Engine/Transmission (1998.5 - 2002) Poll: What Kind Of Lift Pump Do You Run

[dmagenau]

Pumps lines and whatnot. Greatest thread ever, too bad so many miss it.



i can't seem to find the "pumps lines and what not" thread. I finally got a FP gauge in this past week and showing weak psi, so i have been doing alot of reading on here the past few nights to try and decide what my next step will be. 1) Vulcan Big line kit 2) Maybe FASS system, but the more i read the more i dislike the later. My next is injectors after fuel system can feed them properly.



If you could help me find that thread it would be great.



Any thoughts on my situation???

 

[Fishin Guide]

I agree with Hohn. I did the cam change for the mechanical pump. Simple and reliable and clean.



Bob, I am no expert on the bypass on the VP44, but after trying to regulate my pressure from the 12V pump, I removed the overflow alltogether and still could not get less than 30 psi.



The VP is a tighter pump than the older 12V pumps. So, they don't have as many paths for the fuel to flow around to drop the pressure off. I came up with a solution to fix the fuel pressure issue, but I have no ill effects yet of running higher pressures.



As far as the best electric pump, that is debateable. I would love to see the be all- end all electric that would hold up. But, that seems like it's a ways off. I am just hoping that my lift pump solution is better than the others and justifies the other benefits of the cam.



Dave

 

[R-N-R]

pumps, lines & whatnot

 

[Texas Diesel]

Texas Diesel - Any extra pressure applied to the VP simply opens the VP bypass valve. EXCESS PRESSURE DOES NOT COOL THE VP, it only opens the bypass valve.



Where IS the bypass valve located? How does it mix with the fuel that DOES go through the Vp44 for cooling? Does the bypass valve bypass the incoming excess pressure directly to the VP44 fuel return?



Bob Weis

Bob,



The bypass valve is on the outlet banjo on the VP, just forward of the inlet banjo. You can take the banjo off and see the valve in the bolt. I had to replace one because it was causing very low fuel pressure by sticking open.



The fuel incoming fuel is let inside the VP by the inlet banjo. This fuel is fed directly to the primary (engine driven) vane pump. Then the fuel (at unknown but variable pressure) is fed to the HP pump. The incoming fuel is sort of "Y" between the LP vane pump and the bypass valve. Any extra (>15PSI) pressure is simply diverted around (or bypasses) the VP.



The one thing I suspect but cant verify, either way, is if a small (unused) amount of output from the HP pump is added to the return.



The only "fuel cooling" of the VP occurs by feeding the VP with COOL fuel, not volume. As you have embarked on doing to the benefit of us all.



Surely some one can add to this.

 

[GWedekind]

IMO, Texas Diesel is hitting it on the head. Zero PSI at WOT doesnt prove that volume isnt there. Kinda like the water hose at your house... . 40-60 psi dead headded with a gauge but when you open the spicket and let it flow you get zero psi with plenty of usable flow. I said it before that Im old school and thought that pressure was GOOD and no pressure was BAD but we dont have the type of fuel injection system that relies on rail pressure like an EFI car would.



I hooked my Holley blue back up to supplement the low psi intank pump and with a little tweeking of the spring Im getting 20psi at idle and 10 psi at WOT. Im trying to get it back to somewhere around 14psi but have to get a new spring to start over on my tweeking. With the truck running perfect on this set up I switched over to my aux tank that has 75% veggie 25% diesel and pressure goes from 10psi at idle to zero psi at WOT and there is no noticeable difference in power at zero psi on veggie compared to 10 psi on diesel. No buckung, spitting or anything. So if zero psi was representing a lack of fuel why does it run just as good?



I also noticed that at zero psi and within a split second of lifting off the go pedal, fuel pressure blips back up immediately. Im convinced that zero psi at WOT may not be all that bad with a mild or stock truck.



I believe that we need a certain amount of pressure present as a way to monitor supply since we dont have flowmeters to see what is going in the VP and out of the return.

 

[JTBMC]

I got tired of changing lift pumps every couple of months, and spending a small fortune for them so I went to the FASS with #6 AN fittings and stainless braided lines. No more LP troubles in two years.

TJ

 

[GWedekind]

Just to clarify my opinion on zero psi... . if you have a LP faiure like we have seen with the carter pumps, zero psi would be a VP killer. But if a replacement LP like the Holley, fass, airdog or ?? flows the necessary volume but has low psi at WOT on stock or mild trucks it should not hurt the VP.



All of my VP failures happened with plenty of fuel pressure. All of them were heat related. Heated Veggie is what killed 4 pumps in the last 20K miles or so. I no longer heat veggie!!

 

[Devan Manis]

So, the ideal gauge would be some kind of flow meter? Since we don't have one, would a gauge that showed vacuum as well as pressure be a good canditdate?

 

[ToolManTimTaylor]

Was a PE 4200 with -8An lines. Then it bit it and the F. A. S. S went on and I am real happy so far 20 somethin thou later.

 

[GWedekind]

I dont have an answer for that one. Devan, did you read that post "pumps lines and wantnot" ?



eye opener for me

 

[GWedekind]

I havent seen a fass up close. what kind of motor and pump unit is on it. Is it a gerotor or a vane style?

 

[Texas Diesel]

So, the ideal gauge would be some kind of flow meter? Since we don't have one, would a gauge that showed vacuum as well as pressure be a good canditdate?

YES YES YES! You get the idea.

 

[J.R. Adkins]

I voted for the Aeromotive.



Very flexable and reliable. Not cheap tho.





J. R.

 

[Texas Diesel]

So, the ideal gauge would be some kind of flow meter? Since we don't have one, would a gauge that showed vacuum as well as pressure be a good canditdate?

I had to come back to this.



I wondered if anyone would pick up on this idea too. You definately get the cookie.





If you find a +16PSI to say -14. 7PSI ( one atmosphere ) PLEASE post the source. This is what I want in my cab.

A gauge that read all the way to -14. 7 would be over kill.

 

[Devan Manis]

this probably won't work, but...

I had to come back to this.



I wondered if anyone would pick up on this idea too. You definately get the cookie.





If you find a +16PSI to say -14. 7PSI ( one atmosphere ) PLEASE post the source. This is what I want in my cab.

A gauge that read all the way to -14. 7 would be over kill.

This probably won't work, but what about one of those boost gauges for a gasser that also show vacuum?