Engine/Transmission (1998.5 - 2002) Fuel Pressure after LP relocation

[Johnny5]

I just relocated my pump to the frame rail with a Big Line Kit and have notice a slight difference in fuel pressures when I start the truck and I need to know if this is OK or not.



BEFORE. . During the 2 sec pump on during the wait to start light I used to get a little fuel pressure say a couple pound and when I started the truck ther was immedate pressure



NOW with the KIT... There is no pressure during the 2 sec pump on time and when I start the vehicle initally I have zero pressure until a couple seconds then the pressure builds to normal.



Question is this "building up" of the pressure normal to the Big Line kit and it due to the volume needed to fill the lines? Not to mention will this couple of seconds get longer during the winter when the fuel get thicker?



It is really weird having to see zero pressure for a few seconds when before the kit I did not see this happen. Also I'm wondering if it could cause problems in the winter due to the thicker fuel which could result in a longer time to build pressure to normal



Thanx,

Johnny

 

[DSeamans]

What are you considering "normal"? It probably is the big line kit if you are running the stock pump. You can bump the starter and the pump will run longer building up the pressure before you start.

 

[BDaugherty]

Did you change anything about how you were monitoring fuel pressure during the install? Also, do you have any leaks where the pump and lines could be losing prime? With much more volume between the pump and gauge sending unit, it may be "normal" for your setup. I'm running a similar setup, except that I have a Walbro pump. When I turn the key to on, my pump runs for less than 1 sec. Fuel press will usually be around 8 psi when I'm turning the key to "start" and then immediately jumps to my normal 18 psi.

 

[Johnny5]

The only thing I did with differently with the kit is that I did not install the line from the FF to the VP yet, basically since I needed the tapped fitting for pre FF pressure (also have post-FF gauge) and my existing gauge setup bolted on directly since it was the same fitting that was supplied with the tapped fitting.



I would suppose that I'm not losing prime since the pressure builds up and it has not created a hard to start or rough idle syptom that would show not having fuel at all cylinders. Also I check for leaks and did not find anything, at least no diesel was seeping out, would a leak be small enough that air could get in but not let diesel out??



My old setup had the FP gauge just inches from the LP, now with the LP a bit further away with a larger pipe that is lower than the FF (& FP gauge) could it be the fuel is draining back down the section that goes up from the framerail to the FF?



Thanx...



PS. . What I meant by normal is the extra few seconds to "build pressure to approx 13psi" something to be expected as with the stock setup I did not see this length of time

 

[RJWEST]

Air in the fuel press sense line ?. Bleed at the gage Or isolater

Mine did the same thing,

 

[Johnny5]

Air in the fuel press sense line ?. Bleed at the gage Or isolater



Mine did the same thing,

I was thinking about this when it first happened but wrote if off since my other FP Gauge line was not taken off. But know that I am thinking about it I bleed the air from the schrader valve and air could have gotten in the 2nd FP line.



This past w/e I did a lot of driving with the new setup and things have seemed to correct themselves where I now see some pressure at the 2-sec pump start and when the engine is turned on. So I am thinking the air must have worked itself out.



Thanx guys!!!

 

[RJWEST]

It does that..... Let it sit for a while and low pressure will come back,