Engine/Transmission (1998.5 - 2002) FASS, Possible problem ???

[RSimmons]

Last year I purchased and installed the FASS 150/95. At that time, I had trouble getting the unit to prime but it finally did. The system generally holds about 20 PSI but pressure will fall off to about 14 PSI when accelerating with moderate to full throttle.



I remember reading one of Diesel Dans posts that stated there is someone running very high horsepower with the 95 and sees no drop in pressure. So, I am somewhat concerned as I am running a stock SO engine with no extra power other than a Edge EZ.



Originally, I installed as instructed in the FASS manual with the fuel line direct to the VP44. I had my gauge sender on the FASS pump gauge port. I have recently put the stock filter back into service with the 7 micron element feeling that a additional filter/ moisture trap/ heater can't hurt. I have the larger bango bolts from Geno's and have moved my fuel pressure sender to the VP44 inlet. The pressure situation did not change at all with my changes.



I have replaced the FASS filter and cleaned the moisture trap thinking there could be a problem there. I actually had to fill the water trap and filter before installing to get the system to prime.



I have inspected the return valve and spring (no problem)

The pump is very quiet (can barely hear it run) even when the system is not primed. This leads me to believe there is not a problem with the pickup module as I have heard pumps cavitate due to restricted inlet.



I have had the drain valve on the stock housing stick open and the pump seems to flow a strong stream of fuel (read made a big mess).



Any ideas or suggestions would be appreciated

 

[RSimmons]

Anyone else had this problem ???

 

[Cummins724]

I always cycle my key to bleed the system [bump the starter] & when pump stops... bump it again. [3-4 times] then she fires right up. As far as pressure... . that 14psi is more than enough. I have the same pump & fass 150's have more flow than 95's, but less pressure. These trucks need flow ... . not pressure.

 

[RSimmons]

I can bump the key and the pump runs for about 25 seconds. I repeated it roughly a dozen times and still no prime. So, I removed the filter and water seperator and filled with fresh fuel and the system primed on the next try. I am just afraid the pressure may become a issue if I ever add any fueling mods. I guess as time and finances allow, I'll find out