Engine/Transmission (1998.5 - 2002) Low Pressure reading with FASS / Bleeding gauge

[SConklin]

I recently changed out my fuel system to the FASS, however, at the same time, I swapped out my fuel pressure gauge. I have been getting low fuel pressure reading on the new gauge. It is a Hewitt mechanical gauge, with an isolator and a coolant line running to the gauge in the cab. I also only ran the 3/8" FASS line to a Wildcat banjo bolt on the stock filter setup, instead of direct to the VP44 (I did not have enough line to bypass it, nor did I have a t-fitting or anything to run to the fuel pressure guage, plus, I like having another filter in the system. ) My fuel pressure is now reading 9psi at idle, and 7. 5psi at WOT. The small drop is great, however, overall, both pressures are too low, and definately less than I expected to see from the FASS - it is less than the stock lift pump, even as it was going out. I thought that I bled the fuel pressure gauge lines (both the fuel and coolant sides) correctly, however, now I am not sure. How do most of you bleed these lines? Especially the coolant? If it is not the gauge, why would the pressure be so low? Can you adjust the FASS at all? Any other ideas?

 

[tajensen]

You shouldn't have to worry about bleeding the line from the isolator to the gauge, that is usually a closed system. The way I bled my system was to tighten down all the bolts except for the one that connects my fuel line from the VP44 to the mechanical isolator. Then I bumped the starter (turn the key to the START position for a split second), and allow the pump to run. When fuel started to leak out of the fitting, I tightened it down. All the air was pushed out of the lines, and my pressure readings were good. This was with the Carter LP, and not the FASS, but I don't see how it could be much different. Good luck, and have plenty of rags handy.



-Tim

 

[GIT-R-DONE]

SConklin, call Brad @ http://www.dieselpp.com/ , he may be able to help you out. I too have to call him about low pressure, but there is a way to turn it up to where you want, I just haven't had the time to call him, yet. Mine is at 9 lb. all the time. I am not too worried about running at 9 because I know there is a ton of volume going through the system.

From what I read on your post, you are running it through the stock filter too... ..... I don't think that is necessary and may be part of the problem too. Trying to push it through your stock set up too may be the reason for the low pressure. Just my . 02 Don

 

[rbagley]

If memory serves me, I read that the FASS is factory set at 8 PSI. You can adjust it to higher pressures by doing something with the inlet or outlet line.



Best to call the factory and find out the correct way to adjust it.

 

[pgleavitt]

I had a fass installed on monday. I have 8 psi(7. 5@wot) and wanted to set pressure higher. Called Brad and very easy to fix. They also have a 20 psi spring you can replace. The place that did my install warned me that in hot weather the truck would be harder to start at 20psi. I now run 14 psi.

 

[rkressg]

I beleve, but I will have to look, there is a spring on the return side. You have to remove a plug and slightly streach the spring to increase the FP. You can also get a different pressure spring. The FASS system should be able to hold a constant pressure no matter how hard you push on the loud pedal and anything over about 17 psi will make for hard starting.



just my $0. 02

-Rich