I could use some help! I installed a fass fuel pump the other day and my truck ran fine. Now 3 days later it does not start as fast as it did. could it be that I need to change the fuel filters again ?

 

is your fuel pressure high when you try to start it? if so that could be it, if you are less then 2lbs at cranking you ougt to look for a leak that could be giving you a bit of air.

 

Ditto - either sucking air or too much pressure while cranking (VP44 likes to have the LP pulsed while starting to keep the fuel transfer pressure low)

 

It only has 18 psi of fuel pressure! Alot more than it used to run with the original lift pump. I looked for leaks, did not find any.

 

Is there anything that can be done to lower the fuel pressure if it is too high?

 

I'm sure Diesel-Dan will weigh in soon on this one.

 

I just checked my fuel pressure guage when I started the engine. It goes to 17 psi then back to 0 until the engine is cranked over. then the fuel pressure goes back up to 17 - 18 psi.

 

Perusing the service manual, I found this:
Lift pump operates in two distinct cycles, engine running and engine cranking. During cranking the pump operates at 25% duty cycle to limit the pressure delivered to IP. During running, it operates at 100%.
During cranking, the LP should provide 5-7 psi of pressure. To test, bump the starter but don't start the engine; the pump will run for 25 s during which the pressure should be 5-7 psi.
During running, the LP should develop no less than 10 psi of pressure at idle speed.
The IP overflow valve opens at 14 psi to let excess fuel drain back to the tank (this is why I am a bit curious to see how people report 26+ psi with Walbros; I guess the flow rate is so high that the bypass valve on the VP can not keep up and extra pressure builds up).
Probably stating the facts that everybody knows, but just in case.
-P

 

so your fp is low as you are cranking, this would tell me you need to double check your work and tighten everthing again, it takes the tiniest little bit of air on the suction side to cause hard starts.

 

I'm back ! Thanks for the input. i will double check the fittings and just for giggles replace the prefilter to the Fass fuel pump. I had a tech tell me that I really didn't need the prefilter before the pump but I figured it may help to prolong the life of the pump.

 

When exactly, and for how long, are you getting zero fuel pressure?

 

I thought I would get back to you all. I got under my truck today and replaced the hose clamps that came with the Fass fuel pump kit. The clamps are too big for the line and was allowing it to suck air. Great call guys!!! Everything works as it is supposed to now. thanks for all the help. Maybe I'll be able to return the favor some day.