OK, I finally put a Walbro fuel pump on my truck. I built the kit myself for $210 icluding pump. I had to adapt the pump and fittings to the Vulcan big line kit. The kit took a little creative thinking but overall was pretty basic.

My question is: I was hoping for a little more fuel pressure. Idle, 15/16 psi and 10-12 psi WOT. I know that these are good numbers but if this is all that I am running than why did I need the check valve? The check valve opens at 17psi which I never reach. Should I have more psi than this from that Walbro?

By the way I love how quite this pump is. I happy with the purchase.

 

Leave it alone, it's working fine. Any more pressure and you might get hard starts. That's the same pressures I'm getting with my FASS HPFP

 

22-21 psi @ idle
20-19 psi @ normal driving
never pulled below 17 @ WOT

what diameter line are you using...3/8 or 1/2

NCA

 

The fuel lines are 1/2" and the pump is located by the fuel tank.

 

I have a home-made "big line kit" myself... everything is 3/8" with AN fittings. Stock fuel filter and Walbo 392 pump by the tank. Then 1/2" line from FF to VP... , no banjos. I also have 3/8" inch line from pickup to pump inlet.

I had Doug at Glacier Diesel set my pressure at around 16. And I sit idle around 15+ and normal cruise is 14.5-15. WOT maybe hits 14. Extremely steady.

I would expect your pressures to be better honestly.

CORed

 

just a shot here....i think it is volume....for example

i know when i pump (fire department) and say i am flowing (just for ease i will use made up numbers, the idea is the same) 100 gallons of water every 1 minute out of 2" hose my pressure at the nozzle is XXXXX...now if i make NO changes other than the size of (diameter of hose) say to 3" i will have a different pressure at the nozzle...

think about it...i know the system will work with larger diameter fuel line but the system is desigined to push through 3/8 not 1/2" maybe talk to Richard at GDP..(he is more than accomidating) and see about increasing the pressure...i believe it is as simple as springs and washers...

like i said...i have never droped below 17 and that was for a milla second then it stayed at 18 for the rest of the WOT run...

some say 22psi is to high and casues hard starts....never happened here i love the pressure.

helps me sleep at night

NCA

 

Thanks to all for your responses. I will just leave it alone. Its not like I am running out of fuel.

 

So what exactly do you have in your fuel system. I have the Vulcan big line kit. 3/8" line before lift pump and 1/2" after. Is this what you're running? If so, I'll be ordering a walbro pump. I thought you had to run the special regulator and return line to the tank or fuel filler hose.

Brad

 

I have the same kit. I used Vulcan's Carter pump mount to house the Walbro. I do have a check valve or as you call a regulator. But I do not need it. I never hit high enouph PSI. Really, it is a just a safety percausion. The return line was a piece of cake. I bought the fittings for the return line at ACE Hardware. Let me know if you need any more help.

 

What type of regulator do you have? And where do you have it in the system?

 

Good question, if it's not post pump in the return line it won't work as designed. I questioned the placement and called GDP but took GDP's advice and it's working flawlessly.

http://www.glacierdieselpower.com/im...rf-Install.pdf

Look at page 7

18) Choose a location in the line between the new pump and the filter housing to install
the “T” connection. Make sure that you have enough fuel line remaining to reach
from the chosen “T” location to the return manifold in the tank fill neck. Try to allow
at least 18” between the pump and the “T” fitting location. Cut the line and install
the “T” using the supplied straight PushLok fittings.
Note: PushLok fittings do not require hose clamps.
19) Install the 90° PushLok connector into one end of the remaining hose. This will be
the new return line. Attach the 90° fitting to the remaining open leg of the “T” with
the hose facing the rear of the vehicle.
20) Choose a location for installation of the bypass valve.
21) Cut the return line, install the bypass valve and secure. There is a “T” stamped on
the bypass valve body. The “T” marking must be towards the fill neck end of the
return line.
WARNING!!! Bypass valve must be installed in the correct direction or fuel
system damage will occur!

 

You are correct, NorCal. Pressure in a pipeline consists of 2 components; velocity head (The pressure used to actually move the liquid) and static head (The pressure a gauge will read). One can be traded for the other if the pipeline size is increased or decrease. If a pipeline flowing "x" gpm has its velocity decreased by increasing the pipeline size, the velocity head will decrease and the static head will increase. If you reduce the pipeline size, the static head (or gauge pressure) will decrease and the velocity of the fluid will increase (requiring more velocity head).
Unfortunately, in this case physics work backwards from what you would like to see in this situation. The larger 1/2" line will reduce the static pressure instead of increasing it. The difference in pressure between a 3/8 and 1/2" line at theses flow rates will be pretty insignificant though.
Cougsfan

 

The walbro is capable of something like 120psi. The reason you're only seeing 15-16psi at idle is because the checkvalve is releasing the fuel. If you add shims (washers) to the checkvalve, it will increase the spring tension and raise the pressure needed to open the checkvalve.

 

Argghhh! I can't even keep track of what I am saying. (maybe I am dyslexic?) The 1/2 pipeline would have more static pressure than the 3/8" line, as its velocity, and velocity head, is lower.
Cougsfan

 

What you are saying, Svanni, is the relief valve is releasing the pressure? Do the springs on relief valves typically wear out, and do people often change lift pumps when all they really need to do is shim the springs on the pressure relief valve?