Hello Would A Leak In The Water Seporator Cause A Drop In Fuel Pressure And Cause The Engine To Die And Not Run. Or Is There Any Other Ideas Besides
The LP That Would Cause Low Fuel Pressure At The Line Going Into The VP44. I Have Almost Know Fuel Pressure At My Supply Line Going In To My Injector Pump But My LP Is Brand New So Any Ideas.

 

Just because your LP is brand new doesnt mean it hasnt died already.

 

HA Ha true but i ran the voltage tests and the tests say it is still good. would the truck still start with out fuel pressure and would the vp44 cause low fuel pressure if something was wrong with it.

 

Have you checked for leaking fuel yet?

 

I can't see any but if the hole is small enough it might not leak

 

If the hole is small enough to not leak , common sense tells me it will be small enough to not cause a pressure drop either.

The LP can sound like it is working just fine , but already be toast. The voltage tests don't really help you with anything , you could have bumped the starter to see if it still ran.

I have a friend with an 01, and his pump sounds fine , but his FP is low.

 

You need to install a FP guage to know what the pressure is post fuel filter. Have you tried bumping your starter to see if the FP is pumping? The LP does not run full time until the engine has started. When you turn the key on it runs for a second or two to build pressure to the VP then shuts off. If you bump the starter it will run for 22 seconds then shut off cause the motor has not started.

 

Have you thought about disconnecting the fuel line after the filter, put a clear plastic hose on and get a container to catch the fuel. bump the starter to just roll the motor over, the lift pump should start to run for around 20 seconds, and you should have greater than 40ozs of fuel in container. Curious if you understand about bumping motor to run pump. On your last post you posted it only ran for 5 seconds. That means you only turned the battery on.

 

Here's a stupid question.... Have you changed your filter? If the filter is old it could very well be clogged. Especially with the new ULSF fuel. I hear it does a great job of cleaning out fuel tanks, lines and even the station tanks. It could very well clog the filter in a short period of time. A new lift pump can't provide fuel through a clog. Good luck.

 

Turn your keyswitch on-off-on-off-on then look at your odometer for codes.

 

Your signiture says you have a FASS but from your post it sounds like you have the stock lift pump. I have heard of some guys running 2 pumps in series, is this what you are doing or are you talking about the FASS? If you are running fuel through an old stock pump and it isn't turning it will create an obstruction and you won't get enough fuel to run the truck. Also some folks keep the stock filter and run the FASS fuel line to the stock filter housing so they can keep the heater and most times they have the gauge sensor there too. You still need to make sure that this filter is not clogged. If you have a new FASS and have bypassed the old system you should not be having fuel delivery problems. Make sure there are no kinks in the hose and that you are not drawing air into the system too.