of gas in that hose can indicate a FPR problem.

To check the injectors, I simply unbolt the fuel rails from the plenum/intake while leaving the fuel lines and injectors still attached and energize the fuel pump so that it runs continually. A leaking injector will show up.

Jake

 

There are two most common areas for what you're seeing. Either the Fuel Pressure Regulator is leaking internally, causing the pressure to drop immediately/quickly and/or a leaking injector(s).

A leaking FPR many times (but not always) will show up as gas in the vacuum hose. Even a strong smell of gas in that hose can indicate a FPR problem.

To check the injectors, I simply unbolt the fuel rails from the plenum/intake while leaving the fuel lines and injectors still attached and energize the fuel pump so that it runs continually. A leaking injector will show up.

Jake

Congradulations about your son! Semper Fi!

I changed out all 8 injectors over the weekend. Haven't done a pressure test yet, but it sure is running better already!

Thanks! :LS1LT1flag: