Engine/Transmission (1998.5 - 2002) Fuel Pressure at WOT?

[snowracer69]

Just got done putting my Autometer Z-series 0-35 PSI boost gauge in as a mechanical fuel pressure gauge. It looks really slick (I think) and seems to be working 100%. Anyway, here's my pressures:



Idle: 14-15

Cruise 11-12

WOT w/ Comp on 3x3: 8-9

WOT w/ Comp on 5x5: under 5 PSI



Now, I have a brand spanking new lift pump on there (just replaced a week ago), and the majority of those numbers don't bother me, EXCEPT the one when I have the Comp on the way up, and it sucks it down to under 5 PSI, and I let off before it bottomed.



Am I looking at a pusher set-up before I put my DDII's in? (which will be in a couple months). Should I be concerned with these numbers?



BTW, readings are post filter, and only have one of Geno's Banjo bolts on.



Thanks for any insite, Josh.

 

[Bob Wagner]

I wouldn't be too worried unless your going to have your foot planted on the floorboard all the time



Just dont go down to zero

 

[JerryWallace]

35# guage?

 

[snowracer69]

.

NXS,



Yes, 35 PSI boost gauge is what I'm using. It works good, and will be able to handle the higher pressures when I add a pusher pump someday, which I figure I'll have to when I start adding more power.



You don't like the idea of a 35 PSI gauge?



Josh

 

[JerryWallace]

Nothing wrong with a 35, I thought you may be pegging the needle with the turbo mod you have.

jerry

 

[snowracer69]

.

NXS,



The 35 PSI gauge that I just installed was for fuel pressure only... it is in my cubby hole. I have a 0-60 PSI boost gauge on my triple pillar that I use for the actual boost. Even with the wastegate turnbuckled, I can only see about 34 PSI at WOT with my Comp on 5X5, pulling a good long hill... but also at the same time I see 1500* F on the Pyro.



I'll be posting a bunch of pics of my gauges and stuff in another thread here shortly in the 2nd gen no engine/drivetrain forum.



Josh.

 

[FourBarR]

egt

snowracer 69 if your seeing 1500F you better be prepared for melted aluminum. think cummins says 1250F or 1300F. :{ :{ Oo. Oo.

 

[KLockliear]

Snowracer69, you should see if you can change your FP pickup to the banjo ON the VP44 if you have not changed that line. The banjo fitting in the end of the line at the VP44, not the bolt itself, is the biggest restriction in the system. If you have that stock line, and are measuring FP before that spot, you are likely seeing an falsely high pressure reading.

 

[jerrethomas]

u prolly shouldn't run over the factory fuel pressure cause it could cause hard starting. just watched the vp44 section on the cummins virtual college that our school has.

 

[KatDiesel]

Originally posted by jerrethomas

u prolly shouldn't run over the factory fuel pressure cause it could cause hard starting. just watched the vp44 section on the cummins virtual college that our school has.

The ECM cycles the lift pump on start up to prevent high fuel pressure on start up. Under 10psi startup is fine, thats why if you add a pusher you tap into the stock harness and the ECM will cycle the lift pumps. They used to run for a while when you turn on the key, however if you have a newer truck or got a reflash you'll notice the "buzz" of the lift pump on start up got quite brief.

 

[snowracer69]

hmmm....

So what's the deal here? I asked the questions before, and everyone says that post filter is as good as anywhere, and I know for a fact that lots of guys on here are running 22+ PSI with their Carter pumps, so what am I doing wrong? I don't think I'm taking a chance on anything, and I feel like I'm getting pressures from a good place... yeah, not right at the VP-44, but pretty close, and good enough to know if my LP is still working or not. Should I replace all my banjo's? I know I should, but is there that much to gain?



Josh.

 

[Bob Wagner]

yes, all the banjos need to be replaced to remove all the restriction points

 

[KLockliear]

Think of it like this. Take a garden hose and hook it to the faucet. Now put a spray nozzle on the end. Put a gauge in the middle. Turn it on and you see some pressure. Open the nozzle at the end. The pressure you see in the line is not the same as what is coming out of the end unless it's wide open (and it's not with the stock line).

 

[jerrethomas]

Originally posted by KatDiesel

The ECM cycles the lift pump on start up to prevent high fuel pressure on start up. Under 10psi startup is fine, thats why if you add a pusher you tap into the stock harness and the ECM will cycle the lift pumps. They used to run for a while when you turn on the key, however if you have a newer truck or got a reflash you'll notice the "buzz" of the lift pump on start up got quite brief.

ok got ya, just thought i would through that out there since i just watched it.

 

[rweis]

OK, so when you put in the NPT banjo's for the FP gauge, one goes into the last banjo ie on the VP44, the other (for pre filter) goes?, on the LP?, filter at pre filter?

 

[Huff N Puff]

The stock fuel filter is very restrictive over 350hp

Dont know where your horse power is,but when I went over 400hp I noticed that I could suck my fuel pressure down to 0 at WOT and that was running 2 pumps. A racor 690 filter with a 10 micron element took care of that problem. It never drops below 10psi now. Merv

 

[Opz01]

Josh,



Your post has made for some good reading. I noticed that you are running a Comp with stock injectors, according to your sig. The only reason I mention this is that its seems kinda mean to the injector pump.

When I was running in that config my truck didn't go below 8 pds of pressure WOT. That was two years ago. If you are going to stay on this bombing capaign you might as well start with the fuel sytem. I ran AN6 from the tank to a $32. 00 prefilter from summit.

http://www.perma-cool.com/Catalog/Cat_page26.html

Then AN6 to a Carter 4600 to a Carter 4601 (Both on the rail. ) then to my fuel filter on the engine. I do like the banjo fittings from genos but I didn't use them. I added four 1. 25" holes on each of my stock banjo fittings. (Center the holes between the exsisting ones. )

***Be sure to debur both sides of the holes. ***

I run a sender on both sides of the fuel filter and put a three way switch on the side of the fuel pressure guage mount. So one guage can be used for pre and post fuel filter pressure. As I was told if there is more than two pounds difference btwn the two its time to change the filter.

I run 22 pounds of pressure and only on one trip did I have problems starting. And this was solved by stepping on the excellerator pedal a little.

I never have been a fan of running the egts at 1500 even for short qtr mile runs. Some of the guys that did this didn't melt their engines but did blue the pistons.

Gotta go good luck...



Opie