I’m sure this has been best to death and a can of worms I probably don’t want to open. Looking for the most reliable lift pump. I’ve been repeatedly told lately to stay away from fass and air dog as they’ve supposedly went down hill. Currently have an air dog 100 that I’m not satisfied with. Thinking with my mods I should jump to a 150 or 165gph. Open to suggestions but would like to stay with the dual filter type. I’m a brand new member so forgive me for not understanding the searches and topics yet. 

5 hours ago, Wyocowboy1990 said:

Currently have an air dog 100 that I’m not satisfied with.

 

What is it that you are not satisfied with?

 

What are your mods?

 

- John

1999 3500 quad cab 4x4 5 speed. 5 inch Mbrp 4 inch down pipe. 5x10x18 powderwerx717 custom tip. BHAF. 150 injectors, fleece cheetah 63 mm drop in. Ats 3 piece pulse manifold. Banks monster ram intake. Quadzilla adrenaline iquad with stock tunes at the moment. Air dog 100. Valair dual disk organic quiet clutch. bilstein 5100 series shocks. 2 inch spacer level. 235/8017 on rockstars.. Work in progress.  Idk if my ball and spring are just bad possibly. But I’m dropping to 6-7psi at anything more than idle. 

I’m not a mechanic by any means. But I’m mechanically inclined and can turn a wrench. 

22 minutes ago, Wyocowboy1990 said:

But I’m dropping to 6-7psi at anything more than idle. 

 

That sounds about normal for a 100 gph lift pump.  What is your lift pump pressure at wide open throttle driving with engine under full boost at around 2200 rpm?

 

Is your lift pump mounted in the OEM position on the engine block?  Or, is it frame mounted (a better option)?

 

This site owner uses a frame mounted Air Dog lift pump.   He will probably post the specific information about his pump in a little while.

 

- John

 

 

 

 

It’s frame mounted. And I honestly don’t remember. I’ll go for a drive and check 

Wot I’m dropping to about 5psi and the needle bounces like absolute crazy between 5 and 12 psi. 

I’ve considered jumping up to a 150 or 165gph. But wasn’t sure if there would be any benefit over the 100gph

25 minutes ago, Wyocowboy1990 said:

Wot I’m dropping to about 5psi and the needle bounces like absolute crazy between 5 and 12 psi. 

 

The fuel pressure gauge should always be steady, regardless of the pressure reading.  That needs to be corrected. 

 

A reading of 5 psi at WOT is fine for the needs of the VP44 injection pump.  Moving to a 150 gph pump will raise the fuel pressure somewhat, but it does not change the volume of fuel returning to the fuel tank from the VP44.  The VP44 has its own fixed displacement vane pump inside that controls fuel flow and pressure for the VP44's internal components, and for the fuel volume returning to the fuel tank.

 

- John

Good to know. Thank you!

The bouncing needle could be caused by a lift pump ball check valve vibrating or by a faulty gauge sending unit depending on your gauge setup. 

 

- John

 

1 hour ago, Tractorman said:

The bouncing needle could be caused by a lift pump ball check valve vibrating or by a faulty gauge sending unit depending on your gauge setup. 

 

Both are correct. If a bad pressure regulator check ball or valve it's possible to bounce of the needle. Another one that the lift pump could do is if it does not have air separation like AirDog or FASS it's possible to see air bubbles being passed along by the pump like the stock lift pump or Raptor or DDRP series pumps that don't have air separation systems. This could stem from poor suction lines back to the tank and it will continue to draw air into the inlet of the pump and continue to bounce because of air being pulled in. I've seen stock fuel baskets the plastic tube does crack open and suck air in while the fuel level is lower than the crack in the tube in the sender. 

 

The bad sensor could do it as well. Being mine when it finally failed last month it was a bouncy needle and then started to rise till it was pegged out showing 30 PSI. I've got many years of service out of that one electronic sensor for fuel pressure on my ISSPro EV2 series.

Thanks so much moparman1973. I’ll definitely do some digging now that I know where to start. I love this site. I’ve learned so much even before joining. And I’m gonna get isspro. Previous owner put in cheap Glowshift on a poorly installed pillar gauge. 

To check for a cracked pickup tube in the fuel basket fill the fuel tank; the bouncing needle will go away because the crack is covered with fuel.  

Will do. Thank you. I think it’s a faulty sensor. 

1 hour ago, Wyocowboy1990 said:

Will do. Thank you. I think it’s a faulty sensor. 

Sensor is replaceable there is a article in the fuel section with the part number. I know that @dieselautopower has a full module replacement too.

Yessir I was just looking at their website. 

There is also Mopar1973Mans washer mod that bumps pressure up to compensate for a weak spring. 

Got it fixed. Thanks everyone for the replies and feedback. Ended up being a weak spring and a missing fuel cap. Good as new now.