So i replace my old style 3/8 fass system with a new airdog II-4g model due to no lift pump pressure and couldn't get system to prime and get rid of the air. Now even with the new system in, I go a few blocks down the road and my low fuel pressure light turns on and starts stumbling when going to a stop and sounds awful. What the ;lkjasdf;ljasd;lfkja is going on here? Im getting fed up...ive been so frustrated trying to figure this out the past couple months. I love cummins but this one is beating me up. And don't want to risk trying to drive it to a cummins shop. This is the greatest site ever btw.

Actually it doesn't trickle out at all it flow quite well.

 

As for failure from heat not as common as you would like to think. Ask yourself or do a search for P0168 codes. Tell me how many times you've seen a P0168 code reported on any forum or web site? Most VP44 failure stem from AC noise issues not heat related as most people tend to believe. If so please explain how I've got 12 year old VP44 that survives 110-115*F summers and then put into the freezer at -20 to -25*F every winter? I've got 215k miles and clocking on my VP44 still pulling strong.

 

10 minutes ago, Cumminz said:

Might as well go with the p-pump then.

 

You be losing functions possibly. Like with my truck being its fly by wire cruise I would lose cruise control for sure. P-pump conversion I don't suggest for daily drivers some people get away with other fight it constantly. More or less like ripping off a perfectly working electronic fuel injection on car to drop on a carburetor. Not that it won't work but it does create its own issues just like P7100 conversion on our truck.

 

 

Edited July 10, 20168 yr by Mopar1973Man

I actually just saw that video from you before you even posted it lol. But this proves that I DO have an issue with the return from vp44 as shown in my video, the clear plastic hose is return from vp44 and there is nothing coming out when bumping the starter. You did the exact same thing i did in your video. So my new vp44 is have a return flow issue if nothing is coming out when bumping the starter then right? Like the overflow valve is bad on this New pump?

What matters is the return flow while its running. All the rest of the video was for to prove the lift pump can indeed push fuel past the overflow valve for priming purpose and the tiny hole can and will flow fuel for priming purpose. So for cooling purposes it only takes about 30 seconds after starting the truck to drop the pump case temperature back to fuel tank temperatures. So again the flow rate while running is the important one not bumping the starter meaningless really.

This is why the upgrade form the stock value of 10 PSI to 14 PSI was now used. Because it insures that the overflow valve will be open no matter what providing the best flow through the pump and cooling the pump does rapidly from "heat soak" state.

So since Air Dog went to their own return flow from the pump and I want to stay with an electric pump, is Fass the best option at this time for elect lift pumps?

It really depends on who you ask but I'd say right now that generally FASS is considered the more reliable pump. Although Airdog does seem to have worked through most of the issues that plagued them 3-5 years back. FWIW I went FASS and don't regret it!

As for FASS they are well built pump. The problem is the pure size of the pump and protecting the pump and filters from the damage path of flying road debris flung up by the front tires. The mounting kit uses the bed mount on the driver side of the vehicle. Some say they can get it up high enough that the filters are not seen hanging. The problem still remains that the filters get struck from objects flung by the front tires be it gravel, rocks, chunk of lumber that fell off a truck. AirDog on the other hand had its own list of short coming and failures. The AirDog pumps are much smaller and very easy to hide. The current AirDog mounting kit includes plastic for mounting plates which is a shame because we know plastic won't hold up for long. I've installed both AirDog's and FASS systems both.