GFS 392 Questions

[Tinman]

I finally got around to getting my GFS pump installed a few months ago. I have noticed a few unusual things that I wasn't sure was normal.



-When the truck is cranked cold (even on a warm day) the fuel pressure starts out at about 16-17 psi. After a warm up of 15-30 minutes the pressure rises to the usual 19 psi. If started warm it goes to 19psi. Is this normal and why is it happening?



-I have had the tank down to about 1/8 of a tank twice with DTE of about 100 miles on the overhead. 1st time was at install and I added 5 gallons before I drove to town so there was about 6-7 gallon in it. Both times it started getting air in the line on braking and accelerating dropping pressure to about 10 psi off and on. Truck ran fine and pressure never got

 

[Jeff Knight]

Mine hasn't risen in pressure. I need to get my gauge fixed though. I think the air is from having the fuel low in your tank. The pump moves so much fuel it sucking air. Mine did that to me when I installed mine. I went to the station to get fuel that I had to pull out on a slight hill to get to the station. Went to start the truck after fil-up and had to cycle the pump a couple of times to get it to fire. I don't go below a quarter tank and it hasn't done it since. Plus it cost to much. Hope this helps. Jeff

 

[Scrappy]

I finally got around to getting my GFS pump installed a few months ago. I have noticed a few unusual things that I wasn't sure was normal.



-When the truck is cranked cold (even on a warm day) the fuel pressure starts out at about 16-17 psi. After a warm up of 15-30 minutes the pressure rises to the usual 19 psi. If started warm it goes to 19psi. Is this normal and why is it happening?

Mine did this too, I don't know why but I think it might be an issue w/ the FP gauge (at least that is what I think is up with mine)

 

[Tinman]

My pressure variation is very consistent. The gauge has been working fine, well before the install of the Walbro. I thought it may have something to do with fuel temp/viscosity. As far as the air in the line, I wanted to make sure I didn't cut the pick up tube too short. Mine looked like the install pictures right smack in the middle of the tank with a slight curve. I noticed the stock pump had a well molder into the tank to keep a little fuel in the pump pick up while fuel is sloshing around at low levels. Of course, the Walbro does have this so I'm sure that's the issue. I just wanted to make sure I didn't install the pick up tube wrong. I rarely run the tank to <1/4 but you never know when you might have to push it to find fuel in the boonies.

 

[Jeff Knight]

I put the factory fuel module back in my truck after taking the in-tank pump out. It still pulled air into my system. Jeff

 

[ENafziger]

Tinman, mine does the exact thing you are describing. I have the DiPricol Optix gauges, and I often seen 17 psi at startup, with it settling out at about 19 - 20 when warmed up fully.



Also, at about 1/8 tank, my pressure begins dropping, and the truck is hard to start. If I swap the electrical connectors and run off of the factory pick-up/pump assembly, there are no issues... other than only running 7. 5 psi fuel pressure.



I did the fuel tank vent mod at the same time as the GDP install, but didn't really gain any fuel capacity because I can't run below 1/8 tank! It did allow the usable capacity to remain close the same as stock I guess... --Eric

 

[Tinman]

I did the vent at the same time also and was excited about the increased capacity. But, like you said, it really only keeps the range at roughly stock. Oh well. A least might is acting like everybody elses.